THE CRANIUM OF THE NEWBORN INFANT AN ATLAS OF TOMOGRAPHY AND ANATOMICAL SECTIONS Robert H. Pierce MD. Michael W. Mainen MD. James F. Bosma, M.D. [Hus/rated by; Keiko Hiratsuka Moore Howard C. Bartner George P. M arsdcn US. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE Public Health Service National Institutes of Health National Institute of Dental Research Diagnostic Radiology Department, Clinical Center Bethesda, Maryland 1977 PUBHC HEALTH DHEW Publication No. (NIH) 76-788 For sale by the Superintendent of Documents. U.S. Government Printing Office Washington, Dc. 20402— Stock Number 017—047—00012—4 Preface This project. sponsored by the National Institute of Dental Research, was generated by the association within the Clinical Center, National Institutes of Health. of Robert H. Pierce, a Clinical Associate in the Diagnostic Radiology Department, of Michael W. Maincn, a Clinical Associate in the National Institute of Dental Research. and James F. Bosma, of the NIDR Section on Oral and Pharyngeal Development. To this association, Robert Pierce brought an interest in tomography acquired as a protege of Galdino E. Valvassori, of the Department of Radiology, University of Illinois Eye and Ear Infirmary. In some respects, this study is a sequel and analogue of The Interpretation of Tomograms of the Head, An Atlas by M. L. Daves and E. Loechel (1962), which was also produced intramurally at the National Insti- tutes of Health. iii _ w \w Hw‘n‘l‘wl‘lw . . II.LHEHIIHFIIFFII.L[£ Acknowledgments Appreciation is expressed to the various individuals and organiza- tions whose assistance has made this project possible. The specimens of infant crania were selected from the collection in the University of Maryland Department of Anatomy, by the arrangement of Frank Figge, and from the collection of the National Biological Laboratory, by arrangement of George Halpin. The figures and text have been reviewed at considerable effort by Galdino E. Valvassori. of the Department of Radiology. University of Illinois (Chicago) College of Medicine. by Frederick N. Silverman. of the Division of Radiology. Children's Hospital Medical Center. Cincinnati. by Edmund S. Crelin and E. Leon Kier. of the Human Growth and Development Study Unit and the Division of Neuroradi- ology. Department of Diagnostic Radiology. respectively. Yale Uni- versity School of Medicine. Preface Chapter Chapter Chapter Chapter Chapter Chapter Selected Bibliography ,_ 5 6 Table of Contents Introduction Anatomical and radiographic procedures General drawings and radiographs of the cranium Coronal tomograms and drawn sections Transverse tomograms and drawn sections , Sagittal tomograms and drawn sections Anatomical index . W, . We , q M 105 P53 PUBL Page iii 13 71 105 , 143 145 vii Chapter 2 Figure 2.1 Figure 2.2 Chapter 3 Figure 3.1 Figure 3.2 Figure 3.3 Figure 3.4 Chapter 4 Figure 4.1 Figure 4.2 Figure 4.3 Figure 4.4 Figure 4.5 Figure 4.6 Figure 4.7 Figure 4.8 Figure 4.9 Figure 4.10 Figure 4.11 Figure 4.12 Figure 4.13 Figure 4.14 Figure 4.15 Figure 4.16 Figure 4.17. List of Illustrations Page Drawing of cranium section embedded in stone ,, 4 Schematics of cranium with directional orientations A. Frontal view _. .. , ,, H, , fl 6 B. Lateral view , W , , . , 6 Drawing, frontal view , ,,, W, _ 8 Drawing. lateral view , _ . a. ,, as- , 9 Drawing. superior view, roof of calvarium removed 10 Drawing, inferior view , W , 11 Photograph of cranium, lateral view . fl ,, ., 14 Photograph of cranium, frontal View ”a . . 15 Photograph of cranium, inferior view a, . , . 14 Photograph of cranium, superior view, roof of calvarium removed , , ,._ M 15 Orientation of sections —on superior aspect of cranium, roof of calvarium removed H . , , 16 —on inferior aspect of cranium ., . 17 Tomogram , W . .. . , , a . 18 Drawing of anatomical section , , "a- . 19 Tomogram , , , a , 20 Drawing _ ,, , , _ _ a We. “We 21 Tomogram . am an, -,,,,,,___,, 22 Drawing W , a , W . . ,_ , 23 Tomogram , ._ , "N W, , W", .. 24 Drawing , _ _ "a. _. _- , . 25 Tomogram as ,, ,,,,,,,,,,,,,,,,,,,,,,,,,, 26 Drawing , _ , ,,, _ . ,,,,,,,,,,,,,, 27 Tomogram ,, , W ,, ,..,,.,,_..._.~_ . . ”-28, 29 A. Tomogram ., _ "flaw", _ W a“ 30 B. Drawing . w, ,,, _ _ W,“ ”Mr 31 ix Figure 4.18 Figure 4.19 Figure 4.20 Figure 4.21 Figure 4.22 Figure 4.23 Figure 4.24 Figure 4.25 Figure 4.26 Figure 4.27 Figure 4.28 Figure 4.29 Figure 4.30 Figure 4.31 Figure 4.32 Figure 4.33 Figure 4.34 Figure 4.35 Figure 4.36 Figure 4.37 Figure 4.38 Figure 4.39 Figure 4.40 Figure 4.41 Figure 4.42 Figure 4.43 Figure 4.44 Figure 4.45 Figure 4.46 Figure 4.47 Figure 4.48 Figure 4.49 Figure 4.50 Figure 4.51 Chapter 5 Figure 5.1 Figure 5.2 Figure 5.3 Figure 5.4 Figure 5.5 Figure 5.6 Figure 5.7 C. Tomogram ___________________________ 32 D. Drawing _____________________________ 33 Tomogram _______________________________ 34 Drawing __________________________________ 35 Tomogram ______________________________ 36 Drawing ________________________________ 37 Tomogram _________________________________ 38 Drawing _________________________________ 39 Tomogram ________________________________ 40 Drawing . _________________________________ 41 Tomogram _______________________________ 42 Drawing __________________________________ 43 Tomogram ________________________________ 44 Drawing _________________________________ 45 Tomogram aw- __________________________ 46 Drawing ____________________________________ 47 Tomogram ______________________________ 48 Drawing ________________________________ 49 Tomogram ___________ . ____________________ 50 Drawing _________________________________ 51 Tomogram _______________________________ 52 Drawing _________ , _________________________ 53 Tomogram _______________________________ 54 Drawing __________________________________ 55 Tomogram _______________________________ 56 Drawing __________________________________ 57 Tomogram ______________________________ 58 Drawing ________________________________ 59 Tomogram ______________________________ 60 Tomogram _______________________________ 62 Drawing ________________________________ 61, 63 Tomogram ______________________________ 64 Tomogram ______________________________ 66 Drawing ________________________________ 65, 67 Tomogram ________________________________ 68 Drawing ________________________________ 69 Photograph of specimen, lateral view __________ 72 Photograph of specimen, frontal view __________ 73 Photograph of specimen, inferior view _________ 72 Photograph of specimen, superior view, roof of calvarium removed ___________________ 73 Orientation of tomograms and drawings on paramedian schematic of cranium ___________ 75 A. Tomograms B. Drawings Tomogram _________________________________ 76 Drawing of anatomical section _______________ 77 Figure 5.8 Figure 5.9 Figure 5.10 Figure 5.11 Figure 5.12 Figure 5.13 Figure 5.14 Figure 5.15 Figure 5.16 Figure 5.17 Figure 5.18 Figure 5.19 Figure 5.20 Figure 5.21 Figure 5.22 Figure 5.23 Figure 5.24 Figure 5.25 Figure 5.26 Figure 5.27 Figure 5.28 Figure 5.29 Figure 5.30 Chapter 6 Figure 6.1 Figure 6.2 Figure 6.3 Figure 6.4 Figure 6.5 Figure 6.6 Figure 6.7 Figure 6.8 Figure 6.9 Figure 6.10 Figure 6.11 Figure 6.12 Figure 6.13 Figure 6.14 Figure 6.15 Figure 6.16 Figure 6.17 Figure 6.18 Figure 6.19 Figure 6.20 Figure 6.21 Figure 6.22 Figure 6.23 Tomogram Drawing . Tomogram Tomogram Drawing , Tomogram Drawing Tomogram Drawing , Tomogram Tomogram Drawing , Tomogram Drawing . Tomogram Drawing ,. Tomogram Drawing . Tomogram Tomogram Drawing ., ,. Tomogram Tomogram Orientation Tomogram Drawing of tomograms and drawings . . , Tomogram Drawing - , Drawing .. fl ,, Tomogram Drawing ._ , Drawing . Tomogram Drawing Drawing Tomogram , Drawing Tomogram Drawing Tomogram Drawing Tomogram Drawing Drawing Tomogram Drawing Page 180, 81 7 £39, 91 92 94 Q:,,;:§ i 95 ,._ 96 ,, __ _ 97 _____________________ 98 a“ 100 ,,299,101 ,_102 ._ _ 103 H- 107 , - 108 ._ 109 MA 110 - ,_111 ,-_111 N- 112 -2 _ 113 , 113 ”A” 114 W , 115 ,1“ 115 ,, a 116 , 117 118 119 , 120 , 121 122 123 123 ,_ 124 . 125 xi xii Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure 6.24 6.25 6.26 6.27 6.28 6.29 6.30 6.31 6.32 6.33 6.34 6.35 6.36 6.37 6.38 6.39 6.40 6.41 Tomogram Drawing , _ Tomogram Drawing Tomogram Drawing Tomogram Drawing Tomogram , , Drawing W , Tomogram Drawing , , Drawing , Drawing , Drawing Drawing , Drawing W, Drawing Page 126 127 128 129 130 131 132 133 134 135 136 137 138 138 139 139 140 141 CHAPTER 1 Introduction The cranium develops as a composite of bones which differ in embryologic origin and in mechanisms and patterns of growth and modulation of form. The BASIOCCIPITAL. EXOCCIPITAL, a portion of the SUPRAOCCIPITAL. the BASISPHENOID. PETRO- SAL and ETHMOID are preformed in cartilage. Growth of the BASISPHENOID. BASIOCCIPITAL, EXOCCIPITAL and the ehondral portion of the SU— PRAOCCIPITAL is principally at their cartilaginous synchondroses. until the cartilage is replaced by bone and bony fusion occurs. Thereafter. growth is only at their periosteal margins. The cartilage skeleton of the branchial arches is the origin of the auditory ossicles and the styloid process. Most of the cranial bones are membranous in de- rivation. The squamous elements enclosing the brain case. or calvarium. include the ALISPHENOID. the FRONTAL. the SQUAMOSAL and a portion of the SUPRAOCCIPITAL. These bones ossify peripheral- ward from one or a few centers within membrane units. Growth continues in irregular distribution. alternating with erosion, at most of their sutural approximations. so that they become interdigitated. They are further modulated in form by apposition or resorption at their inner and outer periosteal surfaces. And. like the rest of the skeleton. their internal trabecular arrangement is continuously adapted to physical stress. Of the membranous bones of the face. the NASAL and LACRIMAL are initially formed and later shaped in manner like the squamous bones of the calvarium. The MAXILLA. PALATINE and MALAR are formed from multiple ossification centers. but late in fetal life become a single bone. These major facial bones. and the MANDIBLE. undergo extensive growth and modulation of form during fetal and post- natal development. The external margins of the head. and of its oral and pharyngeal cavities. are smoothly contoured and these contours change subtly during fetal and postnatal development. But the components of the cranium change markedly in structure, in their relative size, in their spatial orientation and in the patterns of sutural approximation. The teeth are also in developmental progression. Radiography. and tomography in particular, give us strategic information about these sequential develop- ments. The radiographic criteria are multiplied by the differences in skeletal structure. Cartilage is conspicu- ously radiolucent. The cancellous matrix of ossified bones is less radiopaque than the cortex. The paranasal and paratympanie air cells are lucent. and marginned with radiopaque cortex. But the auditory ossicles and the ANNULUS remain relatively dense and radio- paque. The bony labyrinth. of distinctive non-trabecu- lar bone. and the adjacent bone of the petrous pyramid are distinctively dense. Radiographically. the tooth buds afford a variety of criteria. including the radio— dense enamel. the less dense dentin and the denser margin of the crypt. This multiplicity of radiographic criteria opportunity for greater discrimination of skeletal de— velopment in the cranium than in the limbs and trunk. But. at the present time. we are still largely dependent upon calibrations of development derived from stand- ardized radiography of dental maturation and skeletal epiphyseal maturation in the limbs and/or the trunk. The variety of skeletal changes in the cranium should be calibrated in relation to these other criteria of de- velopment. Such comparisons are needed to distinguish the rela— tive contribution of systemic factors vis—a-vis local determinants of growth and development in the cranium. The calvarium grows and develops rapidly in fetal life in correlation with the rapid growth of the brain. Criteria taken from the OCClPlTAL. SPHENOID and TEMPORAL composites are par— ticularly relevant to development of the brain stem. The facial skeleton grows and develops in correlation gives with enlargement of the pharynx and the nasal and oral chambers. The development of the portion of the cranium related to the cervical vertebrae and cervical musculature corresponds in general with that of the skeleton of the trunk. Parallel evaluation of the cranium and of other parts of the skeleton is. at the present time, the basis for the clinical distinction of generalized skeletal dis— orders from cranial abnormalities. Dyschondroplasia. for instance. is clinically more familiar in the limbs and trunk than in the cranium. But the dyschondro- plasias which result in the cranial distortions described by Crouzon and by Apert occur exclusively or prin- cipally in the chondrocranium. Likewise. systemic abnormalities of the bony skeleton. such as nephro- pathic and hypovitaminotic rickets are better defined outside of the head. But metaphysial. or craniometa- physial. dysplasia (Pyle). a failure of the osteoclastic element of modulation of form. is best detected in the cranium. Likewise. the skeletal correlates of hemolytic and iron deficiency anemias may first be recognized in the cranium. The hyperostosis of hypervitaminosis A and the lytic lesions of Gauchcr‘s disorder may selec— tivity involve the skull. Neoplastic lesions. such as leukemic infiltrations or the metastases of sarcoma may appear initially in the skull. The cranium is of particular clinical significance as it evidences regional disorders. These disorders are as varied as the developmental components of the head. The brain is liable to the greatest variety of develop— mental abnormalities. Some of the skeletal reflections of brain disorders are seemingly simple. For instance. the calvarium expands about a meningeal chamber which is abnormally expanded by hydrocephaly or macrocephaly. Reciprocally. microeephaly is associ— ated with microcranium. selectively involving the cal- varium. But the distortions of the cranium associated with certain patterns of brain hypoplasia may be more complex. Thus. in “anencephaly” a bifid and hypo- plastic brain is only partially enclosed by a markedly hypoplastic calvarium. But the more caudal skeleton. particularly that of the upper extremities. may be overgrown. Nafiagas (I925) interprets this juxtaposi— tion of hyperplasia to abnormal hypoplasia as evidence of the caudalward displacement of the cephalic insti— gation of growth. Most of the developmental distortions of the facial portion of the cranium are a part of regional abnor- malities as arrhineneephaly. or hypoplasia of the eye. or cleft of the palate and/or lip. These are initiated in embryo. and the mesenchyme generating the skeleton participates in the regional disruption. In this process, the variations of the embryonic neural and epithelial elements are probably determinant. Developmental distortions of the rhinencephalon are associated with severe and peculiar distortions of the facial skeleton. In severe arrhineneephaly. with absence of the olfac— tory apparatus. the nose is hypoplastic or absent and the face develops in relevance to the eyes. mouth and pharynx. In the circumstance of primary hypoplasia of the eyes. the skeletal orbits are small and abnormally shaped. The skeletal abnormalities of cleft palate and/or cleft lip extend to a variable degree and in variable direction to the nasal. orbital and basilar por- tions of the cranium. to the mandible and to the upper cervical vertebrae. Those abnormalities which are associated with motor impairment each influence skeletal development in specific and characteristic manner. In primary dis- orders of the motor unit. the individual’s pattern of muscular hypoplasia and fibrosis is associated with hypoplasia and deformation of the skeleton to which the musculature is attached. Analogous skeletal de- formation results if the central neurological lesion results in atony. Other patterns of skeletal deformation result if the neurological lesion results in a spastic form of dyskinesia. In summary. the heterogenously derived cranium is the site of expression of a variety of skeletal disorders. some of which are restricted to this region. The era— nium is also the site of expression of a larger variety of regional abnormalities. primary in brain and/or the peripheral innervation including the nose. eye and ear. More incidentally. certain portions of the cranium may evidence disorders which are principally of the motor system. This heterogeneity must be kept in mind as the clinician selects radiographic procedures to elucidate a particular “congenital abnormality" of the head. This heterogeneity of patterns of abnormalities in- volving the cranium is being elucidated by clinical experience. It is appropriate to mention the strategic significance of postmortem radiographic and anatomic studies in the circumstance of death of an infant who has demonstrable abnormality of the cranium. Exten- sive radiographic studies. followed by anatomical dis— section. will advance our understanding of these abnormalities. CHAPTER 2 Material & Procedures These demonstrations are of portions of 4 crania selected from 25 late fetal or early infantile specimens. Seven of these specimen crania were obtained from the collection of the Department of Anatomy, Univer- sity of Maryland School of Medicine, from a racially varied population. Eighteen crania were selected from the large stock of the National Biological Supply Com— pany. which had been obtained from sources of India. The specimens from each of these sources were of unidentified subjects. without information about gesta— tional or postnatal age, details of birth. clinical cir— cumstance of death or measurements of the cadaver. Mandibles were included. but no other portions of the skeleton were available. But. in common with most specimen infant crania, these had undergone postmortem distortion in form and general dimension. Accordingly. qualitative cri- teria. rather than measurements. were employed for estimation of developmental status. The crania from the commercial laboratory were prepared in routine manner by manual cleaning of detritus and by the spray application of a thin plastic covering. The crania from the Department of Anatomy were manually cleaned and were. in general. anatomically more com— plete. In most of the crania. the tympanic membranes were complete or nearly complete. Consistently among these specimen crania. the tympanic membrane. MAL— LEUS and INCUS were retracted from the position in which they are found in infant cadavers or in most living infants. Specifically. in approximately a diminishing order of significance. our externally evident criteria of ges- tational term status were: In the PETROSAL~The carotid canal is enclosed inferiorly. The fossa of the geniculate ganglion is nearly closed. The subarcuate fossa is partially closed at its orifice. The internal acoustic meatus is approximately 5—51/2 mm. deep. The pctrosquamo- sal suture is firmly closed by bony approximation. without fusion in its length in the tegmen. The anterior and posterior portions of the AN- NULUS are approximated; it has extended medial- ward. along the inferior aspect of the PETROSAL. and lateralward. along the superior and anterior aspect of the external auditory canal. In the BASISPHENOID. the anterior clinoid proc— esses incompletely approximate the midline. The dorsum sellae and the posterior clinoid processes are entirely chondral. The PTERYGOID is visibly fused or nearly fused with the medial pterygoid process. In the FRONTAL. the roof of the orbit is continu- ous. The supraorbital fissure is open within the supraorbital ridge. In the SQUAMOSAL. the mandibular fossa is only slightly concave. In the PALATINE. the posterior margin of the bony palate is slightly indented or is straight across the midline: there is no posterior nasal spine. In the MAXILLA. the length of the infraorbital canal is open to the orbit or. in some specimens. it may be enclosed at its anterior orifice. The anterior nasal spine is a distinct prominence. In the SUPRAOCCIPITAL the suture between its chondral and membranous portions is open only in its lateral portion. The posterior margin of the VOMFR approximates the anterior—inferior angle of the BASISPHFNOID. immediately adjacent to the rostrum. Radiological Procedures: The selected crania. with the upper portion of the calvarium removed. were fixed upon %” (91/2 mm) clear plastic by a layer of red orthodontic wax. The cranium rested on the occipital condyles and the mar- gin of the maxillary alveolar ridge. Variably in indi- vidual crania. the inferior margin of the tympanic ring approximated this plane. In this position, a line between “basion” and “anterior nasal spine” parallels the surface of the mount. The tomograms in the coronal and transverse plane were made on a North American Phillips Polytome. A hypoeycloidal pattern of tube and cassette motions was utilized with a standard six second sweep 281 cm in length. The depth of focus with this apparatus is 1.2 mm. The peak kilovoltage and milliamperage varied with the specimen under examination. The coronal tomoradiographic sections of Chapter 4 were made at intervals of 5.0 nnn anterior to the posterior clinoid processes and at 1.0 mm more posteriorly. to the middle of the foramcn magnum. The transverse sections of Chapter 5 were at 1.0 mm intervals. The most inferior section (Figure 5.6) is through the maxillary teeth. the EXOCCIPlTAL and the inferior portion of the pterygoid processes and the inferior portion of the PETROSAL. The most superior section is through the orbitosphenoid. the arcuate eminence of the PETROSAL and the superior portion of the nasal chamber. The sagittal sections of the otie region skeleton (Chapter 6) were made on a Profexray Gyrotome. The tube and cassette were moved in circular pattern with a 3 second exposure. The kilovoltage and milli- amperage were varied according to the specimen. Tomoradiographic sections were made at 1.0 mm intervals. Anatomical Procedures Following tomography. the calvarium was removed from the cranium and all periosteum and dura were stripped from the bones. Each tomogram was exam— ined for visible features which were sufficiently dis- crete to define the plane of the section. In some tomograms. a single anatomical detail sufficed to identify a plane; in others, two or more less defined landmarks were required. When the locations of the tomograms were established. these were marked on full-sized photographs of the skull. The cranium was coated lightly with wax and fixed in a rectangular wooden box. The anterior portion of the cranium selected for coronal sections was em- bedded in red acrylic. mixed in thin consistency. The mixture of embedding medium was first poured about the periphery of the cranium and then the orbits and the cranial vault were filled. The mass was extensively vibrated so that all accessible interstices were filled. The selected lines of section. marked at intervals of 5 mm on the cranium. were extended as lines upon the enclosing box. The box. block and cranium were then cut by a band saw. Figure 2.1 Drawing of cranium section embedded in stone. The matrix has been excavated to further expose the specimen. The portion of this cranium posterior to the pos- terior clinoid processes was embedded in yellow dental stone. The cranium, in its stone block. was sawn through the posterior portion of foramen magnum. It was then sanded in the coronal plane, in an anterior- ward sequence, in 1 mm. gradations. Sanding was done with a motor—driven dental model cutter: a water- coolcd rotating abrasive disc which is approximated by the specimen block sliding under manual control on a fixed platform. The stone block provided good mechanical control of the specimen and helped in maintaining stable orientation. As the sanding pro- gressed. the landmarks were sought which identified tomographic sections. The embedding materiel was excavated about the bone on the face of the cut which was to be drawn (See Fig. 2.1). Thus. the anatomical illustrations become somewhat three dimensional. demonstrating the bony anatomy in depth. But this technique of demonstration has resulted in the loss of certain anatomical details. such as the scroll-like por- tions of the nasal turbinals. The coronal sections of skeleton were prepared and drawn from caudal per- spective. The cranium studied in transverse plane was embedded in yellow dental stone. The stone block and the cranium were then sanded in transverse plane. in an inferim-superior sequence. Correspondingly. the successive anatomical illustrations are from inferior perspective. The crania demonstrated in coronal and in trans- verse sections were each slightly asymmetrical in rela- tion to the plane of section. These slight asymmetries, estimated at 0.5 to 1.0 mm., were shown in sawn or ground sections and are noted in the comments accom- panying the section illustrations. Fortunately, they often demonstrate additional anatomical information. The cranium selected for sagittal sectional demon— stration of the ear area was sawn in the midline and then coronally through the curve of the ALISPHE- NOID, slightly anterior to the round foramen. and coronally through the EXOCCIPITAL. posterior to the condyloid canal. The block was imbedded in the dental stone, leaving the median section plane slightly exposed. With this plane for orientation, the block and specimen were sanded in a medialward succession. approximating the tomograms at 1. mm intervals. be- ginning at the head of the MALLEUS and the body of the INCUS. Relating of Tomographic and Anatomic Sections. The “matching” of radiographic and sawn or sanded anatomic sections offered problems because of the basic differences in the method and anatomic content of demonstration. The radiographic tomograms dem- onstrate a “slice” or section of significant diameter. with diminishing discrimination of anatomic elements on either side of this. Whereas the anatomic sections are a surface. infinitely thin. except as its margins adjacent to the section are exposed by excavation of the embedding matrix. Thus. relatively lucent structures such as dental crypts or buds. or the various parts of the labyrinth, are often better shown in the tomograms. The sutures which are in cross-wise orien- tation to the tomographic section are more evident radiographically than in the anatomical section. par- ticularly if the suture is partially fused. Procedures of Illustrations and Descriptions The general radiographs and the tomograms were masked at the image margins. They were then loge- tronically intensified at a variety of discrimination se— lections and film developing procedures for optimal demonstration of selected details such as foramena, ossicles or elements of the labyrinth within the PETROSAL. The reference figures of the tomograms consist of line tracings and cut-outs of the radiodense areas in partially opaque overlay sheets. The drawings of these sections are precisely scaled. In drawing the initial sections, a projection and grid system was employed. Subsequently, the artists de- pended upon multiple caliper measurements. All sec- tions were drawn in magnification X 2. Drawings of the coronal and sagittal sections, of Chapters 4 and 6 respectively, are printed at this size. Drawings of the transverse sections, of Chapter 5, are printed at '/4 reduction; accordingly, these reproductions are at magnification X 1%.. The terminology is that Of the Third Edition (1968) of the Nomina Anatomica partially adapted toward common vernacular. Bones which are unfused at gestational term are separately designated, using designations which are established in developmental anatomy. Thus, the separate components of the TEMPORAL are named the PETROSAL, SQUAM- OSAL and ANNULUS. The OCCIPITAL is com- posed of the BASIOCCIPITAL, EXOCCIPITAL and SUPRAOCCIPITAL. The SPHENOID consists of the BASISPHENOID, ALISPHENOID, PTERY- GOID and, inconstantly. the BONES of BERTIN. The PREMAXILLA is demarcated from the MAXILLA. The INFERIOR TURBINATE is de- marcated from the ETHMOID. These separate bones are listed in the Anatomical Index under their general confluence and also singly. The separate bones are consistently printed in small capitals. The terms of spatial orientation and direction are interpolated from the mature human. as if the fetus were empirically gifted with the ability to stand in “anatomical position.” This usage is incongruous, but it is an empiricism which is essential for efiective communication with persons oriented to the anatomy of the mature human. Descriptions of these specimens are in comparison with the anatomical studies of the cranium of the human fetus, term neonate and infant by Crelin (1969). Elias (1971), and in a Symposium on De— velopment of the Basicranium (l976). And in com- parison with the radiographic descriptions of the cranium of the normal human infant by Cafiey (1973), Berkvens (1950). Chusler (1972) and Krogman and Chung (I965). The cranium of the infant has not been described previously in sectional anatomy or in radiographic tomography. But tomography of the adult human cranium, particularly of the temporal area. has been comprehensively illustrated and described by Holvey. Rosenthal and Anson (I945). Petersen and Stoksted ( 1951). Fischgold. David and Bregeat (1952). Fran- cois and Barrois ( 1952). Brunner, Petersen and Stok- sted (1961). Davcs and Loechel (1962). Valvassori (1963). Potter ( 1971). Binet and Moro (1972). and by Bennett. Brunner and Valvassori (1973). It is anticipated that the tomographic techniques employes in these studies will be displaced by the tech- niques of computerized axial tomography which are Figure 2.2 Schematics of cranium with indications of ana- tomic directions and planes. A. In frontal \‘lCW B. In lateral view SUPERIOR :NFERIO: 5UPERIOR—~> 'NFERIOR now becoming available. These new methods. recently reviewed by Ledley el (1/ (1974). Gordon et a/ (1975). New and Scott (1975). Robinson (1975). Prewitt ( 1976) and Webber (1976) etl‘ect superior anatomi— cal demonstration with significant economy of radia- tion. The anatomical portion of this atlas is. thus, a reference in anticipation of these further advances. 'RANSVEISE PLANE —> A bMEDIAL—fi LAYEIAL SAGITTAI. PLANE <— COIONAL PLANE 6 TRANSVERSE PLANE—F POSTEIIOR—> <——ANTEIIOI CHAPTER 3 Drawings of Reference Cranium This is the reference cranium of our project study. It is estimated at approximately term gestation by most of the criteria noted in Chapter 2. Figure 3.1 Drawing, frontal View Superior orbital fissure Optic foramen Supraorbital foramen PARIETAL : Lateral fontanelle LACRIMAL NASAL Nasal septum Middle CONCHA of ETHMOID ALISPHENOID INFERIOR CONCHA MALAR . Site of “anterior nasal spine” lnfraorbital canal Nasal process of MAXILLA Alveolar process of MAXILLA with dental buds enclosed Figure 3.2 Drumng. lateral View. and matching photograph Lateral fontanelle PARIETAL SQUAMOSAL FRONTAL .\ LACRIMAL ‘. N ASA], \ ‘ \ A (7) \ ’ v \ Nasal Process OfMAXILLA ’— ,5" 'Anterior Nasal Spine” Alveolar Process of MAXII.LA SUPRAOCCIPITAI. M ALAR Mastoid fontanelle EXOCCIPITAL Mastoid portion of PETROSAL Petrosquamosal suture Occipital condyle ANNULUS Zygomatic Process of SQUAMOSAL ALISPHENOID Lateral Pterygoid Process of SPHENOID 1' f I -: .~ m:.m WWWmmummmmunmmmmmlllmmul Figure 3.3 Drawing‘ superior view‘ roof of calvarium removed NASAL . .. ~ . .. Site of anterior nasal spine Alveolar process of MAXILLA \ ‘ Nasal process of MAXILLA \ ’ %/ Site of crista galli .v. 'W C? 1—— _ / ) Cribriform plate of ETHMOID —\ __ , FRONTAL Lesser wing of SPHENOID I { ALISPHENOID an? ‘ I Optic Foramen BASISPHENOID Anterior clinoid process Carotid groove Hypophyseal Fossa Oval and spinous foramena Site of sphenoccipital synchondrosis Pyramidal portion of PETROSAL BASIOCCIPITAL SQUAMOSAL _,r~ Site of “basion” l Hypoglossal canal \\C°"dyloid canal in EXOCCIPITAL Ml Foramen magnum Subarcuate fossa Arcuate eminence Petrosquamosal suture PARIETAL Internal acoustic meatus Mastoid fontanelle Q (:llondldl pOlthll Ol SUPRA()CCIPIIAI \ y‘ \ - ~\. Squamous portion of SUPRAOCCIPITAL -\ \ 3. 10 Flgure 3 .4 Drawing, inferior View, and matching photograph Anterior palatine foramen Site of anterior nasal spine 9/ Alveolar process of MAXILLA enclosing dental buds / Palatal process of MAXILLA MALAR \/ " Posterior palatine foramen Palatal processof PALATINE Site of “posterior nasal spine” ALISPHENOID Lateral pterygoid Posterior choana process of SPHENOID PTERYGOI D VOMER Zygomatic process of SQUAMOSAL Site of temporomandibular articulation BASISPHENOID Site of sphenooccipital synchondrosis Oval and SPinOUS toramena Carotid canal SQUAMosAL BASIOCCIPITAL Pyramidal portion of PETROSAL Site (’fiibaSion” Insertion of tympanum upon MALLEUS Occrpital condyle ANNuws ' ‘ ‘ ion of PETROSAL Foramen magnum Mastold port Jugular process of EXOCCIPITAL Hypoglossal canal Condyloid canal Mastoid fontanelle Chondral portion of SUPRAOCCIPITAI. Squamous portion of SUPRAOCCIPITAL ..... u— .... .— "' —. ... .- _. .— ._ — —- ' — .— .— .- a. .— .— —. c... — .— .— u... u. u... .— .- —-. — n..- _— —- — = .— a In. a “ .— n— a _ u— _ ~— .— .— —- .— — u- o- —- .- — — .- .- .— .— —. — 11 CHAPTER 4 l3 Figure 4.1 Photograph of cranium. lateral view Figure 4.3 Photograph of cruniunL infcrior vicw Figure 4.2 Photograph of cranium. frontal view Figure 4.4 Photograph of cranium superior View, roof of culvurium removed 15 1 6 Figure 4.5 Orientation of Sections ~7on superior aspect of cranium. roof of calvurium removed —on inferior aspect of cranium Tomogram 4.6 4.8 4.10 4.12 4.14 4.16 4.17A 4.17C 4.18 4.20 4.22 4.24 4.26 4.28 4.30 4.32 4.34 4.36 4.38 4.40 —— 4.42 4.44 4.45 4.47 4.48 4.50 Drawing 4.7 4.9 4.11 4.13 4.15 4.17D 4.19 4.21 4.23 4.25 4.27 4.29 4.31 4.33 4.35 4.37 4.39 4.41 4.51 SUPERIOR ASPECT INFERIOR ASPECT 17 Fl gure 4 . 6 * Tomogram Drawing ’l'his tomogram corresponds with the anatomical sec— tion of Figure 4.7. The LATERAL lNClSOR in its crypt is seen indistinctly on each side. The interfrontal and the frontonasal sutures are dis- tinct. Metopic suture NASAL Nasal process of AXILLA *'l'nmt>grams were taken ()f the cranium at 5 mm. intervals from the anterior plane (if the MEDlAl. DECIDUAL IN— (lSORs (Fig. 4.6) In that (if the pnsterim‘ margin of the VOMER him} palate (Fig. 4.22). 'lhe cranium mnuntetl in plaster @ was sawn at 5 mm, intervals enrresptinding to the tumo- eraphie plane (Hg. 4.7 In 4.23). ’l he tomograms and drawn seetiuns are presented here in Unempted MEDIAL INCISOR in alveolar process OfMAXILLA anterior tn posterior sequence. All drawings are from pos- teriur view. 1 8 Figure 4.7 FRONTAL Metopic suture NASAL Nasal process of MAXILLA SEPTAL CARTILAGE Alveolar process of MAXILLA Unerupted MEDlAL INClSOR This is the most anterior coronal anatomical section. It includes a portion of the alveolar process of the MAXILLA. The pos- terior margins of the DECIDUAL MEDIAL lNClSOR crypts are open. The bony sketeton of the external nose sectioned through the NASALs and through the nasal process of the MAXlLLA. The FRONTALS are sectioned at the base of the frontal eminence. 19 Figure 4.8 Tomogram Drawing 4.8 'l‘his tomogram dcmonstrzitcs structures 5 mm pos— terior to those of Figure 4.6. The crypt and bud ol' the ( USPlD are distinct on catch side. 'l'hc nasolacrimal canal is shown in much of its length. 'l'hc VOMER is shown its pztruincdizm plates which are not dcniarcatcd from the li'l'HMOlD or the MAXILLA. FRONTAL Cribrifonn plate of ETHMOID Nasal process Bud and crypt of PERM. LATERAL INCISOR SEPTAL CARTILAGE Nasal chamber Bud and crypt VOMER of DECID. Cuspn) DECID. LATERAL INCISOR Palatine process of MAXILLA Figure 4.9 Cribriform plate of ETHMOID LACRIMAL ’» .\ Nasolacrimal canal _, ' :' . ‘17: ». i . Nasal process of MAXILLA _. ‘3. . ‘ . - ,-, ~ .I' 12* ‘1 1- f a. 1‘ to s MAXILLA , ETHMOID Anterior palatine foramen The MAXILLA is sectioned on each side through the buds and crypts of the DECIDUAL LATERAL INCISOR and CUSPID and of the PERMANENT CUSPID. Its nasal pro— cess extends lateral to the LACRIMAL. The anterior palatine foramen is prominent. On the right, both lateral and medial walls of the nasolacrimal canal are shown. On the left. the LACRIMAL is sectioned farther anteriorly, and only the medial wall of the canal is shown. The FRONTAL is sectioned through the roof of the orbit immediately anterior to the perforated portion of the cribriform plate. F alciform crest SEPTAL CARTILAGE Middle concha of ETHMOID Nasolacrimal canal INFERIOR CONCHA Bud and crypt of PERM. CUSPID Bud and crypt of DECID. CUSPID Bud and crypt of DECID. LATERAL INCISOR VOMER The anterior tip of the VOMER is seen as a symmetrical thin plate. approximately transverse in orientation. The IiTHMOID is a continuous thin plate enclosing the nasal chamber laterally and superiorly and protruding into the cham- ber as the middle and superior conehae. The INFERIOR CONCHA is a bone of separate origin (the suture between the INFERIOR CONCHA and the ETHMOID is shown on the right). The SEPTAL CARTILAGE is commonly con- sidered a separate entity; in the infant. it is ossified only at its superior margin. The crista galli is also part of. the ETHMOID. 21 Figure 4.10 [J [J FRONTAL Cribril‘orm plate of ETHMOID Middle concha of ETHMOID (Orbit) Cells of ETHMOID Nasal process of ZYGOMATIC MAXILLA lnfraorbital canal Bud and crypt of Alveolar process of MAXILLA DEClD. MOLAR 1 Palatine process of MAXILLA Bud and crypt of PERM MOLAR 1 Tomo gram 4.10 Drawing 4.] 1 The calcified portion of ench DECIDL'AL MOLAR is conspicuous “ithin the lneent ehumber of its crypts. 'l'he portion of the MAXILLA between the nasal channber and the orbit is essentially n shell about the nntruni. lineh infrnorbitzil canal. in the floor of the orbit. is n lueeney surrounded by dense bone. Figure 4.11 SEPTAL CARTILAGE K Cribriform plate of ETHMOID FRONTAL Cells of ETHMOID "J" / Middle concha of ETHMOlD / lnfraorbital canal \ INFERIOR CONCHA <\\ ZYGOMATIC ’4‘. Nasal process of MAXILLA Bud and crypt of PERM. MOLAR 1 Sinus of MAXILLA Bud and crypt of DECID. MOLAR l Alveolar process of MAXILLA Palatine process of MAXILLA . VOMER Palatine process of MAXILLA 'lhe MAXILLA is sectioned through its alveolar. palatine. orbital and nasal processes. The bud and crypt of DECIDUAL MOLAR l and the bud of PERMANENT MOLAR l are well shown. The palatine processes meet at a median suture; they are distinguished from the VOMER and from the ETH— MOlD. 'l he lNFERlOR CONCHA is clearly demarcated from the El‘HMOlD on the right. The ethmoidal cells are prominent superior and lateral to the nasal chamber. at the base of the midd.e concha. The antrum occupies much of the mass of the MAXILLA between the nasal chamber and the orbit; the meatus of the antrum into the nasal chamber is not shown. 23 Figure 4.12 Superior concha of ETHMOID FRONTAL Cribriform plate Middle concha ZYGOMATIC INFERIOR CONCHA lnfraorbital canal Palatine process of MAXILLA Bud and crypt of DECID. MOLAR 2 Drawing 4.13 The bone between the nasal chamber and the orbit is essentially a delicate enclosure of the cells in the li'l'llMOlD and the antrum in the MAXILLA. In the palate and the adjacent medial wall of the MOLAR erypte the bone is radiographieally dense. 'l'he lateral wall 01' the orbit is formed by masses of eaneellous bone of the LYUOMATIC and of the FRONTAL. Figure 4.13 Cells of ETHMOiD Cribriform plate Superior concha FRONTAL of ETHMOID Zygomaticofrontal suture Middle concha ZYGOMATIC lnfraorbital canal MAXILLA INFERIOR CONCHA Bud and crypt of DECID. MOLAR 2 SEPTAL CARTILAGE This section demonstrates the relation of the oral and orbital elements which is distinctive in the infant, compared with the human adult: the molar portion of the alvelar process con— stitutes the floor of the orbit. The infraorbital canal is a shal— low indentation in that lloor. and also is a part of the wall of the MOLAR 2 crypt. 'l'he FRONTAL and ZYGOMATIC approximate at this level, compieting enclosure of the orbit. 25 Figure 4.14 Tomogram Drawing 4.14 4.15 This radiographie section demonstrates the small verti— eal dimension of the nasal area compared with adult. The nose is also simpler. with smaller eonehae and smaller ethmoidal cells. The paramendian plates of the VOMER extend about half of the vertical dimen- sion of the septum. The orbits are progressively narrOWer in medial direc- tion. They are continuous with the temporal fossa. Cribriform plate of ETHMOID FRONTAL L 6 £3) 0 ii... Crypt of MOLAR 2 VOMER Medial process of PALATINE 26 Figure 4.15 Cribriform plate of ETHMOID Falciform crest SEPTAL CARTILAGE ETHMOID FRONTAL (Orbit) Frontal process of ZYGOMATIC Superior eoncha of ETHMOID ZYGOMATIC ’4 Middle concha INFERIOR CONCHA Bud of MOLAR 2 Palatine process of MAXILLA Medial process of PALATINE This is the posterior portion of the MAXlLLA. The bud and crypt of DECIDUAL MOLAR 2 are sectioned in their pos- terior portion. And the section passes through the suture be- tween the palatal process corresponding medial of the MAX- lLLA and the PALATINE. The VOMER is a pair of simple vertical planes. The ETH- MOlD lines the nasal chamber laterally and superiorly, with protruding conchae. At this level, the roof of the orbit is superior to the cribil'orm plate. 27 Figure 4.16 Lesser wing of SPHENOID Optic foramen FRONTAL Superior orbital fissure ALISPHENOID / 0 Round foramen / Lateral pterygoid process VOMER Zygomatic process of SQUAMOSAL Medial pterygoid process Rostrum of BASISPHENOID 'l'his section is through thc postcrior chotmuc‘ the posterior t'orumcnu of thc orbit and the temporal fossil. ’l'hc optic t'orumcn is more distinct on tho right. whcrc it is laoumlcd by thc roots of thc lessor wing. 'l'hc suction is slightly tmtcrior to the superior orhitztl lissurc and thc round forumcn. 29 Flgure 4.17 A-D y . , . Tomogram Drawmg Supplementary coronal plane tomograms (A and C) and matching anatomical sections (B and D) from an 4.17A 4173 additional specimen. a separate SPHENOID bone. \\hieh developmentally approximates the specimen of (‘ltapter 4. Selected particularly for additional dent- onstt‘ation ol' orbitosphcnoid area. Figure 4.17 A 'l'omogram through lesser wing and body of BASI- SPHENOID. 'l‘hrough greater wing and lateral ptery- goid process of ALISPHENOID. 'l'he optic canal is well delined by the anterior and posterior wings. Note the relative lucency ot' the in— terior portion of the BASISPHENOID. 't he lateral pterygoid process‘ ol~ dense bone, is sharply outlined. Optic foramen Lesser wing Q /_ /_) \_/ i Q s / < Superior orbital fissure Round foramen Vaginal process Lateral pterygoid process 30 Figure 4.17 B Lesser wing BASISPHENOID Superior orbital fissure \\ Round foramen Optic foramen Marginol canal about vestige Base of lateral pterygoid process of craniopharyngeal tract Vaginal process This section is through the optic loramen close to the sulcus of the optic chiasm. the superior orbital fissure and the round l'oramen. The lesser wings. formed from symmetrical ossification centers. have not approximated in the midline. The inferior portion of the BASISPHENOID about the vestigc of the craniopharyngeal tract. and extending toward the articulation with ALlSPHE— NOlD, was friable and disintegrated during the grinding of the specimen. 31 Figure 4.17 C Tomogram 4.l7C Lesser wing Posterior root Chiasmatic sulcus _ of lesser wing L \ ) \ 4% 7/ Canal about vestige of craniopharyngeal tract /“ /\// Cgfi/ t \r\ ALISPHENOID Articulation of BASISPHENOID and ALISPHENOID LN l J Drawing 4.l7D 'l oniogi‘ani is through the junction of the optic canals \\ith the chiasniatic sulcu». 'l he canal about the wstigc ol~ the Ci‘aniophai‘yngcal tract is distinctly outlined. The articulation of the BASISPHENOID and i\l.lSl’llENOlD is an irregular bony coinzloincration. Figure 4.17 D Chiasmatie suleus Lesser wing / Posterior root of lesser wing Canal about vestige ., of craniopharyngeal tract Round foramen ALISPHENOID Section through the ehiasmatie sulcus and the posterior wing. The friable inferior portion of BASISPHENOID of this section, like that of IQB. disintegrated during the preparation. Figure 4.18 PARIETAL Chiasmatic suleus Optic canal Lesser wing of SPHENOID Round foramen Canal of vestige of craniopharyngeal tract ° \v c/ Lateral pterygoid process BASISPHENOID Medial PICFYEOid process and PTERYGOID Zygomatic process of SQUAMOSAL 34 Tomogram 4.l8 Drawing 4.19 'l'he BASISPHENOID is shaped radiograpliically as a broad rounded triangle. The central lucency ot' the canal about the vestige of the craniopharyngeal tract is in the form of an inverted V. The radiographie contour of the ALISPHENOID corresponds Closely with that in the corresponding anatomical section, including the site of the round l'oramen. The PTERYGOID is demarcated by suture from the medial pterygoid process. ’l'he lateral portion of the lesser wing. at the side of the eliiasmatie sulcus. is of dense bone. Figure 4.19 Lesser wing of SPHENOID iv PARIETAL Round foramen Optic canal Superior orbital fissure VOMER Pterygoid foramen Zygomatic process of SQUAMOSAI. PTERYGOID (fractured at tip) ALISPHENOID Lateral pterygoid process This section includes the BASISPHENOID. the ALISPHEN- OlD. the PTERYGOID. and the lesser wing. The canal about the vestige of the eraniopharyngeal tract (pouch of Rathkc) is prominent in the center of the BASISPHENOID. 'l'he ALISPHENOID is sectioned through its greatest mass. The expansion about the posterior orifice of the round lioramen indents the bone in this plane. The “wing-like” thin plate extends lateralward as the superior wall of the temporal fossa. The lateral ptcrygoid process is short and blunted, in the infant. In the young infant. the PTERYGOID is a separate bone ap— 7roximating the BASISPHENOID and ALISPHENOID and extending inl'eriorly as the hamulus (lost in this specimen. see Figure 3.3. The pterygoid foramen is located between the PTERYGOID and the lateral margin of the VOMER. The sulcus of the optic chiasm is superior to tthe BASISPHEN- ()ID and enclosed laterally and anteriorly by the lesser wing. The optic foramen extends anterolaterally from it. between the anterior and posterior roots of the lesser wing. Figure 4.20 Drawing 4.2] 'l'lie BASISPHENOH), ALISPHENOID and lesser ring are essentially identical in arrangement and mass \\llll the accompanying anatomical section‘ 4.21. PARIETAL BASISPHENOID ALISPHENOID Anterior clinoid process Zygomatic process Lateral pterygoid process 3 6 Figure 4.21 PARIETAL Tip of anterior clinoid process ALISPHENOID BASISPHENOID Orifice of vestige of craniopharyngeal tract Zygomatic process of SQUAMOSAL \ Lateral pterygoid process The ALISPHENOID and BASISPHENOID approximate at a simple suture. The lesser wing is represented by the posterior tip of the an- terior clinoid process. This section is through the hypophyseal fossa and the roof of the epipharynx. The BASISPHENOID is saddle-shaped. The superior orifice of the canal about the vestige of the hypophy- seal tract is immediately anterior to this section. 37 Figure 4.22 Tomogram 4.22 'l'lic mcdizin clcl't in the BASISPHENOID is prom— incnl. 'l‘llc opacity ol' the AlvlSPHliNOll) is also larger than in llic Iomogrum 01' l’igurc 4.20. rcllccting lhc contour of ilic bonc. which is ubliquc to the coronal plunc. PARIETAL Base of zygomatic process of SQUAMOSAL BASISPHENOID ALISPHENOID 9 Site of temporomandibular Oval foramen . articulation Carotid groove SQUAMOSAL BASIOCCIPITAL 38 Figure 4.23 PARIETAL ' - Site of carotid groove Site of sphenooeeipital synchondrosis Squamoparietal suture BASIOCCIPITAL SQUAMOSAL BASISPHENOID ALISPHENOID Base of zygomatic process \ Oval foramen Site of temporomandibular articulation This section is through thte approximation of the BASISPHEN— (ND and BASIOCCIPl’l‘AL. The posterior end of the BASISPHENOID has a median cleft. The posterior mass. or dorsum sellae. of the hypophyseal t'ossa is entirely chondral in the young infant, and is missing from the skeletal specimen. Likewise, the mass of the sphenooeeipital synchondrosis is diminished. Only the anterior lip of the BASISPHENOID is shown. The small plate of the ALISPHENOID joins the BASISPHE- NOID at a simple suture. The SQUAMOSAL is sectioned at the base of the zygomatie process. Figure 424* 'l he MALLEUS and the lateral wall of the tympunie unity are well shown in this tomogruni. 'l'he tegnien is less distinct than in Ioniogrunis more posterior. 'l'he lueeney of the cochlea is sharply outlined by dense hone. 'l he throoeeipitul suture. hetueen the BASICX‘CH’I— 'll-\l. and medial tip ol~ the PE’I‘ROSAL is well LlC- lineuted. Squamoparietal suture ' MALLEUS Tympanic cavity Apical whorl of cochlea Petrooccipital suture K /®/ Siteofround wmdow “lhe tomogrums and the corresponding unutoniie seetions posterior to the plzine of Figure 4.24 and 4.25 are each at approximately 1 mm. intervals. 40 Figure 4.25 Squamoparietal suture SQUAMOSAL Petrosquamosal suture in tegmen tympani Epitympamc recess Apical whorl of cochlea Semicanal of tensor tympani muscle H t ' i . ypo ympanlc recess Carotid canal ANNULus BASIOCCIPITAL The cochlea is sectioned through the anterior portion of the tympanic cavity. The tcgmen is thick and the epitympanie recess irregularly indents it. The tensor tympani muscle is well shown within its semicanal. The section is also through the anterior margin of the basal and apical whorls of the cochlea. e / Q L\. "' f W>R ff" g3“, :41?) 1/ 4l Figure 4.26 Head of MALLEUS Canal of facial nerve Apical whorl of cochlea Basal whorl of cochlea Petrooccipital suture BASIOCCIPITAL (Q Tympanic spur ANNULUS Site of tympanum Round window Drawing 'l'hc tcgnicn of tho tympanic cavity is not distinguish— ahlc in this tomogram. 'l‘hc l‘asal and apical “hurls of the cochlea arc sharply outlincd. The Hat BASIOCCIPI'I‘AL is oricntcd obliqucly to thc coronal planc and. hcncc. is ditl‘crcntly dcnion- strata] in the anatomical and radiographic sections. Figure 4.27 PARIETAL Petrosquamosal suture in tegmen tympani Squamoparietal suture Epitympanic recess SQUAMOSAL Margin of head of MALLEUS Basal whorl of cochlea Apical whorl of cochlea Tendon of tensor tympani muscle Hypotympanic recess BASIOCCIPITAL ANNULUS The ANNULUS is sectioned in its inferior portion. The MAL- LEUS is sectioned through its head. The tendon of the tensor tympani muscle is shown on each side. The tegmen of the tympanie cavity is thin. The apical whorl is sectioned close to the cupula. The canal of the facial nerve is shown at its hiatus at the site of the genieulate ganglion. 43 Figure 4.28 Tomo gram Drawi ng 4.28 \R 4.29 ¥x "Ii II '1 hc latcral wall of the tympanic cavity and the pos— terior portion of thc MALLEUS arc distinct. The hiatus of the facial canal is shown on the right. Two atljaccnt parts ol‘ the canaL adjacent to thc hiatus. are shown on the left. Epitympanic recess Tegmen tympani MALLEUS Canal of facial nerve Apical whorl of cochlea Petrooccipital suture BASIOCCIPITAL ANNULus Facial canal, hiatus Basal whorl of cochlea 44 Figure 4.29 PARIETAL Squamoparietal suture Petrosquamosal suture in tegmen tympani Epitympanic recess Tendon of tensor tympani muscle SQUAMOSAL Facial canal, hiatus Apical whorl of cochlea Basal whorl of cochlea I. MALLEUS ANNULUS BASIOCCIPITAL Hypotympanic recess The MALLEUS is sectioned through its posterior portion. The medial portion of the canal of the facial nerve lies superior to the cochlea. The lateral portion is in the wall of the tympanic cavity. The apical whorl of the cochlea is separated from the internal acoustic meatus by the thin cribriform lamina. The basal whorl is sectioned through its posterior margin. 45 Figure 4.30 Drawing \6 4.31 M “1i T omogram 4.30 r; l‘hc opacity ol' the bodics of thc lNCUS and MAI,— LEUS arc l'uscd in this tomogram. llic luccncy ol~ thc mcatus is combincd with that of the apical whorl. The luccncy ol‘ the anterior scmi— circular canal is also evidcnt Anterior limb of anterior semicircular canal Facial canal Falciform crest lntemal acoustic meatus Jugular fossa ;? - ~ BASIOCCIPITAL MALLEUS and [News V ANNULUS Hypotympanic recess 46 Figure 4.31 Petrosquamosal suture PARIETAL Tegmen tympani Squamoparietal suture Epitympanic recess Tendon of tensor tympani muscle SQUAMOSAL Facual canal lntemal acoustic meatus Apical whorl of cochlea (showing spiral lamina) Basal whorl of cochlea lNcus MALLEUS MALLEUS Hypotympanic recess ANNULus BASIOCCIPITAL The lNCUS and the neck of the MALLEUS are in this an— atomical section. The basal whorl of the cochlea indents the tympanic cavity as the promontory. The medial portion of the facial canal joins the internal acoustic meatus above the falciform crest. The lateral portion of this canal indcnts the tympanic cavity. 47 Figure 4.32 Tomogram ' PARIETAL Squamoparietal suture Efiitympanic recess Anterior semicircular canal MALLEUS and lNCUS Facial canal Anterior recess of vestibule Falciform crest in internal acoustic meatus .21.; Jugular fossa .. / K Promontory BASIOCCIPITAL Hypotympanic recess 48 fl H 4.32 / :,:;% % l'he bodies of the common opacity in 'lhe lateral portion the margin of the lateral semicircular Drawing \(A t‘\ 4.33 m I! MALLEUS and INCUS the tympanic cavity. ol~ the facial canal is visible in tympanie cavity, inferior to the canal. The anterior semicircular are “d canal is seen indistinctly. 'l'he internal acoustic meatus is fully demarcated. 'l'he jugular l‘ossa is bulbous in contour. Figure 4.33 PARIETAL Petrosquamosal suture Squamoparietal suture . Tegmen tympani E it m anic recess SQUAMOSAL p y p Facial canal Falciform crest in internal acoustic meatus Promontory over basal whorl of cochlea Basal whorl of cochlea CTN» » a: Neck of MALLEUS ANNULUS Jugular fossa BASIOCCIPITAL The. INCUS is shown in most of its length. The body of MAL- LEUS is in perspective: its neck is in the section. The facial canal indents the medial wall of the tympanic cavity. The faleiform crest is at its greatest prominence in the internal acoustic meatus. 49 Figure 4.34 Tegrnen tympani Epitympanic recess Anterior semicircular canal Vestibule Falciform crest lntcmal acoustic meatus Jugular fossa BASIOCCIPITAL Semicircular canal, lateral Body of Incus Lenticular process of INcus and Body Of STAPES Hypotympanic recess Oval window Tomogram In this tomogrum, the INC‘US and the head of the S'I‘Al’ES are outlined in continuity. 'l‘he luceney ol' the basal whorl overlies that of the vestibule. The anterior limb of the anterior semi— eireulztr eunztl is distinguishable in the urcuztte emin- enee. Figure 4.35 PARIETAL . Cells in SQUAMOSAL Petrosquamosal suture Squamoparietal suture Tegmen tympani Epitympanic cavity SQUAMOSAL Facial canal Falciform crest in internal acoustic meatus lntemal acoustic meatus Promontory Basal whorl of cochlea / K -\ .. ‘wmi WE ,/ ( ,WLeO’I/fjr'l' J 4) ._ "’3’ lNcus Lenticular process of INCUS / \ K I i \t ., ‘ i \ ‘ Handle of MALLEUS / y’ \_ ’ / ANNULUS Hypotympanic recess BASIOCCIPITAL J ugular fossa 'l‘his anatomical section is through the INCUS and the handle of the MALLEUS. 'l'he lympanic cavity is extended laterally into the SQUAMO— SAL by small air cells. The tegmen is thin. The portion of the internal acoustic meatus inferior to the falci— I'orm crest closely approximates the basal whorl of the cochlea. The promontory over the basal whorl and the ridge over the facial canal demarcate the indentation of the tympanic cavity toward the oval window. 51 Figure 4.36 Drawing In this tomogrant. the body of INCUS is shown. In thc PE'I'ROSAL thcrc is continuity of the luccncics of thc \cstihulc and ot' the posterior. lateral and anterior semicircular canals. The anterior canal is outlincd h)’ a portion of the arcuatc cmincncc. 'l'hc intcrnal acoustic mcatus is also well outlincd. PARIETAL / Squamoparietal suture / Tegmen tympani Anterior semicircular canal Vestibule lntemal acoustic meatus Jugular fossa Body of [mm Posterior semicircular canal Lateral Hyptoympanic recess semicircular canal U] [Q Figure 4.37 Cells in SQUAMOSAL /" E it in anic recess ' PARIETAL p y p Tegmen tympani / r l / Anterior semicircular canal : l S uamo arietal . . .- ’ q p Lateral semrctrcular canal ; , suture ( Facnal canal l. Elliptical recess of vestibule Spherical recess of vestibule , Falciform crest in internal acoustic meatus /_ x Footplate of STAPES in oval window ' Promontory SQUAMOSAL \\ Basal whorl of cochlea . . . A f ‘ , * Site ot “baston” . .z I) . » \. r. f- : ‘- lNcus , \ 7, ”V ’/ - l i, ‘ Neck of STAPES ’ i V I F Site of tympanic membrane BASIOCCIPITAL Ju ula f , . ANNULUS g r 088d Occnpitalcondyle EXOCCIPITAL This section includes the lNCUS and the neck of the STAPES. In the anatomical section, the thin partition between the in- ternal acoustic meatus and the basal whorl is perforated. The oval window, containing the footplate of the STAPES, is at the junction of the basal whorl and the spherical recess of the vestibule. The lateral and anterior semicircular canals extend from the elliptical recess. The lateral portion of the facial canal is seen in the wall of the tympanic cavity. 53 Figure 4.38 v Tomo gram Drawing 4.39 The lNCUS and STAPES are shown in continuity. The internal acoustic meatus is shallow. A greater extent of the lateral and anterior semicircular canal is shown than in the tomogram of Figure 4.37.The subarcuate fossa is discernable in the anterior face of the PETROSAL, as an indentation toward the superior semicircular canal. The hypoglossal canal is well shown in the EXOC— ClPlTAL. Aditus P ARIET AL Anterior semicircular canal Tegmen tympani Subarcuate fossa Anterior limb of lateral semicircular canal Vestibule lntemal acoustic meatus Jugular fossa “/"iii~,,§/ Hypoglossal canal lNcus STAPES Hypotympanic recess 54 Figure 4.39 ,7. Petrosquamosal suture / PARIET Al. Tegmen tympani / , Epitympanic recess [l ,’ S quamoparietal Anterior semicircular canal l ; suture Lateral semicircular canal Facial canal Elliptical recess of vestibule Spherical recess of vestibule Internal acoustic meatus Extension of labyrinth toward round window EXOCCIPITAL ‘ " . )mé t J .. . .1 2 \ ‘9‘ K {K \ ‘ “an . / Foramen magnum _ ,l; § , . .. _ ’ 4 (w « ,~ . . 1/ \ m. . .J V .f I e ’ <‘ j' \ ' . I . x. > ,4 . l l i\ Site of tympanum Footplate of STAPES in oval window; . ,» . / / / ANNULUS BASIOCCIPITAL . Ju ular fossa Hypotymipanic recess g ANNULUS Occipital condyle The anatomical section shows that the internal acoustic mcatus is skeletally separated from the basal whorl. The oval window is shown. The vestibule is extended toward the round window. The lateral and anterior semicircular canals are shown in fur— ther extent than in Figure 4.37. The STAPES and most of the INCUS are in the plane of the section on each side. The BASlOCClPlTAL now borders the foramen magnum. 55 Figure 4.40 PARlETAL Tegmen tympani Mastoid antrum . Anterior semicircular canal Squamopanetal suture Subarcuate fossa Lateral semicircular canal Vestibule lntemal acoustic: meatus Foramen magnum . H l l l Hypotympanic recess ypog ossa cana Jugular fossa 56 Drawing The tegmen of the tympanic cavity is shown more dis- tinctly than in the more anterior tomograms. The lNCUS and STAPES are in this plane. The vestibule and the 3 semicircular canals are shown. The subarcuate fossa is more distinct than in more anterior sections. The tomogram shows the hypoglossal canal in the EXOCClPlTAL; this is not seen in the anatomical section of Figure 4.41. Figure 4.41 , Petrosquamosal suture f PARIETAL Tegmen tympani ir- ' :l 3| Mastoid antrum _ _ . . . r . 5‘. Squamoparietal Anterior semrcrrcula canal suture Subarcuate fossa \ Lateral semicircular canal Vestibule Foramen magnum Extension of vestibule toward Hypoglossal canal round wmdow Facial canal J ugular fossa Extension of hypotympanic recess EXOCClPlTAL to round window The vestibule is now an isolated ovoid cavity. Extension of the vestibule toward the round window is shown on the right. The lateral portion of the lateral semicircular canal indents the tympanic cavity. The superior portion of the anterior semi- circular canal is within the arcuate eminence. On the left, the hypotympanic recess extends toward the round window. The recess also approximates the jugular fossa. The hypoglossal canal is seen in the EXOCCIPITAL. 57 Figure 4.42 PARlETAL Squamoparietal suture Tegmen tympani Mastoid antrum Anterior semicircular canal Vestibule lntemal acoustic meatus J ugular fossa H ypoglossal canal Lateral semicircular canal [Ncus Posterior semicircular canal Hypotympanic recess Facial canal 58 l'omogram Drawing 7%: flfl/ @ 4.42 4.43 Within the PETROSAL, the vestibule. the internal acoustic meatus. and the subarcuate l‘ossa are dis- tinguished. The lateral semicircular canal approxi- mates the lucency of the tympanic cavity. The an- terior semicircular canal is enclosed by the superior margin of the arcuate eminence. Figure 4.43 Pyramidal eminence (containing canal or stapedius muscle) / m SQUAMOSAL PAR‘ETAL Petrosquamosal suture in tegmen tympani . Anterior semicircular canal in arcuate eminence Squamotparietal suture Subarcuate fossa Lateral semicircular canal Vestibule Medial limb of posterior semicircular canal Hypoglossal canal ‘ {-3 V Foramen magnum J ugular fossa % Jugular process EXOCCIPITAL Occipital condyle In this anatomical section. the posterior limb of the lateral semicircular canal and the medial limb of the posterior semi— circular canal join the vestibule. The anterior semicircular canal is in the posterior portion of the areuate eminence about the subarcuatc fossa. The pyramidal eminence contains the canal of the stapcdius muscle. The EXOCClPlTAL contains the hypoglossal canal. It is ex— tended lateralward as the jugular process. 59 Figure 4.44 Tomogram V Drawing 4.44 4.45 4.46 ln this tomogram, the lateral and the anterior semi- circular canals are shown in continuity with the vesti- bule. And the subarcuate fossa is in continuity with the mastoid antrum. The hypotympanic recess is shown in the tomogram but not in the anatomical section. PARIETAL Squamoiparietal suture Mastoid antrum ubarcuate fossa Lateral semicircular canal Anterior semicircular canal / Vestibule / Jugular fossa ,..- " Y Q :3 Hypotympanic recess / \ Foramen magnum Petrooccipital suture H ypoglossal canal EXOCCIPITAL 60 Figure 4.46 SQUAMOSAL Petrosquamosal suture in tegmen tympani Mastoid cells Antrum Subarcuate fossa PARIETAL Posterior limb of anterior semicircular canal i; . Squamoparietal ' suture Posterior limb of lateral semicircular canal Common limb of anterior and posterior semicircular canals Inferior limb of posterior semicircular canal Hypoglossal canal \/ Foramen magnum Petrooccipital suture Jugular process Occipital condyle This anatomical section demonstrates the relation of the three semicircular canals immediately posterior to the vestibule. The lateral canal is sectioned through its posterior portion. The posterior canal is shown at its common crus with the anterior canal. The posterior portion of the subarcuate fossa extends nearly to the mastoid antrum. The hypoglossal canal is a shallow indentation on the medial aspect of the EXOCClPlTAL. The jugular process approxi- mates the PETROSAL at the petrooccipital suture. 61 Figure 4.45 Squamoparietal suture Tegmen tympani PARIETAL Mastoid antrum Lateral semicircular canal Subarcuate fossa Anterior semicrrcular canal Vestibule J ugular fossa ) Hypoglossal fossa @/ / Foramen magnum Jugular process SK Hypotympanic recess \ Petrooccipital suture 62 Tomogram )_/ Drawing 4.46 The anterior and the lateral semicircular canals are in continuity with the vestibule. The lucency of the subarcuate l'ossa is in continuity with that of the mas- toid antrum. The hypotympanic recess is incompletely distinguishable. The PETROSAL now approximates the. jugular pro- cess of the EXOCClPlTAL, at the petrosquamosal suture. The liypoglossal canal is a shallow indenta- tion in the EXOCCIPlTAL. Figure 4.46 Petrosquamosal suture in tegmen tympani Mastoid cells Antrum Subarcuate fossa PARIETAL Posterior limb of anterior semicircular canal Squamoparietal Posterior limb of lateral semicircular canal SUIUI‘C Common limb of anterior and posterior semicircular canals Inferior limb of posterior semicircular canal Hypoglossal canal SQUAMOSAL Petrooccipital suture J ugular process Foramen magnum Occipital condyle Sec legend on page 61. Figure 4.47 Tomogram V Drawing \C 4.47 4.48 ¢ "1 " 4.49 PARIETAL / Squamoparietal suture Tegmen tympani Mastoid antrum / Posterior limb of anterior semicircular canal /7/ Vestibule Jugular fossa (L) Hypoglossal canal / \\ Hypotympanic recess \ Foramen magnum Occipital condyle Petrooccipital suture EXOCCIPITAL 64 The vestibule and the hypotympanie recess are evident in the tomogram. though not in the corresponding anatomical section. Figure 4.49 SQUAMOSAL Petrosquamosal suture Mastoid cells Antrum PARIETAL . Margin of subarcuate fossa Squamoparietal suture . . . _ . Posterior limb of posterior semtcnrcular canal Recess of endolymphatic sac i} I \ _‘ \ ‘ \ Jugular fossa .\ i "- Petrooccipital suture ' Foramen magnum EXOCClPlTAL The only element of the labyrinth shown in this anatomical section is the posterior limb of the posterior semicircular canal. The recess of the endolymphatic sac is medial to the curve of this canal. The aqueduct of the vestibule is not visualized on these sections due to its obliquity to the coronal plane and its very narrow contour‘ The vestibule is slightly evident in the tomogram. The tympanic cavity is represented only by the mastoid antrum and cells. The tegmen is a thick shelf of bone. 65 K Figure 4.48 Drawing 4.49 The posterior limb of the posterior semicircular canal and the recess of the cndolymphatic sac are outlined by dense bone. But most of the lateral portion of the PETROSAL is canccllous: Accordingly, the margins of tlic antrum and ol' the subarcuatc mossa are not well distinguished in this area. PARIETAL Squamoparietal suture Petrosquamosal suture Tegmen tympani Mastoid antrum Posterior semicircular canal Posterior recess of vestibule Recess of endolymphatic sac / J ugular fossa ( Hypoglossal canal / Petrooccipital suture Foramen magnum EXOCCIPITAL () 6 Figure 4.49 Petrosquamosal suture Mastoid cells Antrum PARIETAL . Margin of subarcuate fossa Squamoparietal suture Recess of endolymphatic sac SQUAMOSAL '- ,‘ ' " /Jugular fossa \ 5C :\ (”A \ _“"| Petrooccipital suture ‘ X j \/ F oramen magnum EXOCCIPITAL Sec legend in page 65. Posterior limb of posterior semicircular canal 67 Figure 4.50 Tomogram Drawing ”7? MR \C 4.50 ‘ 23:, : , ¢ m. 4.51 l l l \ The tomogram corresponds closely to the anatomical section to Figure 4.51. PARIETAL Squamoparietal suture Petrosquamosal suture Mastoid antrum Posterior semicircular canal /Recess of 'endolymphatic sac '0' Occipital condyle / \ CB Petrooccipital suture Foramen magnum EXOCCIPITAL ()8 Figure 4.51 SQUAMOSAL ' PARIETAL Petrosquamosal suture Mastoid cells Squamoparietal suture Antrum Posterior limb of posterior semicircular canal ExoccmTAL Foramen magnum The PETROSAL is a bony mass except for the posterior margin of the posterior semicircular canal and the posterior end of the mastoid antrum. The recess of the endolympathic sac is shallow. The portion of the bone superior and medial to the mastoid antrum is loosely cancellous. The SQUAMOSAL is a vertically short projection between the PETROSAL and the PARIETAL. 69 CHAPTER 5 Figure 5.1 Photograph of specimen. Izltcrzll vicw Figure 5.3 Photograph of spccimcn, inferior vicw 72 Figure 5.2 Photograph of spccimcn. frontal view Figure 5.4 Photograph of spccimcn, superior View, roof of culvurium rcnlovcd I'L Flgure 5.5 Orientation of tomogrums and drawings on paramedian schematic of cranium DRAWING 75 Figure 5.6 Alveolar process of MAXILLA Palatine process of MAXILLA Pterygopalatine canal . Site of “posterior nasal spine“ Medial pterygoid process BASISPHENOID' Site of sphenooccipital synchondosis Carotid canal ANNuLus Tympanic Cavity ANNuLus BASIOCCIPITAL H ypoglossal canal R 76 ZYGOMATIC Palatine process of PALATINE This tomogram corresponds with the drawing of Figure 5.7 In the MAXILLA, the premaxillomaxillary suture is shown more distinctly than in the drawing. The lucency in the area of the bony palate demonstrates the nasal chamber in compari— son with surrounding bone. The dental buds are conspicuous, with the dense opacity of the enamel caps contrasting with the lucency of adjacent dental pulp and the surrounding crypt. The palatal process of the PALATINE appears as a homo— geneous transverse area. lts lateral extension is demarcated from the medial pterygoid process by a suture. The pterygoid apparatus is the only sphenoid element in this section. The lateral and the medial ptcrygoid processes are demonstrated as exaggerations with a common opacity. The PTERYGOID bone is not separately distinguishable. The EXOCClPlTAL is sectioned through the condyloid proc— ess on the right and through the hypoglossal canal on the left. The variable condyloid canal is distinguishable on either side of this specimen. The BASIOCCIPITAL and the SUPRAOCCIPITAL are in perspective. The course of the carotid canal within the medial portion of the PETROSAL is shown on the left. On the right. its emerg— ence from the apex of the PETROSAL is shown and also an area of lucency at the opening of the canal on the inferior aspect of the PETROSAL. The ANNULUS is distinct. The body of the MALLEUS is indistinctly seen on the right. Site of premaxillomaxillary suture Anterior palatine foramen MEDIA!" INCIS'OR LATERAL lNClSOR N c “ Crypt and bud of CUSPID Crypt and bud ofiMOLAR ] ‘ MOLAR 2 Pterygomaxillary fissure Dorsal palatine foramen Oval foramen / ‘ Lateral pterygoid process Spinous foramen I Site of 'auditory canal ‘ ‘ ANNULUS - Carotid canal ANNULUS J ugular fossa Supraoccipital notch SUPRAOCCI PlTAL Figure 5.7 Tomogram Drawing 5.6 —— 5.7 This first transverse anatomical section should be examined in comparison with the photograph of the cranium from its inferior aspect (Figure 5.3) and with the ventral reference cranium drawing. Figure 3.3. There is a lateral asymmetry in this section: the anatomical right (R) being slightly inferior to the left (L) side. This section shows the unerupted decidual teeth on each side of the MAXILLA; MOLAR l (R) has been lost. The dental crypts are rounded in internal contour; their walls are thin and delicate; the partition between the MOLAR crypts on the right is incomplete. The external walls of the left CUSPlD and MOLAR l crypts are broken. The suture demarcating the PREMAXlLLA. bearing the lNClSORS. is faintly visible in the transsected alveolar bone. Fine perforations are indicated Anterior nasal spine Site of premaxillomaxillary suture \ ” 3.. Bud and crypt of Cosmo Cribrifenn area in palatal process of MAXILLA CFYPI of MOLAR 1. ’ . .' ”‘" xx: . ll « Bud and crypt of MOLAR 2. Medial process of PALATINE Posterior nasal spine VOMER fl ‘. Medial pterygoid process —.——‘—o—— 5‘ ,4”~ , 0 } BASISPHENOID M ALISPHENOID Site of Sphenooccipital synchondrosis % BASIOCCIPITAI. \ H I :1 'l X. ,/ ypog ossa Cana ML)», ,/ j t \ I l Condyloid canal /: R SUPRAOCCIPITAL J'I" w“: in the cribriform area of the palatine process; the bone which has developed more recently is streaked radially. Both the palatine processes and the lateral processes of the PALATINE are well shown. The lateral process, transsected at its base. extends along the lateral aspect of the junction of the nasal chamber and pharynx. at the posterior choanac. The BASlSPHENOlD is seen in perspective. between the VOMER. anteriorly. the sphcnooccipital synchondrosis. pos- teriorly. and the medial pterygoid processes, the PTERYGOID bone and the ALISPHENOID. laterally. The PTERYGOID on the right is sectioned slightly superior to the hamulus; note its sutural junction with the medial pterygoid process. The lateral pterygoid process is also see- tioned on the right. The section on the left. at slightly superior level. is through the ALISPHENOID superior to the origin of the lateral pterygoid process. The EXOCClPlTAL is sectioned through the hypoglossal fora- mcn and. on the left. also through the condyloid canal. which is inconstant among different specimens. The mass of the PETROSAL borders the anterior lacerated foramen on its anterior aspect and the jugular fossa on its pos- terior aspect. Buried portion of the styloid process and the stylomastoid portions of the facial canal are approximated in cross—section in the mastoid process. The anterior flange of the ANNULUS extends along the PETROSAL. MEDIAL INCISOR Lateral INCISOR — ,/. ., Xi/j/ CUSPIDln crypt MOLAR [I in crypt Dorsal palatine foramen Site of auditory canal 1/, i / ‘ ‘ Carotid canal / ANNULUS J“ . ‘ < i 5‘ MALLEUS(ln perspective) " g. \. ,\\ lNCUS (In perspective) . I}, ‘ _ "mt . . r 4 ,‘ Hypotympanic recess ' , of tympanic cavity ANrsULUs Stylord process Stylomastnid forarnen Jugular fossa Jugular process EXOCCIPITAL Site of synchondmsis L 77 Figure 5.8 The elements of the MAXILLA closely resemble those shown in the tomogram of Figure 5.6, l.mm inferior. The premax- illomaxillary suture is more distinct. The maxillopalatine suture at the posterior end of the alveolar ridge can also be discerned. The decidual teeth and their crypts are similar to those in Figure 5.6. The bud of the permanent CUSPlD is now shown on the right. The median suture between the palatal processes of the PALA- TlNE is distinct. The pterygomaxillary fissure is better shown on the left, in the area of the pterygopalatine suture. The pterygoid processes closely resemble those in Figure 5.6. The EXOCCIPITAL is sectioned through the hypoglossal canal on each side. posterior to the synchondrosis between the BASIOCCIPITAL and EXOCCIPITAL and anterior to the condyle. ’l‘he inferior margin of the BASIOCCIPITAL is in perspective; the reference point “basion" is indicated by a curved wire. The inferior margin of the SUPRAOCCIPITAL is in perspective. The densely opaque ANNULUS outlines the tympanic cavity; this section is at the level of the hypotympanic recess. The area of the oval window is indicated by a lueency in the PETRO- SAL. The curved channel of the carotid canal is visible in the medial portion of the PETROSAL. with a lucent slot at its penetration of the apex. DECID. MEDIAL TNCISOR DECID. LATERAL INCISOR Bud and crypt of CUSPID Bud of PERMANENT CUSPID Crypt of MOLAR l Crypt of MOLAR 2 Pterygopalatine suture ZYGOMATIC Palatine process of MAXILLA Medial process of PALATINE Pterygomaxillary fissure Medical pterygoid process and Pram/Goa) Lateral pterygoid process Nasal spine, posterior Lateral pterygoid process _ BASXOCCIPITAL Site of sphenooccipital synchondrosis . Carotid canal Carotid canal Hypotympanic recess ANNU LUS Vestibule and Jugular fossa oval window Site of synchondrosis H ypoglossal canal Occipital condyle Mastoid fontanelle EXOCCIPITAL SUPRAOCCIPITAL 78 Figure 5.9 Tomogram Drawing 5.9 5.8 v ‘NJ The left side of this transverse section is 1—2 mm. inferior to the right. The section on the right is precisely through the thin cribril‘orm portion of the palatine process of the MAXILLA. while that on the left is immediately inferior to it. The INCISORs and their crypts are sectioned through their bases on the right. and through the apices of their crypts on the left. The bud of the PERMANENT MEDIAL lNClSOR is shown on the left. The MOLARs which are present (R2 and Ll and 2) are sectioned through their crowns. The lateral process of the PALATINE is well shown on each side of the posterior choanae. The processes extend posterior- ward to the medial ptcrygoid process. Between the lateral process and the MAXlLl.A is the groove of the pterygomaxil— lary lissurc. which is continued inl'criorly as the posterior pala— tinc foramen (see 5.7). The interior aspect of the BASlSl’HENOlD is shown in per— spective. On each side. the pterygoid process is demarcated by suture from the ALlSPHliNOlD. The ALISPHENOID is see— tioned through its ventral portion. The oval and spinous fora- mena are not yet separated by skeleton. In the center of the sectioned BASIOCCII’ITAL is a curved channel about the vestige of the notochord. The EXOCCIPI— 'l‘AL is sectioned through the hypoglossal canal on each side and through a margin of the condyloid canal on the left. The SUPRAOCCIPITAL is sectioned through its chondrally— derived inferior portion. superior to its median fissure; a shal- low notch. continuing this fissure. is seen on its posterior aspect. The PFTROSAI. margins the anterior lacerated foramen and the jugular fossa. At this level. the carotid canal is oblique within the anterior margin of the bone. adjacent to the site of the auditory canal. The basal whorl of the cochlea is shown and also the extension of the labyrinth toward the round window. The ANNULUS outlines the hypotympanic recess of the tympanic cavity. The junction of the tympanic cavity with the auditory canal is at this level. The promontory over the basal whorl of the cochlea protrudes in the medial wall of the tympanic cavity. The slender handle of the MALLEUS is shown. Bud ol' l’I-RM. MI:I)IAI |N(‘Isok A nterior nasal spine MLDIM lN(‘IS()R. lAll-RAI th Isok \ Bud and crypt ot‘CUsI’II) \ Crypt of Moi AR 2 Vow R / Medial ptcrygoid process / B/xstsmtmon) / / l’elrosal process Site of sphenooccipital synchondrosis . r g B.«s|oc(’n*| I Al // .. Site of vestigc of notochord / I Sitcol‘s nchomlrosis i / / Y 5» )_/ Hypoglossal canal W %/ l-lxot't‘li'l I Al ; (‘ondyloitl canal / SUPRAU('('II’llAl Lateral process of PA! Al INI- Medial ptet'ygotd process luamtm I(‘ / At ISI‘HENOII) /‘ ’ Zygomatic process of'l‘iammkm Site of temporomandibular articulation l‘oramena ovale and spinosum Semicanal tor tensor tympani muscle (‘arotid canal Site nfjunction of auditory canal with tympanic cavity ANNUI us Basal whorl ol~ cochlea Promontory over hasal whorl of cochlea ‘ b \ Y ((VJ MAI l tos " \\IN('US (in perspective) e, ANNUI US Round window Extension of vestibule ttmard round window Vestige of styloid process " Site of endolymphatic sac Site of synchondrosis 79 Figure 5.10 Bud of MEDIAL lNClSOR Bud of LATERAL lNCISOR Bud of CUSPID / v Bud of MOLAR I Palatine process of MAXILLA . Qt a Medial process of PALATINE m / Bud 0f MOLAR 2 ‘ o . . l J ‘ . ZYGOMATIC Lateral process of PALA1 lNE ‘ , . I‘ > / () BASIOCCIPITAL Pterygomaxnllary fissure e v ‘ Oval and spinous foramena Carotid canal, in apex of pyramidal Medial pterygord process ' ’ portion of PETROSAL Sphenosquamosal suture Lacerate foramen Lateral pterygoid process ‘I Site of auditory canal BASISPHENOID /./ / ANNUl.us Carotid canal ’ ’ 0 lNcus Site of notochord I u ‘ Apical whorl of cochlea Oval window .i.’ S/IAPES NNULUS Site of“basion" ' Q ‘ EXOCCIPITAL < Foramen magnum 8O Oval window Vestibule Facial canal Basal whorl of cochlea J ugular fossa Site of synchondrosis Tomogram 5.l0 This tomogram is through the palatine processes of the MAX— lLLA; the median suture of these processes is discernable against the opacity of the base of the VOMER. The lNClSORs and the right CUSPlD are sectioned through their bases. The palatal process of the PALATINE is sectioned at its su- perior margin. The lateral process is demarcated by the pterygo- palatine suture. The pterygopalatine canal is best shown on the right. The lateral and medial pterygoid processes are radiographieally sectioned near their base. and less sharply outlined. The com— bined oval and spinous foramena are well outlined. The irregular luceney seen in the center of the BASIOCCIPI~ TAL probably corresponds with the vestige of the notochord found at this site (see Fig. 5.9). The site of the synchondrosis between the BASTOCClPlTAL and EXOCClPlTAL is dis- tinct on the right. The site “basion” is marked with a piece of wire. The emergence of the carotid canal from the apex of the PETROSAL is indicated by a notch. The luceney of the cochlea is diseernable adjacent to that of the carotid canal within the PETROSAL. The hypotympanic recess is in this plane; the extension of this recess toward the round window is seen on each side. The body of the MALLEUS is seen indistinctly. on the right. 81 Figure 5.11 In the alveolar portion of the MAXlLLA are the crypts ot' the MEDIAL lNClSORs, and the buds and crypts ot' the PERMANENT LATERAL lNClSORs. The MOLARs and their crypts are as in Fig. 5.10. The orbital process is now shown. And the maxillozygomatic suture on the right. The lateral process of the PALATlNli is well demarcated by the pterygopalatine suture on each side. The pterygomaxillary fissure is better demonstrated on the left. This is the most inferior level at which the VOMER can be distinguished: as a median strip, overlying the median suture of the palatine processes ol~ the PALATlNE. and as para- median opaque lines. of the lateral processes. The pterygoid processes are radiographically indistinct. at their junction with the ALlSPHENOlD. This section is at the superior margin of distinct delineation of the foramen magnum. The central luceney in the BASIOCCIPI— TAL at the site of the embryonal notochord is expanded into a less distinct area. The EXOCCIPITALS are sectioned su- perior to the hypoglossal canal. The carotid canal appears as a notch in the anterior aspcct of the apex of the PETROSAL. The cochlea and the extension of the vestibule toward the round window are shown as subtly marginned lucencies within it. The cochlea is marginally dis— tinct. The lateral arch of the lateral semicircular canal is well shown. The carotid canal is less distinct. The site of the auditory canal is delineated in this section. at its junction with the tympanic cavity. The anterior portion of the ANNULUS is conspicuous. The body of the MALLEUS and of the INCUS are marginally distinct. Crypt of MEDIAL INCISOR Site of “anterior nasal spine“ BUd 0f CUSP'D SEPTAL CARTILAGE, between lateral processes of VOMER Bud of MOLAR l Bud of MOLAR 2 Bud of PERMANENT MEDIAL [NCISOR lnfraorbital notch . VOMER Pterygomaxrllary fissure ZYGOMATIC " ‘ . Inferior orbital Lateral process of PALATINE ‘ W” fissure Medial pterygoid process . \ Sphenooccipital synchondrosis . ' ‘ . Lateral pterygoid process \' ‘ ) Cgftld:an:l at of ALISPHENOID )’ ,\ L Ieo au itory can Site of lacerate foramen . 3 Apical whorl of cochlea Sphenosquamosal suture — ~_. - ?\‘- ANNULUS Spinous and oval foramena P t ANNULUS 1‘ mm" cry 5' ~ — ‘ MALLEUS rte of auditory canal '7 ’ Basal whorl of cochlea MALLEUS (It 1 . lNcus lNcus ii? Carotid canal |“ Vestibule Hypotympanic recess Petrosquamosal suture Petrosquamosal suture Cochlear canal Jugular fossa Syncho . osis Site of vestige of notochord Figure 5.12 Tomogram Drawing 5.12 l‘he MOLAR portion of the maxillary alveolar pro- cess is located between the nasal chamber and the pterygoid space. and inferior to the orbit. The maxil- loethmoidal suture is fused at this transverse plane. though the thin lateral wall is distinguished from the MAXILLA in the corresponding tomogram (see Fig- ures 5.10 and 5.11. The INFERIOR CONCHAE appear in this specimen only as simple curved flanges; their scroll-like periph- eral portions were lost in the preparation. The lateral process of the PALATINE is shown in its posteriorward extent on the left. On the right. its extension toward the medial pterygoid process and Middle concna of ETHMOID tin perspective) Ethmomaxilla suture ry INFERIOR CONCHA Lateral process of PALATINE PlekYGOID BASIOCCIPI‘I A1. Carotid Canal (in perspective) Apical whorl of cochlea ANNULUS . . / Extension of vestibule toward round Window Site of synchondrosis Jugular fossa EXOCCIPITAL SEPTAL CARTILAGI; Semieanal for .tensortympanimuscle _ 1 J ( Posterior cranial fossa ) the separate PTERYGOID is interrupted. The thin paramedian processes of the VOMER margin the SEPTAL CARTILAGE; these show postmortem distortions of form. The anterior tip of the VOMER is lost in the preparation. Posteriorly. the VOMER continues as a curved shelf. extended lateralward by symmetrical alae. The apical and basal whorls of the cochlea are shown on each side. On the left. the basal whorl bulges into the tympanie cavity as the promontory. On the left the vestibule extends toward the round window. All of the OSSICLES are represented at this level on the right. The handle of the MALLEUS is seen in cross section. The long process of the INCUS articu- lates with S'l‘APES. S'l‘APES is shown entirely: the head (at the articulation). the 2 crura. and the foot— plate. in the oval window. The BASlOCClPl'l‘AL is arch-shaped in this section; the median notch in its dorsal margin and a faint median line in the cancellous bone indicates the site of fusion of bone derived from the 2 paramedian hemicenters. Only the limb of each EXOCCIPITAL superior to the hypoglossal canal is shown. The por- tion of the SUPRAOCCIPITAL derived is chondral in origin. Margin of bud of PERMANENT LATERAL INCISOR Margin of bud of PERMANENT CUSPID Crypt of CUSPID Bud of MOLAR 1 Bud of MOLAR 2 VOMER ZYGOMATIC / ALISPHENOID Sphenosquamosal suture Middle cranial fossa Carotid canal Site ofjunction of auditory canal and tympanic cavity ANNoLus MALLEUS ANNuws INCUS STAPES Promontory Apical whorl of cochlea Basal whorl of cochlea Mastoid fontanelle Figure 5.13 In this tomogram, the MAXILLA on either side consists of the alveolar and the orbital processes, the latter extending lateralward to the ZYGOMATIC. Within the alveolar process are the bud of the PERMANENT CUSPlD, and the buds of the DECIDUAL MOLARs and their crypts. The lateral process of the PALA’I‘INE is well demarcated from the MAXILLA; the pterygomaxillary fissure is shown on the left. The VOMER is sectioned through its paramedian vertical processes and alae. The lateral wall of the ETHMOlD is demarcated from the MAXILLA. particularly on the right. The portion of the IN— FERIOR CONCHAE are best distinguished as that portion of their scroll—like contour which extends vertically from the transverse base. The ALISPHENOID and BASISPHENOID are broadly sepa— rated at their suture. shown here on the right. In this and in more superior radiographic sections, only the posterior rim of the SUPRAOCCIPITAL is shown. The internal acoustic mcatus slightly indents the PETROSAL on the left. but is shown in most of its length on the right. Within the PETROSAL‘ the apical whorl of the cochlea is demonstrated on each side. The vestibule and the inferior limb of the semicircular canal are shown on the left. These and part of the lateral semicircular canal are shown on the right. The MALLEUS is shown indistinctly on the left and distinctly on the right. The lNCUS and STAPES are a continuous opacity on the right. SEPTAL CARTILAGE, between lateral processes of VOMER INFERIOR CONCHA Bud of PERM. CUSPID Crypt of MOLAR 1 Lateral wall of ErHMorD Bud of MOLAR 2 VOMER ZYGOMATIC Pterygomaxillary fissure ‘mu’ (J Lateral process of PALATINE / ‘ Round foramen ALISPHENOID Sphenosquamosal suture ( I Site of basisphenoalisphenoidal yr (‘ Oval and spinous foramena m\\ yr ' suture S \ Apical whorl of cochlea ANNULUS “S d‘ MALLEUS Cupula of apical whorl of cochlea ~jl?““ INCUS and STAPES ”Vestibule i—J ’1 . I Apical whorl of cochlea I \ ’ I ateral semicircular canal Vestibule Posterior semicircular canal K I temal acoustic mcatus l u erior limb of posterior semicircular canal Figure 5.14 Tomogram 5.13 The MAXILLA is a triangular block containing the bud of DEClD. MOLAR 2 and its crypt and the margin of the crypt of MOLAR 1. It is fused with the ETHMOID except posteriorly, where the suture is still evident. Note the approximation of the MOLAR 2 crypt to the pterygoid t'ossa; the bony enclosure at this margin is incomplete. On the left. the lateral process of the PALATINE extends medialward to the lateral wing of the VOMER. at the top of the posterior choanae. This extension is interrupted on the right. The pterygo- maxillary fissure is evident on the left between the PALATINE and the MAXILLA; at this level. a small foramen penetrates to the nasal chamber. Drawing 5.1K The ALISPHENOID is sectioned near the round fora- men. The rostrum of the BASlSPHENOlD is penetrated by the bony canal about the tract of the embryonal craniopharyngcal pouch. In this specimen, the further course of this pouch through the BASISPHENOID is not well-demonstrated. and is omitted from the drawings. The bones of Bertin are transient in the fetus and infant. later fusing with the BASISPHEN- OlD. The carotid groove is well outlined between the BASISPHENOID and the PE’I‘ROSAL. The semicanal for the tensor tympani muscle indents the PETROSAL on each side. On the left is shown the slender hatnulus of the tensor tympani muscle, about which the tendon turns to descend to the MAL- LEUS. The footplate of the STAPES, the oval win- dow and adjacent extension of the vestibule are shown on the left. The whorls of the cochlea and the in- ferior curve of the posterior semicircular canal are shown on each side. The facial canal is well demar- cated. posterior to the tympanic cavity. The medial wall of the tympanie cavity contains the oval win- dow (shown on the left). the promontory. and the extension of the tympanic recess toward the round window. Its lateral wall is part of the SQUAMOSAL. Margin of bud of PERMANENT (‘usPID Ethmomaxillary suture Margin of crypt of MOLAR l MOLAR 2 Lateral portion of PALATINE Pterygomaxillary fissure Canal of vestige of craniopharyngeal tract. BASISPHENOID Round for-amen Site of basisphenoalisphenoidal suture Carotid groove Zygomatic portion of SQUAMOSAL \ Cupula of apical whorl of cochlea Petrosquamosal suture Nasal process INFERIOR (‘ONCHA Middle concha of ETHMOID ZYGOMATIC VOM1£R Bone of Benin ALISPHENOID Site of sphenooccipital synchond rosis Lingula Carotid groove , ' \ (Middle ‘ - , cranial fossa) BASIOCCIPITAL Cochlear-iform process MALLEUS lNCus ' Apical whorl _ MALLEUS ’ .. ‘~ ofcochlea \ Petrosquamosal suture 1;. ‘ ' V 1‘ ' lNcus Hamulus for the tensor tympani muscle in cochleariforrn process Footplate of STAPES Basal whorl of cochlea Semicanal for tensor tympani muscle Vestibule Ampulla of posterior semicircular canal Extension of tympanie cavity toward round window Facial canal fir , Posterior semicircular canal (Posterior cranial fossa) / '// -. , ,1. Mastoid fontanelle Figure 5.15 Crypt of MOLAR l Bud of MOLAR 2 Lateral process of PALATINE \ Rostrum of BASISPHENOID I ALISPHENOID I Round foramen u Sphenosquamosal suture \ ANNULus I MALLEUS .W a INCUS ) l Facial canal / ’ . / Vestibule / Posterior limb of posterior semicircular canal Apical whorl of cochlea lntemal acoustic meatus 86 The left MAXILLA contains the buds of the two DECIDUAL MOLARs. In the right MAXILLA, at a slightly superior level, the inferior portion of the maxillary sinus is seen. The lateral process of the PALATINE extends as a spur posteromedially from the combined mass of MAXILLA and ETHMOID. In this section. the alae of the VOMER are separated, on either side of the rostrum of the BASISPHENOID. The round foramen and the sphenosquamosal suture are shown in the ALlSPHENOlD on each side. The carotid groove is well distinguished beside the BASI— SPHENOID on each side. The superior portion of the internal acoustic meatus is outlined by the PETROSAL. This is separated from the lucency of the apical whorl of the cochlea. On the left. the vestibule is in continuity with the inferior limb of the posterior semicircular canal; on the right. the posterior portion of the posterior canal is sectioned at the posterolateral margin of the PETROSAL. and the superior limb of this canal is shown at its junction with the vestibule. The fossa of the endolymphatic sac lies between these two portions of the canal. On the left, the lateral semi- circular canal is in continuity with the vestibule. The hiatus of the facial canal is shown as an indentation on the anterior aspect of the PETROSAL on each side. The MALLEUS and the combined opacity of INCUS and STAPES are shown on each side. LACRIMAL INFERIOR CONCHA VOMER ‘ Margin of maxillary antrum ‘ I ‘ ‘ ZYGOMATIC Canal of vestige of ) craniopharyngeal tract. Carotid groove ANNULUS r f . / MALLEUS o 3 ’ Hiatus of facial canal a ‘ 9, ’ INCUS and STAPES YA" Vestibule ‘ ‘fl Lateral semicircular canal ‘_- Anterior limb of posterior ‘ \ semiCIrcular canal Posterior limb of posterior semicircular canal Endolymphatic duct Fossa of the endolymphatic sac / Apical whorl of cochlea lntemal acoustic meatus Figure 5.16 Tomogram 5.15 Semicanal of tensor tympani muscle for tendon of tensor tympani muscle Posterior limb of posterior semicircular canal Drawing At this level. the MAXILLA contains the superior margin of the bud oli MOLAR 2. The ethmomaxillary suture is more evident than in the sections inferior to this. The margin of the orifice of the infraorbital canal is shown on either side. The lateral process of the PALATINF. is shown on either side; it is approximated by the INFERIOR (‘ONCHA As the lateral wings (alae) of the VOMER are sec— tioned. they are shaped as prongs; the bones of Bertin Middle concha of ETHMOID Ethmomaxillary suture INFERIOR (,‘ONCHA Rostrum of BASISPHENOID Bone of Benin ALISPHENOID Sphenosquamosal suture Round foramen Lingula M . Groove of carotld artery ‘ , A ;'- Site of sphenooccipital synchondmsis—wfi Petrosquamosal suture MALLEUS lNcus Petrosquamosal suture Cochleariform process. Vestibule Lateral semicircular canal 2/ Mastoid fontanelle ETHMOID (Posterior cranial fossa) are in continuity with either wing. in approximation to the rostrum of the BASISPHENOID. Sutural demarcation of the lateral wall of the ETH- MOID from the MAXILLA is best shown at this transverse level. The lNFERlOR (‘ONCHA which is derived separ— ately from the ETHMOID. is shown in much of its length. Posterior and medial to it is the middle concha. The ALISPHENOID is sectioned in its vertical por- tion. at the level of the round foramen. Each ALI- SPHENOID is closely approximated to the BASI- SPHENOID at this level. This section of the PETROSAL on either side is through the vestibule. the basal whorl of the cochlea and the posterior semicircular canal. A margin of the basal and apical whorls is also shown on the left. The epitympanie recess of the tympanic cavity is enclosed by the PETROSAL and SOUAMOSAL. It contains the head of the MALLEUS and the body of the lNCUS. The base of the hamulus of the tensor tympani muscle is shown on the left. The fine bony laminae of the pyramid about the stapedius muscle are shown on the right. lnfraorbital groove Orbital process of MAXll.l.A MAXILLA Bud of MOLAR 2 Lateral process ol‘ PALATINE TEMPORAL. fossa BASISPHENOID SQUAMOSAL Superior margin of auditory canal Petrosquamosal suture Apical whorl of cochlea MALLEUS Vestibule Pyramidal eminence Canal of stapedius muscle Petrosquamosal suture Lateral semicircular canal Basal whorl of cochlea Mastoid ponion of PETROSAL 7/ , Posterior limb of posterior semicircular canal Zygomatic process of SQUAMOSAL Apex of pyramidal portion of PETROSAL Figure 5.17 The MAXILLA encloses the superior portion of the bud of MOLAR 2. the bud of PERMANENT MOLAR 1. and the inferior margin of the maxillary antrum. The orifice of the infraorbital canal and a portion of the canal are also shown. The ALlSPHENOlD is sectioned through the round foramen on the left. In the BASISPHENOID. the orifice of the residual bony tract about the embryonal craniopharyngcal pouch is shown as a discrete round luccncy. In the PE'l‘ROSAL. the cochlea is well distinguished on the left. The medial portion of the left internal acoustic meatus is indistinct. The vestibule and the adjacent portions of the semicircular canals appear as a large lucency in the PETRO— SAL. Only the verticle portion of the ANNULUS is well delineated on the left. The footplate of the STAPES is dis- tinct on the right. INFERIOR CONCHA Middle concha of ETHMOID VoMER lnfraorbital canal Lateral process of PALATINE 4 j Maxillary sinus Site of rostrum of BASISPHENOID ‘ zyooMAnc tract in BASISPHENOID ALISPHENOID Canal of vestige of craniopharyngeal , '\ Crypt of MOLAR 2 \ _3‘ A Round foramen / Site of sphenooccipital synchondrosis Lingula of BASISPHENOID ANNULUS ‘ . NNULUS MALLEUS - MALLEUS [Ncus ° lNcus A ‘\ Apical whorl of cochlea ’ ( g t‘ 351:," Hiatus of facial canal /' ‘ ‘n\ Footplate of STAPES in oval window ‘* Vestibule astoid antmm Vestibule Lateral semicircular canal Posterior limb of posterior semicircular canal Fossa for endolymphatic sac P‘sterior limb of anterior semicircular canal ommon limb of superior and posterior semrcnrcular canals Apical whorl of cochlea Figure 5.19 Tomogram Drawing This is the superior level of the tooth—containing part of the MAXILLA: the superior margin of the crypt of MOLAR 2 is shown on the left. On the lel't. the max- illary sinus is shown in continuity from the middle meatus through its penetration of the ETHMOID wall and into the MAXILLA. The inferior margin of the sinus is shown on the right. adjacent to the ethmomaxillary suture. The infraorbital canal is shown in full width on the right. and a portion ol~ its orilice is shown on the left. The lateral wall of the ETHMOlD is suturally de— marcated from the MAXlLLA anterior to the antrum. Fthmoconehal suture INFERIOR CONCHA Sinus of MAXILLA Ethmomaxillary suture VOMER Lateral process of PA] ATINL Rostrum of BASISPHENOID Bone of Benin BASISPHENOID Site of sphenooecipital synchondrosis Carotid groove BAsioccwrrAi Basal whorl of cochlea Margin of facial canal Pelrosquamosal suture ,. k . Mastoid foramen L, l V l lntemal acoustical mcatus Vestibule The INFERIOR CONCHA, which is separate from the ETHMOID in its derivation. joins it at a discrete suture. The VOMliR is again shown as a continuity of nar- row paramedian processes. each diverging lateralward toward the sides of the rostrum of the BASISPHIZ- NOlD. At this level. the BASISPHENOID and ALlSPHli- NOll) are well approximated. The ALlSPHENOlD is penetrated by the round foramen on the right. The tract about the vestige of the embryonal cranio— pharyngeal pouch is indistinct inside of the BASIS— Pl—lFNOlD and is omitted from the illustration. The superior lip of the BASIOCCIPITAL is slightly asymmetrical. giving erroneous impression of me— :hanical displacement. The PFTROSAI. is sectioned through the internal acoustic meatus. the vestibule. the cochlea and the posterior limb of the posterior semicircular canal. On the right. the facial canal is open on the anterior as— pect of the PETROSAL. On the left. the course of the canal medial to the tympanic cavity is shown. The epitympanic recess is smaller than in Figure 5.16 and is smoothly walled. It contains the head of the MALLEUS and the body of the INCUS. Middle concha of ETHMOID INFERIOR (‘oNcHA lnfraorbital canal MAXILLA Sinus of MAXILLA \ '\ ZYUOMATK‘ N . V‘. v' / \ f\\. \} ’7\s~. Base of crypt of MOLAR 2 . 'i . " Roundforamen (4/, /, \ ALISPHENOID \ t» +1 (i V > Lingula M Petrosquamosal suture Facial canal MALLEUS lNcus Petrosquamosal suture Posterior limb of posterior semicircular canal / Figure 5.18 Middle concha of ETHMOID Superior concha . -. Crypt of MOLAR 2 Site of rostrum of BASISPHENOID r Canal of vestige of hypophyseal tract Lingula i _ l At this level. the MAXILLA contains the superior margin of the crypt of MOLAR 2 and a larger portion of the maxillary antrum. A greater extent of the infraorbital canal is also shown. The wings of the VOMER are shown as narrow opacities on either side of the BASISPHENOID. The ALISPHENOID is sectioned through its vertical portion on each side. Within the BASISPHENOID‘ the interior of the rostrum an- terior to the tract about the embryonal craniopharyngeal pouch is irregularly luccnt. The vertical portion of the posterior semicircular canal is a discrete radioluccney bounded ventromedially by the shallow excavation of the cndolymphalic sac. The apical whorl of the cochlea is in focus near the anterolateral margin of the internal acoustic meatus. The hiatus of the facial canal is seen immed- iately lateral to the apical whorl of the cochlea on the right. The superior portion of the ANNULUS. the MALLEUS and the INCUS are distinct. Nasal process of MAXILLA h- v; w P'- lnfraorbital groove Sinus of MAXILLA J7 ZYGOMATIC V I VOMER Lateral process of PALATINE ALISPHENOID Sphenooccipital synchondrosis ANNULUS J /\ Carotid groove ‘ [\(\ “ M ' ALLEUS ANNULUS .4 MALLEUS 5/ h / A %? INcus lNcus ‘1’ ‘ ' ’ \ A' A 4 Vestibule Q Vestibule Lateral semicircular canal Posterior limb of posterior semicircular canal Apical whorl of cochlea 9O - teral semicircular canal J lntemal acoustic meatus ’ sterior limb of posterior semicircular canal Fossa for cndolymphatic sac / Hiatus of facial canal _/ Apical whorl of cochlea Figure 5.19 See legend on page 89. Tomogram Drawing Ethmoconchal suture Middle concha of ETHMOID INFERIOR CONCHA INFERIOR CONCHA Sinus of MAXILLA lnfraorbital canal Ethmomaxillary suture MAXILLA VOMER Sinus of MAXILLA Lateral process of PALATINE Rostrum of BASISPHENOID Bone of Benin Base of crypt of MOLAR 2 BASISPH ENOID Round foramen Site of sphenooccipital synchondrosis Carotid groove ALISPHENOID BASIOCCIPITAL . Lingula Basal whorl of cochlea Margin of facial canal Petrosquamosal suture Facial canal MALLEUS lNCUS Petrosquamosal suture Petrosquamosal suture lntemal acoustical meatus Vestibule I _ . ' ' x ' ' . n , . . \ Posterior limb of posterior semICIrcular canal Mastoud lommen / 91 Figure 5.20 The sinus occupies much of the central area of the MAXILLA. Lateral to this, the MAXILLA constitutes the floor of the orbit; the infraorbital groove is distinguised within it. This is the most superior radiographic level at which the lateral wings (alae) of the VOMER are distinguished. Radiographically. the eonchae appear composed of irregular bone. In contrast. the anatomical sections demonstrate only the simpler primary portions of the conchae. close to their bases. The ALlSl’HENOlD and BASISPHENOID are separated at the superior orbital fissure. The tract about the vestige of the embryonal craniopharyngeal pouch is small at this level. In the PliTROSAL. the apical whorl of the cochlea is distinct, The common limb of the posterior and anterior semicircular canals is inseparable from the posterior aspect of the sub- arcuate l'ossa on the left. The posterior limb of the posterior semicircular canal is distinct on the left. The MALLEUS and INCUS are distinct on the left. but are a fused opacity on the ri ght. LACRIMAL VOMER Nasolacrimal canal Rostrum of BASISPHENOID C9 . Infraorbital EFOOVC u l Maxillary sinus ZYGOMATIC Canal of vestige of hypophyseal ‘ tract D , J 9 Superior orbital fissure Site of sphenooccipital synchondrosis MALLEUS . ANNULUS ) l O ‘ C [NCUS r Anterior limb of anterior \ / ,. semicircular canal Apical whorl of cochlea lntemal 300115130 canal \ ‘ Mastoid antrum semicircular canals / Subarcuate fossa Posterior limb of anterior _ . . semicircular canal Posterior limb of posterior semicircular canal / Common limb of anterior and posterior Posterior limb of posterior semicircular canal Figure 5.21 Tomogram memg 5.21 The wall between the nasal chamber and the orbit is constituted of the MAXlLLA. lt contains the bud ol~ PERMANENT MOLAR 2. The nasolaerinial canal opens into the nasal cavity at this level, inferior to the li\'l4l:‘RlOR CONCHA. in this specimen. the ethmomaxillary suture is dis— eernable anterior to the nasolacrimal canal. Most of the complex details of the middle and su- perior conchae were lost in the anatomical preparation. 'i he superior tip of the lateral process of the PALA— TlNli is diseernable at the posterior extremity of the MAXILLA. INFERIOR CONCHA Middle Concha of ETHMOID VOMER Rostrum of BASISPHENOID Bone of Benin BASISPHENOID Carotid groove Hiatus at genu of facial nerve SUPRAOCCIPI’I’AL ( Posterior cranial fossa ) lntemal acoustic meatus The lateral wings of the VOMER are shown at their superior margins. The ALlSPHENOlD and BASlSl’HliNOlD are sepa— rated by the superior orbital fissure. In the Pl’i’l'ROSAl. on the left side. the internal acoustic meatus is sectioned obliquely. On the right side. the meatus approximates the vestibule. The full length of the lateral semicircular canals and the adja— cent parts of the vestibule are demonstrated on both sides. The prominence of the lateral canals indent the Cpl[_\‘l]lplmlC recesses. Also shown are the origin of the anterior limb of the anterior semicircular canal and the common crura ol' the anterior and posterior semicircular canals from the vestibule. and the vertical portion of the posterior semicircular canal. The tip of the apical whorl of the cochlea is shown on the left. The origin of the facial canal from the meatus is shown on the right. The hiatus of the canal. the site of the geniculate ganglion of the facial nerve. is shown on the left. The epit_\'mpanic recess of the tympanic cavity and the antrum are shown. On the lateral aspect of the antrum are small irregular penetrations into the SQUAMO- SAL: some of these appear as cells. Nasolacrimal canal INFERIOR CONCHA Sinus of MAXILLA ZYGOMATIC Bud of PERMANENT MOLAR 2 , Lateral process of PALATINE ALISPHENOII) Superior orbital fissure Canal of facial nerve Vestibule Anterior semicircular canal Cells in SQUAMOSAL Antrum Lateral semicircular canal Mastoid foramen Posterior semicircular canal Common, limb of anterior and posterior semicircular canals Figure 5.22 Middle concha of ETHMOID VOMER ALISPHENOID n Rostrum of BASISPHENOID Site of sphenooccipita] synchondrosis MALLEUS INCUS Anterior limb of anterior semicircular canal Posterior limb of anterior semicircular canal 94 'l‘he elements of the MAXlLLA at this level are highly similar to those. in Figure 5.20. 'l‘he medial portion of the ALlSl’HENOlD is essentially verti- cal and. hence. radiopaque. The ventral portion of the BASISPHENOID is conical in radiographic form. with irregular internal lueency. lts posterior portion is essentially square. Within the Pli'l'ROSAL. the anterior semicircular canal and the subarcuate l'ossa are in continuity. 'l‘he medial portion of the internal acoustic mcatus is sharply outlined. The epitym— panic recess of the tympanic cavity is well soon on each side. But the ossicles are indistinct on the left and not visualized on the right. NASAL LACRIMAL Nasolacrimal canal I, ' Sinus of MAXILLA ZYGOMATIC . K \ \ . Apex of pyramidal process of PETROSAL (Middle cranial fossa) O Apical whorl of cochlea Anterior limb of anterior 0 ‘f-‘fl semicircular canal v r. “ Epitympanic recess 1‘ G , I PALATINE Bone of Berlin Pctrosal process of BASlSPHENOID ; lntemal acoustic canal Subar'cuate fossa (Posterior cranial fossa) Superior limb of posterior semicircular canal Posterior semicircular canal Common limb of anterior and posterior semicircular canals Figure 5.23 Tomogram Drawing 5.22 — 523 l‘he nasal chamber and the orbit are separated by the E'I'HMOID, which is indented by the maxillary sinus and the nasolacrimal canal. The sinus and canal are continuous on the right; the nasolacrimal canal is a separately enclosed cavity on the left. The ALISPHENOID is a simple arch in section. The BASISPHENOID is block—like in its posterior portion and tapered anteriorly. lts apex is enclosed by the bones of Bertin and by tips of the wings of the VOMER. Maxillary sinus Nasolaerimal canal Nasolacrimal canal Middle concha of ETHMOID ZYGOMATIC (Orbit) MAXILLA Bone of Benin \ - _ \ VOMER " . . V/ i ‘ '. ' a , ;/ ALISPHENOID . . c, . -- ' /' — ‘x, \. Rostrum of BASISPHENOID // / ‘ , Superior orbital fissure .— t“ SQUAMOSAL Site of synchondrosis \" _ - EyI—‘V / Canal of facial nerve \ \ / 4, l (\ »~_ A » -. h,» r; / l ‘x , . / ‘ , . f VII ' ‘ lntemal acoustical mommy y Anterior limb of anterior semICIrcular canal BASISPHENOID Tip of lNcus Falcifomi crest Petrosquamosal suture in tegmcn Epitympanic recess Lateral semicircular canal Mastoid fontanelle EXOCCIPITAL Prominence of lateral \ki‘ ‘ semicircular canal in \V / lympanic cavity r/ .r» Vertical ponion of posterior semicircular canal 95 Figure 5.24 The orbital margin of the MAXILLA and the contour of the maxillary antrum within the fused E’l‘HMOlD and MAXILLA are highly similar to those in Figure 5.22. The nasolacrimal canal is located slightly more lateral than in Figure 5.23. and is further separated from the nasal chamber. This is the level of the posterior attachment of the middle eoncha. This attachment is broad, and its bone is irregularly opaque. 'l‘he ALlSPHENOlD and BASlSl’HENOlD are further sepa— rated by the superior orbital fissure. The anterior limb of the anterior semicircular canal is well demonstrated; the posterior limb is out of this plane. The tympanic cavity is sectioned through the epitympanie recess. LACRIMAL Nasolacrimal canal Cells of ETHMou) Sinus of MAXILLA Superior orbital fissure (Orbit) ALISPHENOID Rostrum of BASISPHENOID . . . Petrosal process of BASISPHENOID Site of sphenooccrpital synchondrosis (Middle cranial f0. Anterior limb of anterior _ _ semicircular canal Epitympamc recess Epitympanie recess \éfi? Internal acoustical meatus (Posterior cmnial fossa) Figure 5.25 Tomogram Drawing 5.24— 5-25 . , I N asolac rimal canal j (I Sinus of MAXILLA . ,7 l Middle cranial fossa / \z . , BAsispiiiaNom \ l ‘\ Anterior semicircular canal ) Base ot‘dorsum sellae The MAXlLLA and ETHMOJD are a single block. without suture distinction. The maxillary sinus is par- tially demarcated from the nasal chamber by the base of the middle concha. It is now separated from the orbit by a thin wall. The nasolacrimal canal is displaced lateralward. farther from the nasal Chamber, in comparison with Figure 5.24. The ethmoidal cells are distinguished in the posterior portion of this mass. The ALlSPHENOlD approximates the MALAR. The portion of the BASISPHENOID is immediately inferior to the liypopliyseal recess. In the PETROSAL at this level. the bony labyrinth is represented by the common limbs of the posterior and anterior semicircular canals. by the superior curve of the posterior semicircular canal and by the anterior limb of the anterior semicircular canal. This section is at the superiormost portion of the epitynipanic recess, lts medial aspect is smooth. But its lateral aspect is irregularly penetrated by cells of the SQUAMOSAL. MAXILLA Nasolacrimal canal Base of middle concha of ETHMOID ZYGOMATIC ALISPHENOID Superior orbital fissure ) SQUAMOSAL ‘- Petrosquamosal l . , suture ‘ Common limb of posterior and anterior semicircular canals /' Cells in mastoid portion Posterior limb of posterior of PETROSAL _ semicircular canal .) \ Petrosquamosal suture \ fl \ (Posterior cranial fossa) . . \ '/,l \ / Mastoid fontanelle \_ . / //.» ‘ r» - ./ Xi;— EXOCCI Pl rm. 97 Figure 5.26 The mass separating the nasal chambers and the orbit is probably of E’l‘HMOlD. The maxillary antrum extends nearly to the orbit. The nasolacrimal canal is skeletally enclosed. As is Figure 5.24. the conchae are irregular opacitics. 'l‘he BASISPHENOID is indented by the hypophyseal fossa. A lucency in the anterior wall of the fossa indicates the orifice of the tract about the embryonal hypophyseal pouch. The subarcuate fossa and the vertical portions of the anterior semicircular canals are distinct within the PETROSAL. The tympanic cavity is sectioned at the epitympanic recess. Nasal process of MAXILLA LACRIMAL Nasolacrimal canal \ g ,\ Optic foramen Sinus of MAXILLA \ Cells of ETHMOID dcfl V > ' ALISPHENOID ’ On'fice of tract about hypophyseal h‘ ‘ \ " pouch Rostrum of BASISPHENOID / HYPophyseal fossa (Middle cranial fossa) Anterior limb of anterior semicircular canal A Subarcuate fossa Epitympanic recess 13%? mm Superior orbital fissure Anterior limb of anterior semicircular canal Subarcuate fossa . . . Posterior limb of antcnor semicircular canal (Posterior cranial fossa) Posterior limb of anterior semicircular canal Apex of pyramidal portion of PETROSAL Figure 5.28 Tomogram Drawing 5.28 The base of the superior concha projects medialward from the E'l‘HMOlD. 'l’he nasolaerimal canal is open lateralward. 'l‘he dorsum sellae ol‘ the BASlSl’llENOlD is chon— dral. Hence. only the anterior wall of the hypophyseal l'ossa is demonstrated. 'l‘he optic l'oramen is enclosed by the superior root of the lesser wing, anteriorly, and by the inferior root. postcriorly. 'l‘he bony labyrinth within the PE'I‘ROSAL is repre— sented only by the anterior semicircular canal. In the fetus and infant this canal protrudes from the superior aspect of the PE’I‘ROSAL in the arcuate crest with the subarcuate fossa. containing dura. extending lateralward below it. The epit_\r'mpanie recess is now a cavity in the anterior part of the PETROSAL. The petrosquamosal suture is lateral to the epitympanie recess. N >. ‘ ‘ s1. )- ' / AsAi (In pusputive) l l ‘ LACRIMAL Nasal process of MAXII LA ' t l N )ldLllllldl (.dlld (/ ) dS( \ ,, Anterior root of lesser wing of SPHIiNOlD BAsIsvHIaNoID Site of hypophyseal fossa l i t t , < Anterior scmrcrrcular canal / Petrosquamosal suture Base ol‘superior conchaof E1 HMOIl) f\ ZYGOMA'I'IC C / " ALSIPHl-NOII) ' \ ‘ , Superiororhital fissure Posterior root ol~ lesser SQUAMOSAI SUPRAOCCIPITAI. 99 Figure 5.27 This section is through the superior margin of the maxillary sinus. The ethmoidal cells are now distinguishable in the pos- terior portion of the ETHMOID. The scroll pattern of the middle concha is shown. The nasolacrimal canal is enclosed by the LACRIMAL bone. The roots of the lesser wing are comparable to their appearance in Figure 5.24. The limbs of the anterior semicircular canal are distinct on the left. The internal acoustic canal is distinguishable on each side. The epitympanic recess and the mastoid antrum and adjacent cells are well shown on the right. Nasal process of MAXILLA . _ Superior root of lesser Wing LACRIMAL ' Nasolacrimal canal Optic foramen Sinus of MAXILLA Cells of ETHMOID ‘: O'/’/ (Orbit) T1 c V ZYGOMA Superior orbital fissure Rostrum of BASISPHENOID -\‘-~ -“ ALISPHENOID Inferior root of lesser wing (Middle cranial foss . . _ Anterior limb of anterior semicircular canal Epitympanic recess ’\ J W Antrum in mastoid portion of PETROSAL Posterior limb of anterior semicircular canal (Posterior cranial fossa) ‘\\ Hypophyseal fossa Epitympanic recess Antrum in mastoid portion of PETROSAL Anterior limb of anterior semicircular canal Subarcuate fossa Subarcuate fossa Posterior limb of anterior semicircular canal Figure 5.28 St‘t’ layout] on page 99. Tomogram 5.27— 5.26 Drawing 5.28 NASAL lin perspective) , f ' l Nasal rncess ofMAxuiA ' t l) 9 \¥‘ l Base of superior concha of ETHMmt) ! l LACRIMAI /‘ . Nasolacrimal canal k ) l \ \ / / \4] \I / ' (,2 ' Jl, Optic foramcn \ i /\ ZYGOMATIC . ' / I / I ALSIPHENOID C / , . v Superior orbital fiSsure ETHMOID K, ,4 (Orbit) Anterior root of lesser winv OfSl’Hl-NOID . E, Posterior root of lesser wing V " ‘ /» BASISPHLNOH) , ‘ y' ,- ' ' SQUAMOSAL \ I i ‘ < Anterior semicircular canal \ , ' W Epitympanic rccexs { ' \___\ , k , ,v . . ,. ,K \ ’9 (’ ' 71~Q\ 3).“: J g ' _ > , Subarcuute fussu ~ > ‘. Peti’osquammzil suture \ SUPRA()('('IPI [AL 101 Figure 5.29 The ETHMOlD opacity is narrow. The cthmoid cells are distinguishable in its posterior portion. The LACRIMAL encloses the nasolacrimal canal. in this and in the tomogram of Figure 5.30. the. processes of the lesser wing. enclosing the optic foreman. are distinct. The chiasmatic sulcus is distinct. Of the bony labyrinth within the PETROSAL, only the anterior semicircular canal is clearly shown. within the arcuatc eminence. , Nasal process of MAXILLA Nasolacnmal canal ' LACRIMAL Middle concha Cells in ETHMOID ZYGOMATIC Rostrum of BASISPHENOID Base of lesser wing of SPHENOID ALSIPHENOID \/ (Middle cranial fossa) Optic foramen Hypophyseal fossa Antrum in mastoid portion of PETROSAL Dorsurn sellae Anterior limb of anterior semicircular canal Antrum in mastoid Anterior semicircular canal . _ pomon 0f PETROSAL (Posterior cranial fossa) Superior portion of anterior semicircular canal Subancuate fossa Arcuate eminence Figure 5.30 Tomogram 5.30 5.29 The lateral wall of the ETHMOID is diminished, compared with the tomogram of Figure 5.29. The nasolacrimal canal is open lateralward. The crest of the anterior semicircular canal is the only structure clearly seen within the PETROSAL. N ASAL LACRIMAL Nasolacrimal canal Cells in ETHMOID « Zyoowmc Lesser wing Rostrum of BASISPHENOID _ Optic foramen ALISPHENOID (Middle cranial fossa) Chiasmatic sulcus Anterior clinoid process Hypophyseal fossa Antrum in mastoid portion of PETROSAL O in BASISPHENOID ‘30» m (Posterior cranial fossa) Anterior limb of anterior semicircular canal CHAPTER 6 105 Figure 6.1 Orientation of Sections 6.26 6.19 6.17 6.15 6.13 6.10 6I7' 6.4 6.2 é ‘. ‘1 ‘ 1 \ A a: f; 1,4 \_ ‘» '_, WM- ; a . ' .- 6741.-.- . 6.3 1 V \L “4‘“, L“ _H* 6.40 " . 6.5. 6.39 6.6 6.38 6181}. 6.9 1‘ 1‘ 6.36 r56.” ‘1 6.35 6.12 6-33 6.14 6.31 6.16 x , 6.29 6.18 6.27 _,..6:26 «4--.--.6.“ 2/ ‘ 6.21 6.23 DRAWING 107 Figure 6.2 Tomogram 6.2 a? lg 6.3 Drawing In this tomogram, matching anatomical Figure 7.3, the cancellous posterior portion of the PETROSAL appears relatively lucent. The tympanic cavity is less sharply marginned, and the tegmen appears irregularly thickened. The MALLEUS and lNCUS are dense masses, well demarcated from each other. lNcus Tegmen tympani Epitympanic recess Mastoid antrum r MALLEUS ) \ Mastoid air cell ANNULUS Facial canal Attachment of tympanic membrane 108 Figure 6.3 Tegmen Head of MALLEUS . \ v v ‘ \ Petrosquamosal articulation . ._ 3".“ :55}. . 3., ’ . ALISPHENOID ANNULUS SQUAMOSAL ANNULUS Tympanic cavity Short process of INCUS. in ineudal fossa This most lateral of the anatomical sections demonstrates an essentially uniform cancellous mass of the PETROSAL about the comparatively smoothly marginned mastoid portion of the tympanic cavity. The tegmen is thin. The petrosquamosal suture is seen at the anterior extent of the tympanic cavity. The SQUAMOSAL is sectioned through the medial portion of the mandibular joint. The ANNULUS is sectioned through its anterior and posterior portions. The head of the MALLEUS articulates with the body of the lNCUS. The short process of the lNCUS rests in the ineudal fossa. 109 Figure 6.4 Mastoid antrum Posterior limb, lateral semicircular canal Epitympanic recess \ /,/.o Tomogram 6.4 $21 mfl‘ K? 6.5 6.6 Drawing In this tomogram. the luccncy of the mastoid antrum is ex- tended into adjacent cancellous bone of the PETROSAL in- ferior to the antrum. The tomogram shows the posterior limb of the lateral semi— circular canal and a portion of the facial canal. Tegrnen tympani lNCUS MALLEUS Attachment of tympanic membrane Mastoid cells I - ANNULUS FaCIal canal llO Mastoid antrum Tegmen it PETROSAL ‘ ANNULUS lNCUS MALLEUS Epitympanic recess Prominence of lateral semicircular canal in tympanic cavity SQUAMOSAL Site of tensor tympani muscle ANNULus Gracile Process of MALLEUS Figure 6.5 The mastoid antrum of the tympanic cavity approxi- mates the cancellous superior—posterior portion of the PETROSAL. The petrosquamosal suture is at the anterior margin of the tegmen. The anterior portion of the ANNULUS is triangular in section. The posterior portion is grossly fused with Lateral semicircular canal the PETROSAL. The body of the MALLEUS closely approximates the long process of the INCUS. The slender gracile pro— cess of the MALLEUS is found in infants; it is usually not evident in tomograms. The chamber anterior to the MALLEUS is the site of the tensor tympani mus- cle. Petrosquamosal suture in tegmen ,/"',n ‘ ( 13%;4 ”1“" 1*; If 3. ' "n PETROSAL ANNULUS Long Process of INcus Semicanal of tensor tympani muscle ALISPHENOID SQUAMOSAL ANNULUS Handle of MALLEUS Figure 6.6 The lateral portion of the lateral semicircular canal is marginned by dense bone which is well distinguished from the adjacent cancellous bone of the PETROSAL. The petrosquamosal suture is within the tcgmen and its inferior margin protrudes as a ridge into the tympanic cavity. The semieanal of the tensor tympani muscle approximates the tegmen portion of the SQUAMOSAL. The ossicles are sectioned through the handle of the MALLEUS and the long process of the lNCUS. 111 Figure 6.7 Tomogram 6.7 l“ Wt 6.8 6.9 Drawing ln comparison with the anatomical section of Figure 6.6, this tomogram demonstrates the mastoid antrum and more of the facial canal. II also shows the MALLEUS and the larger por— tions of lNCUS and STAPES, anterior to the oval window. Mastoid antrum INCUS & STAPES Lateral semicircular canal MALLEUS Round Window \ \, Facial canal ANNULUS ANNULUS H ypotympanic recess Oval window Lateral semicircular canal PETROSAL r7 Facial canal ANNULUS Long Process of [NCUS Handle of MALLEUS Flgure 6.8 This anatomical section demonstrates the lateral semi— circular canal. the anterior limb of the anterior semi- circular canal and the distal portion of the facial canal. Note that the semicircular canals are distinctly mar- ginned by dense bone. The semicanal of the tensor tympani muscle approxi— Anterior semicircular canal Petrosquamosal suture (in tegmen) Semicanal of tensor tympani muscle ALISPHENOID SQUAMOSAL ANNULUS mates the pctrosquamosal suture. The posterior portion of the ANNULUS is incom— pletely fused with the PETROSAL The ossicles are sectioned at the handle of the MAL- LEUS and the long process of the lNCUS. Anterior semicircular canal Ampulla. lateral semicircular canal Posterior limb. lateral semicircular canal PETROSAL Facial canal Stylomastoid foramen ANNULUS Long process of [News Figure 6.9 The lateral semicircular canal is sectioned through its posterior limb and through its ampulla. The an— terior semicircular canal is sectioned through its an- terior portion. The hiatus of the facial canal is an indentation on the anterior superior face of the PETROSAL; this is the site of the geniculate ganglion. The distal portion of the facial canal is also shown, Hiatus of facial canal Petrosquamosal suture Semicanal of tensor tympani muscle SQUAMOSAL ANNULUS ALISPHENOID Handle of MALLEUS to the stylomastoid foramen. The semicanal of the tensor tympani muscle is adja- cent to the tegmen. The semicanal of the stapcdius muscle is shown in the posterior wall of the tympanic cavity. The ossicles are sectioned through the handle of the MALLEUS and the long process of the INCUS. 113 Figure 6 . 10 Tomogram 6.10 l I 6.11 6.12 Drawing This tomogram corrcsponds with the anatomical section of Figure 6.11. The subarcuate lost: is much more evident in this tomogram than in the anatomical section. Anterior limb, anterior Subarcuate fossa semicrrcular canal Anterior limb, lateral semicircular canal > Hiatus of facial canal Q‘ / Oval window Posterior limb, lateral O semicircular canal e %/ Facial canal / Site of STAPES & lNcus MALLEUS ANNULUS Round window Hypotympanic recess 114 Subarcuate fossa Ampulla, lateral semicircular canal Posterior limb, lateral semicircular canal PETROSAL M Facial canal Stylomastoid foramen Semicanal of stapedius muscle Lenticular process of New Figure 6.11 The lateral semicircular canal is sectioned through its posterior limb and ampulla and the anterior semi- circular canal through its anterior portion. The margin of the subarcuate fossa is shown. The lateral portion of the facial canal is in much of its length, from its approximation to the ampulla of the lateral semicircu- ANNULUS Subarcuate fossa Facial canal Posterior limb, lateral semicircular canal PETROSAL Semicanal of stapedius muscle Stylomastoid foramen ANNU LUS Pyramidal eminence semicircular canal Hiatus of facial canal Petrosquamosal suture Semicanal of tensor tympani muscle SQUAMOSAL ALISPHENOID ANNULUS Handle of MALLEUS lar canal to the Stylomastoid foramen. The semicanal of the tensor tympani muscle approxi- mates the tegmen. The semicanal of the stapedius muscle is partially sectioned in the posterior wall of the tympanic cavity. Anterior semicircular canal Hiatus of facial canal Petrosquamosal suture SQUAMOSAL ALISPHENOID ANNULUS Semicanal of tensor tympani muscle Handle of MALLEUS Lenticular process of INcus Figure 6.12 Section demonstrates the common limb and ampullae of the lateral and anterior semicircular canals, the posterior limb of the lateral canal and the superior portion of the anterior canal. The subarcuate fossa is larger than in Figure 6.1l. The facial canal is inferior to the common limbs; the medial margin of the hiatus of the canal and of the stylomastoid fora- men are also shown. The semicanal of the tensor tympani muscle is not well demarcated. The semicanal of the stapedius mus- cle is sectioned in a portion which is almost enclosed; also shown is the pyramidal eminence, around which the tendon of this muscle courses. The ossicles are sectioned at the handle of the MAL— LEUS and the Ienticular process of the INCUS. 115 Figure 6.13 Tomogram 6.13 l ‘6.14 Drawing 'l'hc subarcuatc l'ossa is prominent in this tomogram. It also shows the lateral limb of the posterior canal and the extent of the anterior limb of the anterior semicircular canal The round window is shown in thc tomogram but is out of view in the anatomical scction. Anterior limb, anterior semicircular canal Subarcuate fossa Ampulla; lateral semicircular canal Oval window Posterior semicircular canal Hypotympanic recess Posterior limb, lateral ‘ semicircular canal Round window ANNULUS Facial canal ll6 Figure 6.14 Semicanal of stapedius muscle Posterior limb, lateral semicircular canal PETROSAL Subarcuate fossa Anterior semicircular canal Facial canal Petrosquamosal suture \/ ANNULUS Pyramidal eminence Promontory Crura of Stapes with footplate ANNULUS in oval window This anatomical section is through the common limbs of the lateral and anterior semicircular canals, the posterior limb of the lateral canal and the superior portion of the anterior canal. Two portions of the irregularly contoured subarcuate fossa are exposed. A short potrion ol' the facial canal is shown adjacent to its hiatus. The semicanal of the tensor tympani muscle continues adjacent to the tegmen. In the specimen illustrated. the semicanal of the stapedius muscle penetrates the inferior aspect of thc PETRO— SAL; a thin bony wall is usual. The pyramidal eminence is see- tioned. There are irregular lacunae in the PETROSAL posterior to this semieanal; these are probably cells which will be air- containing. The basal whorl ol the cochlea protrudes as the promontory into the tympanic cavity. Superior to it is the oval window con— taining the footplate of the STAPES; the 2 crura of the STAPES are sectioned. ALISPHENOID Figure 6.15 The semicanals and the facial canal are shown in larger extent in this matching tomogram. It also demonstrates the fossa of the endolymphatic sac. Anterior semicircular canal Subarcuate fossa Posterior semicircular canal . Facral canal & Oval window f Mk Posterior limb, lateral semrcrrcular canal Semicanal of stapedius muscle Fossa of endolymphatic sac Petroexoccipital suture ll8 Tomogram 6.15 l 6.16 Drawing Figure 6.16 Superior semicircular canal Subarcuate fossa Posterior limb, lateral ' ' c rcanal . . semtcrr ula Foot plate of STAPES in oval wmdow Posterior semicircular canal Facial canal Hiatus of facial canal Semicanal of tensor tympani muscle Cells \ ' il :/ T ALISPHENOID Site of auditory canal Pyramidal eminence Semicanal of stapedius muscle ANNULUS . _ Hypotympanic recess Extensron of hypotympamc recess toward round window Promontory of basal whorl of cochlea This anatomical section is through the common limb of the lateral and anterior semicircular canals at its junction with the vestibule, through the superior portion of the anterior canal, the posterior limb of the lateral canal and the lateral potrion of the posterior canal. A large portion of the subarcuate fossa is also sectioned. The facial canal is shown at its hiatus. The semicanal of the tensor tympani muscle is partially en— closed. The semicanal of the stapedius muscle and its eminence are shown. The cells posterior to this semicanal are exception- ally large in this specimen. The oval window is shown superior to the promontory. The round window is out of sight in this anatomical section, above the extension of the hypotympamc recess. 119 Figure 6.17 The tomogram demonstrates a larger extent of the an- terior‘ posterior and lateral semicircular canals. It also shows the rcess of the endolymphatic sac and, less dis- tinctly. the cochlear duct. Superior semicircular canal Common limb, posterior & anterior Subarcuate fossa semicircular canals Common limb lateral & Posterior semicircular canal anterior semicircular canals Posterior limb, lateral Facial canal semicircular canal Recess of endolymphatic sac Oval window Cochlear canal 120 Tomogram 6.]7 6.18 Drawing Figure 6.18 Anterior semicircular canal, in arcuate eminence Subareuate fossa Vestibule Posterior limb, lateral Hiatus of facial canal semicircular canal Semicanal of tensor tympani muscle Posterior semicircular canal A f}! , . -, ‘ Site of auditory canal /I' . . ». "I ‘ ALISPHENOID /. Round window \, Semicanal of stapedius muscle ANNULUS Lateral pterygoid process Hypotympanic recess Extension of hypotympanic recess toward round window The labyrinth is sectioned through the vestibule. the posterior limb of the lateral semicircular canal and the lateral portion of the posterior canal. The superior portion of the anterior semi- circular canal is in the lip of the arcuate eminence. The round window is interposed between an extension of the hypotympanic recess and the vestibule. Open cells are distinguished posterior to the semicanal of the stapedius muscle and inferior to the posterior semicircular canal. In this section these cells extend to the inferior aspect of the PETROSAL. The facial canal is shown only at its hiatus. The medial margin of the semicanal of the stapedius is shown. The site of the auditory canal is indicated at its junction with the tympanic cavity and inferior to the semicanal of the tensor tympani muscle. 121 Figure 6.19 Tomogram 6.19 l iii/9W; 6.20 6.21 Drawing The corresponding tomogram shows the semicircular canals and the facial canal in greater extent. It also demonstrates the recess of the endolymphatic sac and the cochlea. which are out of the plane of this anatomical section. Anterior semicircular canal Common limb, anterior & posterior semicircular canals Subarcuate fossa g Facial canal Posterior semicircular canal Recess of endolymphatic sac Cochlea /‘l( g Posterior limb, lateral semrcrrcular canal and endolymphatic duct \ ANNULUS Petroexoccipital suture Hypotympanic recess Oval window 122 Anterior semicircular canal, in arcuate eminence \ \ Posterior semicircular canal Posterior limb, lateral semicircular canal Extension of vestibule _/ to round window “ Extension of hypotympanic recess to the round window H ypotympanic recess ANNULUS Figure 6.20 The labyrinth is anatomically sectioned through the vestibule, the junction of the posterior limb of the lateral semicircular canal with the vestibule, the supe— rior and inferior limbs of the posterior semicircular canal‘ and the superior portion of the anterior semi- circular canal. The latter is in the lip of the arcuatc eminence. Anterior semicircular canal, in arcuate eminence Posterior semicircular canal Recess of endolymphatic sac Posterior semicircular, canal Sigmoid groove EXOCCIPITAL Round window Basal whorl of cochlea Hypotympanic recess Figure 6.21 Section includes the vestibule, the basal whorl of the cochlea. and the superior portion of the anterior semi— circular canal. The superior and inferior limbs of the posterior semicircular canal are on either side of the endolymphatic sac recess. The round window is at the confluence of the vestibule and the basal whorl. The medial margin of the apical Subarcuate fossa Vestibule Facial canal Site of auditory canal ALISPHENOID Lateral pterygoid process The round window is shown in its relation to the vesti— bule and to an extension of the hypotympanic recess. The semicanal of the tensor tympani muscle is only slightly demarcated superior to the site of the muscu- lotubal canal. The ANNULUS is sectioned at its inferior portion. Subarcuate fossa Elliptical recess of vestibule Spherical recess of vestibule Facial canal Apical whorl of cochlea Spinous foramen Lateral pterygoid process Site of auditory canal Semicanal of tensor tympani muscle whorl is also in this plane. The semicanal of the tensor tympani muscle is demar- cated by a transverse ridge from the auditory canal and from the hypotympanic recess. The sigmoid groove separates the EXOCCIPITAL from the PETROSAL. Figure 6.22 In comparison with anatomical Figure 6.23. the tomo- gram further demonstrates the common limb of the an— terior and posterior semicircular canals. It also shows the recess of the endolymphatic sac extending into the area between the limbs of the posterior canal. Anterior semicircular canal Common limb, anterior & posterior Subarcuate fossa semicircular canals Posterior semicircular canal Facial canal Recess for endolymphatic sac ALISPHENOID fl/ WA Ampulla, posterior semicircular canal /\ Jugular fossa Cochlea Jugular process Vestibule & intemal Petroexoccipital suture acoustic meatus Tomogram 6.22 l 943$; 6.23 Drawing Figure 6.23 Elliptical recess of vestibule Subarcuate tossa Crest of vestibule Anterior semicircular canal.in S h _. l U f ”b l arcuate eminence p elica recesso vesti ue Posterior semicircular canal . Facral canal Recess of endolymphatic sac . . . Apical whorl of cochlea Posterior semtcrrcular canal Sigmoid oove Oval foramen t.» \“ EXOCCIPITAL ALISPHENOID Lateral pterygoid process Site of auditory canal Basal whorl of cochlea Semicanal of tensor tympani muscle H ypotympanic recess The. portions of the labyrinth expOsed in this anatomical section include the vestibule and the basal and apical whorls of the coch- lea. The superior portion of the anterior semicircular canal, in the arcuate eminence. And the superior and inferior limbs of the posterior semicircular canal; the inferior limb is close to its am- pulla. at its junction with the vestibule. The curved medial portion of the facial canal is sectioned in two places. superior to the cochlea. The area of the auditory canal lies between the PETROSAL and the ALISPHENOID encloses the oval foramen. 125 Figure 6.24 Tomogram 6.24 6.25 Drawing This tomogram, matching Figure 6.25, demonstrates a greater extent of the superior and posterior semicircular canals. It also demonstrates radiograpliic overlapping of the internal acoustical mcatus and vestibule. Anterior semicircular canal , , Subarcuate fossa Common limb. anterior & posterior semicircular canals . Internal acoustic meatus Posterior semicircular canal Recess for endolymphatic sac \\ f/ Ampulla, posterior semicircular canal % Jugular fossa \S Promontory Facial canal Falciform crest Cochlea \ ALISPHENOID Oval foramen Hypotympanic recess Site of auditory canal 126 Figure 6.25 Common limb, anterior& posterior semicircular canals Ampulla, posterior semicircular canal Sigmoid groove EXOCCIPITAL Vestibule . Facral canal Basal whorl of cochlea J ugular fossa Oval foramen Site of auditory canal Semicanal of tensor tympani muscle This anatomical section demonstrates the ampulla at the junc— tion of its inferior limb of the posterior semicircular canal with the vestibule, and the common limb of the posterior and ante— rior canals, at their junction with the vestibule. The cochlea is sectioned through its basal and apical whorls. The facial canal, superior to the vestibule, is of larger diameter than its more distal portions. The subarcuate fossa and the recess of the endolymphatie sac are shallow. The sigmoid groove separates the EXOCCIPITAL and the PETROSAL. The ALISPHENOID encloses the oval foramen. The lateral pterygoid process is sectioned in its greatest sagittal diameters. Apical whorl of cochlea ALISPHENOID Lateral pterygoid process 127 Figure 6.26 The tomogram additionally shows the junction of the internal acoustic meatus with the facial canal. And also the common limb of thc posterior and anterior semicircular canals; the latter is in the posterior portion of the arcuatc eminence. Subarcuate fossa Anterior semicircular canal lntemal acoustic meatus Common limb, anterior & posterior Facial canal semicircular canals Falciform crest Posterior semicircular canal ——P\ Cochlea /. xvi, a Ampulla, posterior semicircular canal Jugular fossa EXOCCIPITAL Oval foramen Site of auditory canal 128 To mogram 6.26 C Q l lififi: 6.27 Drawing Figure 6.27 Site of endolymphatic sac Falcifotm crest lntemal acoustic meatus Vestibule Apical whorl of cochlea Jugular fossa Lacerate foramen / . i “4/ ALISPHENOII) EXOCCIPITAL Carotid canal Site of auditory canal Basal whorl of cochlea In this anatomical section, the labyrinth is represented by the medial margin of the vestibule and by the basal and apical whorls of the cochlea. This is also the plane of the lateral extent of the internal acoustic meatus; the falciform crest intrudes from its anterior margin. The jugular fossa penetrates inl‘eriorly between the PERIOTlC and the EXOCCIPITAL, The carotid canal penetrates the PETROSAL from inferior, immediately posterior to the laceratetl foramen. 129 Figure 6.28 The tomogrzini corresponding to Figure 6.29 additionally dcmonstratcs rudiographic continuity of the internal acous— tic meatus and the cochlea. It also shows the posterior portion of thc nrcuzitc eminence. Subarcuate fossa Anterior semicircular canal lntemal acoustic meatus Recess for endolymphatic sac g Falcifonn crest Jugular fossa Cochlea Wat: 130 Tomogram 6.28 ,. k l? Wfiwfii 6.29 Drawing Figure 6.29 Falciform crest in internal acoustic meatus Apical whorl of cochlea Jugular fossa Lacerate foramen EXOCCIPITAL Site of auditory canal Basal whorl of cochlea Carotid canal This anatomical section demonstrates the basal and apical whorls of the cochlea, and the internal acoustic mcatus. The subarcuate fossa is shallow. The recess of the endolympha— tic sac is at its greatest depth. 131 Figure 6.30 In comparison with the anatomical Figure 6.3L the tomo- gram additionally demonstrates the posterior portion of the arcuate eminence. enclosing the superior semicircular canal, and a greater extent of the recess of the endolym- phatic sac. on the posterior face of PETROSAL. Subarcuate fossa Anterior semicircular canal - lntemal acoustic meatus Recess for endolymphatic sac \ J ugular fossa A) \b'\”\ Falcifonn crest Cochlea / \ Carotid canal EXOCCIPITAL Lacerate foramen Oval foramen ALISPHENOID Tomogram 6.30 ma {3; 6.31 Drawing Figure 6.31 F alciform crest Internal acoustic meatus Apical whorl of cochlea / ALISPHENOID EXOCCIPITAL Site of auditory canal Basal whorl of cochlea Carotid canal The basal and apical whorls of the cochlea approximate the internal acoustic meatus. The carotid canal and the anditory canal are adjacent, sepa- rated skeletally by processes of the ALISHENOID and the PETROSAL. 133 Figure 6.32 Tomogram 6.32 : Hi3??? 6.33 Drawing This tomogram is comparable to the anatomical scction of Figurc 6.33. The l'alciform crcst is wcll distinguished in the internal acoustic mcatus. Thc antcrior enclosure of the carotid canal by the PETROSAL and thc ALIS— PHENOID is indistinct. lntemal acoustic meatus Falciform crest Jugular fossa Basal whorl of cochlea Oval foramen ALISPHENOID Carotid canal EXOCCIPITAL Figure 6.33 lntemal acoustic meatus Basal whorl of cochlea Round foramen Jugular fossa ~— ALlSPHENOlD EXOCCIPITAL Site of auditory canal Carotid canal The cochlea is represented only by its basal whorl, which is separated by a thin plate from the internal acoustic meatus. The ALlSPHENOlD joins the PETROSAL at suture, superior to the site of the auditory canal. The round foramen penetrates the ALlSPHENOlD in posteroanterior direction. 135 Figure 6.34 This iomogram corresponds closely with the anatomy of Figure 6.35. Internal acoustic meatus Carotid canal 1v \_\\\ é ALISPHENOID EXOCCIPITAL I36 Tomogram 6.34 E Hfififi i , 6.35 Drawing Figure 6.35 Basal whorl of cochlea internal acoustic meatus Carotid canal Spinous foramen Jugular fossa EXOCCIPITAL ALISPHENOID The internal acoustic canal opens in the posterior face of the PETROSAL. The medial portion of the basal whorl is sepa- rated from the mcatus by a thick layer of dense bone. The carotid canal is partially cncloscd infcriorly. 137 _ Basal whorl of cochlea lntemal acoustic meatus Carotid canal Jugular fossa Round foramen ExoccmTAL ALISPHENOID Figure 6.36 The basal whorl of the cochlea is a shallow depression in this section. Only the outer portion of the internal acoustic is seen. The carotid canal is enclosed between the PETROSAL and the ALISPHENOID. The pos- terior portion of the round foramen is seen in the ALlSPHENOlD. Margin of basal whorl of cochlea Carotid canal ALISPHENOID EXOCCIPITAL F1gure 6.37 The margin of the basal whorl is discernable in the PETROSAL. The internal acoustic meatus is an angular indentation upon its posterior face. The carotid canal is enclosed by the PETROSAL except on its lateral aspect. 138 6.36 ‘ 6.37' 6.38 6.39 Drawing PETROSAL Carotid canal ALISPHENOID Superior process EXOCCIPITAL Margin of hypoglossal canal Inferior process Figure 6.38 The PETROSAL is sectioned in its pyramidal portion. The bone is almost uniformly can— cellous. The medial margin of the jugular fossa is in View. The adjacent portion of the EXOCCIPI- TAL is divided into a superior and inferior process. with the margin of the hypoglossal canal between them. The carotid canal indents the anterior margin of the PETROSAL. PETROSAL Carotid canal Condyloid canal M“ ALISPHENOID Ocelpital condyle H ypoglossal canal Figure 6.39 The superior and inferior processes of the EXOCClPlTAL are distinguished by the hypo- glossal canal. The occipital condyle is a distinct protrusion upon the inferior aspect of the inferior process. The carotid indents the PETROSAL less than in Figure 6.38. 139 Figure 6.40 6.40 6.4l Drawing PETROSAL Hypoglossal canal Carotid canal Condyloid canal ALISPHENOID BASISPHENOID Exocc l PITA L This is the apex of the pyramidal portion of PETROSAL. The variable condyloid canal is well shown in the EXOC— CIPITAL. 140 Figure 6.41 BASISPHENOID Synchondrosis ALISPHENOID EXOCCIPITAL BASIOCCIPITAL Foramen magnum The BASISPHENOID and BASIOCCIPITAL are the median masses of the busieranium. The margin of the forumen magnum is seen between tthe BASIOCCIPITAL and the EXOCCIPI- TAL. 141 Selected Bibliography Anatomy of the Cranium, Human Fetus and Infant Bosma, J. F. (Ed.) Symposium on Dmtelopment of the Basi— cranium, Washington. Government Printing Ollicc,l977. Avail- able from Superintendent of Documents as #017—047—0001 1—6. Crelin, E. 5.: Anatomy of the Newborn: An, Atlas, Philadelphia, Lea & Febiger, 1969. Elias, H.: Basic Human Anatomy as Seen in the Fetus, St. Louis, Green, 1971. Nafiagas, J. C.: A comparison of the growth of the body dimen— sions of anencephalic human fetuses with normal fetal growth as determined by graphic analysis and empirical formulae, Am. J. Anat., 35:455—494, 1925. Parke, W. W.: Photographic Atlas of Fetal Anatomy, Balti- more, University Park Press, 1974. Radiograhy of the Cranium, Human Fetus and Infant Berkvens, Th.: Radiography of the fetal skull, Acta. Radiol, 342250—252, 1950. Caffey. J.: Pediatric X—Ray Diagnosis, 6th Edit. Chicago, Medi- cal Publishers, 1973. Chasler, C. N.: Atlas of Roentgen Anatomy of the Newborn and Infant Skull, St. Louis, Green, 1972. Krogman, W. M. and Chung. D.: The craniofacial skelton at the age of one month, The Angle Orthodontist, 35: 305—310, 1965. Tomography and Other Techniques of Sectional Radiography Gordon, R., Herman, G. T. and Johnson, S. A.: Image recon- struction from projections. Scientific American, 233:56—68, 1975. Ledley, R. S.. DiChiro. G., Lucsscnhop, A. J. and Twigg. H. L.: Computerized transaxial x—ray tomography of the human body, Science, 186: 210—215, 1974. NCW. P. J. F. and Scott, W. R.: Computed Tomography of the Brain and Orbit (EMI Scanning), Baltimore, Williams and Wilkins, 1975. Prewitt. J.: Prospective methodological advances in radiologic demonstration of the hasicranium, In Bosma, J. F. (Ed.) Sym- posimn on Development of Basicranium, Washington, Gov— ernment Printing Office. 1977. Available from Superintendent of Documents as #017—047—0001 1—6. Robinson, A. L.: Image Reconstruction (II): Computerized Scanner Explosion, Science, 190:647 and 710, 1975. 1975. Webbcr. R. L.: Prospective methodological advances in radi- ologic demonstration of the basicranium, In Bosma, J. F. (Ed.) .S'ymposiam on Development of the Basicranium, Washington, Government Printing Office, 1977. Tomography of the Cranium, Human Adult Berrctt, A. Brunner. S. and Valvassori. G. E. Modern Thin- Section 'I’omography, Springfield, Thomas, 1973. Binet E. F., and Moro. J. J.: A tomographic study of the base of the skull, Med. Radiog. and Photog, 48:30—35, 1972. Brunner. S.. Petersen. O. and Stoksted, P.: Laminagraphy of the temporal bone. Am. J. Roentgenol. 86:281—291. 1961. Davcs, M. L. and Loechel. E.: The Interpretation of Tonto- grams of the Head, An Atlas, Springfield. Thomas, 1962. Etter, L. E.: Atlas of Roentgen Anatomy of the Skull, Spring- field. Thomas, 1970. Fischgold, H., David, M. and Bregeat, P.: La Tomographie de la Base Du Crane En Nearo—Chirargie et Neuro-Opthalmologie, Paris, Masson, 1952. Jensen. J. and Rovsing, H.; (Ed’s) Fundamentals of Ear Tomograp/t_\', Springfield. Thomas, 1971. Francois, J. and Barrois, J. J.: Anatomic tomographique de l’os temporal normal. Annales de radiologie, 2:71—98, I959. Holvey. E. H., Rosenthal. L. M. and Anson. B. J.: Tomography of the skull. Radiology. 44:425—448. 1945. Potter. G. D.: Sectional Anatomy and Tomography of the Head, New York, Grune & Stratton, 1971. 143 Valvassori. (i. and Buckingham. R. /\.: 'l‘omography and Cross Sections of the Ear. Philadelphia. Saunders. 1974. Valvassori. (i. E. and Pierce. R. H.: The normal internal audi— tory canal. Am. J. of Rm'nllqcnolq 92:1232. 1974. Tomography of the Cranium, Human Infant and Child Altmann. Ii: (‘ongenital atresia of the ear in man and animals. Ann. ()I()/.. R/Iin, am/ Luring. 64:824—858. l955. Brunner. 8.: Radiological examination of temporal bone in infants and children. Radio/0g); 82:401—406. 1964. Jensen. 1.: Malformation ol' the inner ear in deaf children. Acm Rm/iol. (Stockh. ). Suppl: 286: 1 1—95; 1969. Jensen. .l. and Rovsing. ll.: 'l‘omography in congenital malfor— mation of the middle ear. Radiology 90:268—275. 1968. Naunton. R. F. and \i’alvassori. (i. E: lnner ear anomalies: their association with atresia. I.tlrj\';1gtm'npr‘, 7X: l()4l~~l(), 1968. I44 Anatomical Index The bones which are separate in the term infant are listed in the composite within which they will be united during postnatal development. Thus. the BASIOC- (Z‘IPITAL. EXOCCII’ITAL and SUPRAOCCIPITAL are listed in the OCCIPI- TAL composite. The BASISPHENOID. ALISPHENOID and PTERGYC‘OID in the SPHENOID composite. The NASAL SEPTUM and INFERIOR CONCHA in the ETHMO") composite. The PETROSAL. SQUAMOSAL and ANNULUS in the TEMPORAL composite. The. MALLEUS. INCUS and STAPES are listed as OSSICLES. Chapters 3 4 5 ALISPHENOID (see SPHENOID composite) ANNULUS (see TEMPORAL composite BASIOCCIPITAL (see OCCIPITAL composite BASISPHENOID (see SPHENOID composite CONCHA, INFERIOR (see ETHMOID composite) ETHMOID composite ETHMOID Cells 4.l()—.l3 524—30 Concha, middle 3.1 4.9—.15 5.12—.29 Concha, superior 4.12—.15 5.18#.28 Cribriform plate 3.3 4.8—.15 Crista galli 3.3 4.9—.15 Ethmomaxillary suture 5.12—.19 CONCHA, INFERIOR 3.1 4.9—.15 5.14—.2l SEPTAL CARTILAGE 3.1 4.7—. 19 5 11—.13 EXOCCIPITAL (see OCCIPITAL composite) FRONTAL 3.1—.3 4.7—.16 Mctopic suture 3.1 4.6—.7 Supraorhital I'oramen 3.1 Zygomaticofrontal suture 3.1 4.13 INCUS (see OSSICLES) INFERIOR (‘ONCHA (see (‘ONCHA. INFERIOR IN ETHMOID composite) LACRIMAL 3.1. .2 4.9 SIS—.31 MALAR 3.1. .2. .4 5.16 146 MALLEUS (see OSSlCLES) MAXILLA Alveolar process 3.1, 2, 4, CUSPID, DECIDUAL and crypt CUSPID, PERMANENT and crypt lNClSOR, LATERAL, DECIDUAL and crypt lNClSOR, LATERAL, PERMANENT and crypt lNClSOR, MEDlAL, DECIDUAL and crypt lNClSOR, MEDIAL, PERMANENT and crypt lnfraorbital canal, notch 3.1 MOLAR l, DECIDUAL and crypt MOLAR l, PERMANENT and crypt MOLAR 2, DECIDUAL and crypt Nasal process 3.1 Nasal spine, anterior 3.1—.4 Nasolacrimal canal Palatine l'oramen, anterior 3.4 Palatine process 3.4 Orbital process Premaxillomaxillary suture, site of Pterygomaxillary fissure Sinus NASAL 3. 1—. 3 OCCIPITAL composite BASISPHENOID “Basion”, site of 3.3—.4 Condyle 3.2, .4 Notochord, vestige, site of Sphenooccipital synchondrosis 3.3—.4 EXOCClPlTAI. Condylc 3.2, .4 Condyloid canal 3.4 Foramen magnum 3.3—.4 Hypoglossal canal 3.3—.4 Inferior process 3.4 Jugular fossa 3.4 .lugular process 3.4 Mastoid fontanelle. 3.2—.4 Sigmoid groove 3.4 Superior process 3.3 SUPRAOCCIPITAL 3.2—.4 OSSICLES lNCUS MALLEUS 3.4 STAPES PALATINE Lateral process Nasal spine, posterior 3.4 Chapters 4.7—.11 4.8—.9 4.9 4.8—.9 4.8 4.1()—.l3 4.ll—_l3 4.10—.ll 4.10-.15 4.6—.ll 4.9 4.9 4.8—.15 4.10—. 13 4.6—.7 4.37 4.37—.39 4.23 4.43—.47 4.39—.51 4.36—.48 4.32—.49 4.43—.46 4.30—.42 4.24—.37 4.37—.39 5 5.6—.9 5.9—.12 5.8—.14 5.8—.10 5.8—.12 5.8—.11 5.9—.11 5.11—.20 5.8—.15 5.21 5.8-.19 5.14—.29 5.9—. 11 5.20—.30 5.6 5.6—.9 5.16 5.6 5.8—.14 5.15—.28 5.21—.30 5.6—.10 5.9—.10 5.6—.22 5.5—.8 5.6—.9 5.6—. 10 5.6—.9 5.7—. l 2 5.7 5.8—.23 5.6—.28 5.7—.23 5.7—.22 5.10—.17 5.9—.21 5.8 6.39 6.39—.40 6.41 6.38—.40 6.38 6.24—.37 6.25 6.40 6.2—.12 6.2—.12 6.7—.16 Chapters 3 4 5 6 Palatine foramcn. posterior 3.4 Medial process 3.4 4.14—. 15 5.6—. 10 PARlETAL 3.1—.4 4.18—.51 PETROSAL (see TEMPORAL composite) PTERYGOID (see SPHENOID composite) SEPTAL CARTILAGE (see ETl-lMOlD composite) SPHENOID composite ALlSPHENOlD 3.2—.4 4.16—26 5.9—.30 6.23 Lacerate foramen 3. 5.l()—.l 1 6.27—.30 Orbital fissure. inferior 5.11—.12 Orbital fissure. superior 3.3 4.l()—.l9 5.2()—.28 Oval foramcn 3.3—.4 4.22—.23 5.1 l—.13 6.23—.32 Round foramen 4.16—.18 5.9—.19 633—36 Sigmoid groove 3.4 6.2l—.23 Splicnosquamosal suture 3.2 5.l()—.l6 Spinous foramcn 3.3—.4 5.9——.l3 6.35 Pterygoid process. lateral 3.4 4.16—.2l 5.7—.9 6.18—25 BASISPHENOID Basisphcnoalisphenoidal suture 3.3-.4 4.17—.23 5.13—.l4 Bones of Berlin 5.14—.23 Carotid groove 3.3—.4 4.22—.23 5.14—.2O Chiasmalic sulcus 3.3 4.18 5.30 (‘linoid process. anterior 3.3 4.2()—.2l 5.30 Craniopharyngeal tract, vestige of 418—21 5.14—.26 Dorsum sellae 3.3 5.25—.29 Hypophyscal fossa 3.3 5.28—.3O Lesser wing 3.3 4.16—. 19 5.27—.30 Lingula 5.14—.l9 Optic canal 3.1 4.16—.l() 5.26—.3() Ptcrygoid l'oramen 4.19 Ptcrygoid process. medial 3.4 4.16—.l8 5.6—.11 Ptcrygomaxillary fissure 5.8—.10 Ptcrygopalatine suturc. 5.8 Rostrum 4.16 5.15—.29 Sphenooccipital synchondrosis 3.3—.4 4.23 5.6—.22 PTERYGOID 3.3 418—.1‘) 5.8—.12 SQUAMOSAL (see TEMPORAL composite) STAPES (see OSSlCLES) SUPRAOCClPlTAL (see OCClPlTAL composite) TEMPORAL composite ANNULUS (Tympanic ring) 3.2. .4 425—39 5.6—.21 6.2—.20 'l‘ympanum. site of 3.2. .4 425—39 5.7—.9 6.2-.4 PETROSAL Acoustic meatus. internal 3.3 430—.42 513—24 622—35 Falciform crest 430—37 5.23 6.24—.32 Apex 3.4 424—26 516—26 638—40 Apical whorl (see Cochlca) Arcuate eminence 3.3 4.38—.44 528—30 6.18—23 Auditory tube. or canal, site of 5.7—.12 6.16—.32 Basal whorl (see Cochlca) Carotid canal 3.4 4.25 5.7—.19 6.27—.40 Cochlea 147 148 Apical whorl Basal whorl Cochlear canal Cochlcariform process Endolymphatic duct Endolymphatic sac. recess of Eustachian tube (see Auditory tube) Facial canal Facial canal. hiatus Facial canal, stylomastoid foramcn Mastoid process Oval window Pctrooccipital suture Petrosquamosal suture Promontory over basal whorl of cochlea Pyramidal eminence Round window Scmicanal of stapedius m. Semicanal of tensor tympani m. Scmicircular canals Anterior and posterior, common limb Anterior Lateral Posterior Styloid process Stylomastoid foramen (sec facial canal) Subarcuate fossa Superior orbital lissure (sec Orbital fissure, superior) Tegmcn tympani Tcmporooccipital suture (see petrooccipital suture) Tympanic cavity Antrum Epitympanic recess Hypotympanic recess Vestibule Whorl, apical (see Cochlea) Whorl. basal (see Cochlca) SQUAMOSAL Cells Mastoid fontanelle (sec OCClPITAL. Mastoid fontanelle) Squamoparietal suture Sphcnosquamosal suture Temporomandibular articulation 3 Tympanic cavity (see 3.2, .4 3.4 3.3 3.3 Li) R») #IQ .l—. .l—. .4 PETROSAL. Tympanic cavity) Zygomatic process 3.2. .4 VOMER ZYGOMATIC 3.4 3.|—.2. .4 U.C. BERKELEY LIBRARIES CDE‘IL‘IBES‘l Chapters 4 4.26—.3l 4.26—.37 4.48—.51 4.26—.42 4.34 4.24—.5l 4.25—.5l 432—.37 4.43 4.24—41 4.3()—.47 4.34—.36 4.36—.51 4.38—.49 4.24 4.46—.51 4.25—39 4.25—.47 4.22—.48 436—37 423—51 422—23 4.16—.23 4.7—.16 4.10~.15 5 5.10—.22 5.9—.19 5.1] 5.14—.16 5.15 5.9—.18 5.10—.23 5.14—.21 5.7 5.16 5.8—.I0 5.7—.16 5.11—28 5.1 1—.12 5.16 5.9 5.16 5.9—.l6 5.17—.25 5.2()—.3() 5.l3—.2l 5.13—.25 5.7—.9 520—229 5 21—.27 5.14 5.20—.3() 5.22—.28 5.7—.11 58—21 5.21 5.1()—.16 5.9—.16 6.9—.20 5.8~.24 6 621—31 6.21—.37 6.17 6.19 615—.30 6.2—.26 5.9—. l 8 6.9—.12 6.7—.l9 6.15—.l9 6.3—. 14 6.14—. l 6 6.12—.l6 6.7—.21 6.1 1—.18 6.5—.25 6.17—.26 6.8—.30 6.4—.20 6.13—.26 6.10—.3() 6.2—.8 6.3 6.2—.7 6.2—.5 6.7—.24 6.18—.26 U 8. GOVERNMENT PRINTING OFFICE: 1977 Ow214—631