THE 
 
 ANATOMY AND PHYSIOLOGY OF EXPRESSION, 
 
 % 
 
 V A.ND THE 
 
 HUMAN TEETH 
 
 IN THEIR 
 
 /■ 
 
 RELATIONS TO MASTICATION, SPEECH, AND APPEARANCE 
 
 
 BY 
 
 J. H. McQUILLEJSr, D. D. S., 
 
 •b- 
 
 PROFESSOR OF ANATOMY, PHYSIOLOGY, AND HYGIENE IN THE PHILADELPHIA DENTAL COLLEGE. 
 
 PHILADELPHIA: 
 
 J. B. LIPPINCOTT & CO. 
 1864 . 
 
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J 
 
 PREFACE. 
 
 The accompanying Addresses may be said to have had their origin 
 in a communication published by me in the Dental Cosmos, in connec¬ 
 tion with an extract from an article by Prof. Oliver Wendell Holmes, on 
 ‘*The Doings of the Sunbeam,” presented in the Atlantic Monthly. 
 My remarks were as follows:— 
 
 “ When it is remembered that within the few square inches comprised 
 by the human face, room is found not only for traits of all of one’s ances¬ 
 tors, but also that the cares and anxieties, the'joys and sorrows, the hopes 
 and fears, and the moral, mental, and social associations and trainings of 
 the past of a person, leave ineffacable traces, which are perceptible to the 
 most obtuse, if they will exercise their perceptive faculties, and which 
 enable the keen and philosophical observer to form a fair estimate of the 
 past experience and present and future capabilities of the individual, it is 
 not a matter of surprise that Lavater, and others, who have made the 
 human face a special object of study, should have been so enthusiastic 
 with regard to it. Moore, it is true, has said— 
 
 ^“In vain we dwell on lines and crosses, 
 
 Crooked mouths, or short proboscis: 
 
 Boobies have looked as wise and bright 
 As Plato, or the Stagyrite; 
 
 And many a sage and learned skull 
 
 Has peeped through windows dark and dull.’ 
 
 While this is undoubtedly true in exceptional cases, there is more of 
 poetic imagination than actual truth in a broad application of such as¬ 
 sertions ; for there is almost invariably associated with high moral and 
 mental manifestations, or the reverse, an unmistakable evidence of the 
 fact on the brow of the person. It may not be evident at a first and 
 superficial glance, or when the features are in repose; but the spirit 
 
 2 (iii) 
 
4 
 
 which brings the muscles of expression into action speaks through them 
 in a language not easy to be mistaken. 
 
 “All persons, from the lisping babe to the hoary patriarch, are more or 
 less physiognomists; in other words, are attracted or repelled by the 
 expressions of the face. With the many, the impressions formed are in¬ 
 stinctive and emotional in their character, rather than the results of calm 
 and philosophical reasoning. The opinions arrived at under the former 
 conditions of mind, as a general thing, are not very reliable, and are 
 apt to be abandoned as quickly as they were adopted, and are quite as 
 unimportant in their results as hasty conceptions generally are; but 
 those whose duties bring them in contact with large numbers of their 
 fellow-beings must, of necessity, depend in a great measure on the phy¬ 
 siognomy for an estimate of the character and capacities of those who 
 come before them as strangers for a brief period only; and while it would 
 not do to rely implicitly and irrevocably on such data, a person of large 
 experience, possessed of fair perceptive and reasoning faculties, is not 
 likely to be led far astray in his conclusions. 
 
 “ It is not merely as a means of forming an estimate of character that 
 the face becomes an interesting and important object of study. To the 
 artist, whether as a sculptor or a painter, who aims to excel as a deli¬ 
 neator of nature, it recommends itself with peculiar force. Every one’s 
 attention is liable to be attracted by strongly-marked and characteristic 
 features. A high and expanded forehead, a prominent nose, and dark 
 and expressive eye, or a mouth indicating firmness of purpose, are not 
 likely to escape observation and comment; but to perceive and retain in 
 the memory those fine shades of difference which exist between the mass 
 of faces, (that are so much alike, and yet so dissimilar,) and delineate them 
 in marble or on canvas so perfectly that there can be no question as to 
 the resemblance, requires peculiar natural gifts, combined with long-con¬ 
 tinued and careful study of the face during life, when by the action of 
 the muscles of expression it is constantly undergoing a thousand and 
 one changes, and by frequent dissections of the cadaver to ascertain the 
 size, shape, origin, and insertion, and the relations which these muscles 
 bear to one another and the surrounding parts. 
 
 “ To no one, however, does the study of the human face, in its various 
 forms and aspects, recommend itself with more force than to the dental 
 
5 
 
 practitioner; for, called upon as he is, not only to relieve suffering hu¬ 
 manity from the greatest pain to which flesh is heir, but also to repair the 
 ravages of decay, either in efforts directed toward the preservation of the 
 natural organs, or, when these are lost, to supply artificial substitutes, if 
 he is not as quick to perceive and as able to retain in his memory the 
 nice shades of expression of the same face, and the characteristic points 
 of resemblance or difference between various individuals as the sculptor 
 or painter, he will fail in many essential particulars to meet all the just 
 and proper demands upon him. 
 
 '‘A practitioner always on the watch, and quick to perceive the slight¬ 
 est change of expression in the face of his patients when operating in the 
 neighborhood of an exposed pulp, or in administering an anaesthetic, will 
 be much less likely to give unnecessary pain, or bring life in jeopardy, 
 than those who are indifferent in regard to such matters. Again, it is 
 not reasonable to suppose that a symmetrical and natural appearance can 
 be given to teeth much broken up by decay, when the effort to file or fill 
 them is intrusted to one who has not paid due attention to the form, 
 position, and relations of the dental organs in their normal condition; or 
 that such a one can arrange and insert artificial substitutes with any 
 certainty that they will preserve or restore the old and familiar expres¬ 
 sions of the face, so well remembered and possibly admired by friends and 
 acquaintances. Opportunities, indeed, are sometimes offered, requiring 
 little or no effort to improve the appearance by the introduction of arti¬ 
 ficial teeth; but to accurately meet the varied complexions and forms of 
 face which present themselves, so that the results shall prove faultless in 
 their adaptation, is deserving of the highest meed of gratitude and praise 
 on the part of the patients. 
 
 “As the most careful observers and the best judges of what constitutes 
 a natural expression, can only form an approximate estimate of the ex¬ 
 pression of those whom they are called on to serve after the loss of natu¬ 
 ral teeth, it is reasonable to infer that valuable assistance would be found 
 by bringing in the aid of photography to determine nice or doubtful 
 points under such circumstances. Indeed, as the memory of man is so 
 treacherous, it would be of assistance even in cases where the face is long 
 and well known to the operator. At a period when photographs are so 
 much in vogue that they are used as ^'cartes de visile ,and when it is the 
 
6 
 
 exception where persons have not sat for their picture, the dentist will 
 have little or no difficulty in securing full-face, quarter-face, and profile 
 views of patients taken long before the loss of the'teeth. With these in 
 hand, the skillful and artistic practitioner will be able to preserve or re¬ 
 store, or if need be improve, the old and familiar expressions.’’ 
 
 In connection with this, by permission of the author, the following 
 note is presented;— 
 
 “Boston, Septemher 28, 1863. 
 
 % 
 
 “Dear Sir: Many thanks for the two numbers of the Dental Cos¬ 
 mos, and for the compliment paid an article of mine by taking it as the 
 text of your interesting remarks. The subject is one of great interest, 
 and will, I hope, receive a fuller development at your hands hereafter. 
 
 “ I am, dear Sir, 
 
 “Yours very truly, 
 
 “O. W. HOLMES.” 
 
 In giving the subject a “fuller development,” my aim has been to 
 treat it in a suggestive manner, so that a spirit of inquiry might be 
 awakened in a direction not only attractive and instructive in its nature, 
 but also capable, if the information gained is rightly applied, of being 
 made subservient to the comfort and happiness of others. 
 
 Within the limits of two brief addresses it was of course impossible to ^ 
 enter upon the minute description of structure, or to make that extended 
 practical application of which the subject is susceptible. This can only 
 be done in a regular and systematic course of lectures. Recognizing the 
 importance of such a course, it has ever been my practice, as a public 
 teacher, to present these and analogous subjects to the attention of stu¬ 
 dents in the broadest, most extended, and practical manner possible, in 
 my winter course of lectures on Anatomy, Physiology, and Hygiene. 
 
 J. H. McQ. 
 
 1112 Arch Street, Philadelphia, 
 
 July, 1864. 
 
ANATOMY AND PHYSIOLOGY OF EXPRESSION. 
 
 An Address delivered before the Odontographic Society. 
 
 Gentlemen: —As the essayist of the evening, having no paper ready 
 to present, my remarks of necessity will be of an oral character. The 
 subject I have selected for your consideration is one which should, 
 and more or less actually does, interest everybody; for although on 
 the part of the many there may not be a recognition of the fact, 
 every one is somewhat of a physiognomist; or, in other words, intu¬ 
 itively seeks within the few square inches of the “human face divine,’^ 
 to discover the mental and social qualities and past experiences of 
 those with whom he is brought in contact, by the relations of busi¬ 
 ness or pleasure. And there the indelible record is made of the mental 
 training, the high and ennobling, or the low and degrading association, 
 and the joys and sorrows each individual being has experienced. Erro¬ 
 neous estimates may be, and frequently are made by the most acute ob¬ 
 server, but this is no evidence that the most legible and unmistakable 
 record was not presented in each instance. An opinion of any value is 
 not to be formed by carelessly and indifferently observing the features when 
 in repose, or noting a few changing expressions ; but by a careful and 
 philosophical examination under all their varying and chamelion-like 
 forms. A false estimate of character may sometimes be due to the fact 
 that the opportunities and circumstances attending the examination have 
 not been of such a nature as to disclose all the face was capable of re¬ 
 vealing ; for as a single word often gives a clear insight of the life and 
 animus of an individual, so a single look, indicative of love or hate, 
 hope or despair, will reveal traits of character which the individual fully 
 recognizes the possession of, and studiously endeavors to conceal from the 
 observation of the world. 
 
 Aside from this general interest shared by all in the human face, it is 
 important that those engaged in certain departments of life should be¬ 
 come thoroughly acquainted with the mechanism, so to speak, by which 
 the record is made. To the speaker, whether in the pulpit, at the bar, 
 or on the stage, gesture is all-important; to the artist, whether as a 
 
 O) 
 
8 
 
 painter or sculptor, expression is everything; and last, though not least, 
 to the dentist a faithful discharge of duty demands that he should, in 
 the performance of his operations on the teeth, invariably endeavor to 
 preserve the natural expression of the face, or when the ravages of de¬ 
 cay have eventuated in the loss of the dental organs, that the lost expres¬ 
 sion should be restored by the introduction of properly constructed and 
 adapted artificial substitutes. To each and all of these, and particularly 
 to the latter, if they desire to attain the highest possible point of excel¬ 
 lence, an intimate acquaintance with the anatomy and physiology of ex¬ 
 pression is indispensable. In the brief space allotted to me this evening, 
 little more can be done than to offer, in a general manner, the ground¬ 
 work on which such an interesting and extended study rests. It would 
 require many evenings,'and fill a large sized volume, to do full justice 
 to the theme. With this understanding, permit me in the first place to 
 direct your attention to the main characteristics of the bony framework ^ 
 on which the features rest, for in the language of Tennyson,— 
 
 “Every face, however full, 
 
 Padded round with flesh and fat, 
 
 Is but modeled on a skull.” 
 
 The roundness and fullness of some faces, the sharp and pinched ap¬ 
 pearance, or the.long and heavy expression of others, is mainly due to 
 the shape and size of the bones on which the features are moulded. In 
 illustration of this, yon see on the table a number of cranim, ranging 
 from the earliest period of infancy to childhood, adolescence, manhood, 
 and extreme old age; and in addition, others belonging to different races, 
 each and all indicating, in a marked degree, the characteristic differences 
 just referred to. In this, for instance, the skull of an infant a month or 
 so after birth, all that portion which contained the brain is relatively 
 large, with a full forehead, but rather flat at the eyebrows, while the 
 bones of the face are diminutive, and their external surface smooth and 
 rounded; no great prominences and depressions, with the exception 
 of the orbital cavities, are presented, and everything contributes to 
 give the plump and meaningless expression characteristic of an in¬ 
 fantile face while in repose. Passing to another skull belonging to 
 a child set. six, the bones of the face are found largely increased in 
 size, and this, along with the presence of the deciduous teeth, serves to 
 lengthen the face, and make it less round than that of the infant. The 
 gradual but marked increase of size in the superior maxillae presented 
 in these skulls, as we pass from infancy to childhood, from childhood to 
 adolescence, and from adolescence to manhood, is accompanied by a pro- 
 ortionate enlargement of the Antrum Highmorianum; at the same 
 
9 
 
 time, as the centre bones of the face, their growth has the effect of in¬ 
 creasing the length and prominence of the nasal and malar, or cheek 
 bones. ^ The presence of the large permanent teeth of the adult, and the 
 alveolar processes which support and fix them, serve also to increase the 
 length, breadth, and depth of the superior and inferior maxillae; and the 
 entire face consequently becomes larger and longer, but not necessarily 
 fuller. In the great majority of cases, indeed, along with the increased 
 size and lengthened visage, there is a decided and proportionate loss of the 
 roundness and fullness presented in the infantile period. The reason for 
 this is obvious, when observing the great prominence of the nasal and 
 malar bones, and the corresponding depressions in the other parts of the 
 face, particularly the canine fossa3 of the superior maxilla. In life, when 
 these depressions are not well “padded round with fat,” the cheeks of 
 course present a wan and sunken appearance. In the series here pre¬ 
 sented, while the bones of the face have gradually increased in size, those 
 of the cranium have maintained a proportionate relation. This promi¬ 
 nent ridge in particular, (the supra-orbital,) in the frontal bone of 
 this very fine and perfect adult skull, and which has much to do with ex¬ 
 pression, is owing to the gradual separation of the external and internal 
 plates of the os frontis at this point, so as to form the frontal sinus. On 
 this ridge the eyebrows rest, although they are usually described as rest¬ 
 ing on the superciliary ridge; but this is not correct. 
 
 It is generally conceded that the proportionate relation of the bones of 
 the face to those of the cranium has much to do with the moral and 
 mental qualities of the individual; in other words, that .a high order 
 of intellect is usually manifested by those in whom the cranium is large, 
 the forehead broad and high, and the bones of the face small; while the 
 animal propensities are generally evinced in a marked degree, and pre¬ 
 ponderate over the intellectual in those with depressed foreheads, com¬ 
 pressed temples, and large and massive jaws, as in the case of this emi¬ 
 nently prognathous skull of an African, with whose antecedents I was 
 made acquainted by the gentleman who presented the specimen to me. 
 The record in his case is in full confirmation of the position just advanced. 
 
 The opposite extreme is sometimes presented, in which the bones of 
 the face are so disproportionately small, in comparison with the cranium, 
 as to constitute a marked deformity. Again, a want of harmony between 
 the different bones of the face is occasionally presented; as, for instance, 
 when the inferior maxilla is very large and massive, or unusually small, 
 in comparison with the superior maxilla, or vice versa. This hyper¬ 
 trophied or atrophied condition may occur in any of the bones, and of 
 course when existing will mar the harmony of the surrounding parts. 
 
 In extreme old age, the atrophied condition of the jaws (markedly 
 
10 
 
 manifest in this skull, belonging to a very old person) due to the gradual 
 loss of all the teeth, and the absorption of the alveolar processes, pro¬ 
 duces that decided alteration in the features of the aged with which we 
 are all so familiar. The change which invariably takes place in the 
 angle of the lower jaw in consequence of the disappearance of the teeth 
 and processes, causes the chin to project, and when the jaws are closed 
 the nose and chin approximate each other. Even when apart, the falling 
 in of the lips so encroaches upon the oral cavity as to make it too small 
 for the tongue, and thus renders the speech feeble and indistinct It is 
 here where the skill of the mechanical dentist finds a field for artistic la¬ 
 bor, not only by replacing the lost expression of the face, but also by 
 restoring the medium through which the wants and thoughts of the indi¬ 
 vidual are made known to others. 
 
 Arising from various parts of the bony framework, and then mainly 
 converging to one or the other of the two great centres of expression, 
 the eyes and mouth, there are a number of muscles on whose action the 
 varying play of the features depends. Intending by no means to give, at 
 this time, a lengthy and detailed description of these muscles, but rather 
 to notice them casually, with the aid of the drawings, and the large pa¬ 
 pier-mache manikin here presented, I hope to make myself clearly under¬ 
 stood. We will commence with 
 
 The Occipito frontalis (1, 2, 3,) consists of two broad but fleshy 
 bellies, with an intervening aponeurosis resting upon the arch of the 
 skull, .and over which it slides; the posterior portion of the muscle 
 arises from the superior curved line of the occipital bone. The prin- 
 
 pal parts of the anterior fibres are 
 inserted, or blend with the corru- 
 gator supercilii, and the superior 
 j^argin of the orbicularis palpebra¬ 
 rum. The minor portions of the 
 right and left frontal muscles unite 
 together some space above the root 
 of the nose, and are inserted at this 
 point and send down fibres which 
 are continuous with the pyramidalis 
 nasse. Function, It moves the 
 scalp, elevates the eyebrows, and 
 induces the transverse wrinkles of 
 the forehead. 
 
 The Corrugator Supercilii lies 
 under the occipito frontalis, and is 
 
 a small, pyramidal muscle, arising from the inner extremity of the super- 
 
11 
 
 ciliary ridge; its fibres proceed outward from their origin and blend with 
 those of occipito frontalis and orbicularis palpebrarum. Function. It 
 draws the eyebrows and eyelids inward, and produces the vertical wrin¬ 
 kles of the forehead. 
 
 The Orbicularis Palpebrarum (4) consists of a thin, flat plane of 
 elliptical fibres, which extend around the whole circumference of the 
 orbit and eyelids. It spreads outward on the temple and downward on 
 the cheek, but the only fixed points of attachment, however, to bone are 
 at the inner margin of the orbit. Function. It closes the eyelids. 
 
 The Pyramidalis Nasi (5) is usually regarded as a prolonged slip of the 
 occipito frontalis, which continues downward on the bridge of the nose 
 where it blends with the compressor nasi. Function. It draws down 
 the inner angle of the eyebrows, and produces the transverse wrinkles on 
 the bridge of the nose. 
 
 The Levator Labii Superioris Alseque Nasi (8) is a thin, triangular 
 muscle, arising from the upper part of the nasal process of the superior 
 maxilla by a pointed extremity, and, as it descends along the side of the 
 nose, gradually increases in breadth, and then divides into two slips, one 
 of which is inserted into the ala of the nose, and the other blends with 
 the orbicularis oris. Function. It elevates the upper lip and ala of 
 the nose, and dilates to a considerable extent the latter organ. 
 
 The Compressor Nasi (6) arises narrow and fleshy from the canine fossae 
 of the superior maxilla, and its fibres continuing upward and inward ex¬ 
 pand into a thin aponeurosis which unites on the dorsum of the nose 
 with that of the muscle of the opposite side. Function, The compressors 
 may act either as dilators or as constrictors of the nares. 
 
 Depressor Labii Superioris Alseque Nasi, covered by the orbicularis 
 oris, arises from the myrtiform fossae of the superior maxilla, as a short 
 radiating muscle, whose fibres diverge upward and outward; the ascend¬ 
 ing fibres terminate in the septum and back part of the ala of the nose; 
 the others curve forward and blend with the upper portion of the orbic¬ 
 ularis oris. Function. It draws the upper lip and ala of the nose down¬ 
 ward, and thereby constricts the anterior nares. 
 
 The Levator Labii Superioris Proprius (9) arises from the lower 
 margin of the orbit, where it is attached partly to the superior maxilla, 
 and partly to the malar bone; its fibres pass downward and inward, 
 and blend with the upper part of the orbicularis oris. Function. It is 
 the proper elevator of the upper lip, and at the same time carries it a 
 little inward. 
 
 The Levator Anguli Oris, covered by the preceding and the zygo- 
 matici muscles, arises from the canine fossae just below the infra-orbital 
 foramen, and its fibres pass downward and outward to be inserted into 
 
12 
 
 the orbicularis oris at the angle of the mouth. Function. It raises the 
 angle of the mouth and draws it inward. 
 
 The Zygomaticus, Major and Minor, (10, 11,) arise, the latter in front 
 of the former, from the malar bone, and then pass downward and outward 
 to the upper lip and angle of the mouth, where their fibres blend with 
 the orbicularis oris. Function. They raise the upper lip and draw the 
 corners of the mouth outward, as in laughing. 
 
 The Levator Lahii Inferioris (14) arises from the incisive fossae of the 
 lower jaw external to the symphysis; the fibres pass downward and a 
 little forward to be inserted into the chin. Function. It raises and pro¬ 
 trudes the lower lip. 
 
 The Depressor Lahii Inferioris (12) arises from the oblique line of the 
 inferior maxilla, just in front of the anterior mental foramen; it is a quad¬ 
 rilateral shaped muscle, and its fibres pass upward and outward to be in¬ 
 serted into the lower lip. Function. It draws the lower lip downward 
 and a little outward. 
 
 The Depressor Anguli Oris (13) arises from the external oblique line 
 of the lower jaw by a broad base, and its fibres converge as they pass up¬ 
 ward to be inserted into the angle of the mouth, where they unite with 
 the orbicularis oris, the zygomaticus major, and the levator anguli oris. 
 Function. It draws the corners of the mouth downward, and is the an¬ 
 tagonist of the muscles just named; when they all act together, the mouth 
 is drawn backward. 
 
 The Buccinator (18) is a broad, thin muscle, arising from the outer 
 border of the pterygo-maxillary ligament, and the external surface of the 
 alveolar processes of the upper and lower jaw, commencing at the first mo¬ 
 lar tooth and passing backward. The fibres of the muscles converge, and 
 are inserted into the angle of the mouth and the upper and lower lips. 
 Function. It compresses the cheek, so as to assist mainly in driving air 
 y from the oral cavity, as in blowing on wind instruments. 
 
 The Orbicularis Oris (I) is a great sphincter muscle surrounding the 
 mouth, and although it has no bony origin or insertion, as we have found, 
 a large number of muscles arising from the different bones of the face 
 centre here and blend their fibres with those of this muscle. Function. 
 It closes the lips. 
 
 While the muscles already described as the superficial muscles of the 
 . face are mainly concerned in the varying expressions of the countenance, 
 it must be remembered that those deep-seated muscles, the temporal, mas- 
 seter, and external and internal pterygoid, which are the active agents in 
 the comminution of food, sometimes play an important part in expression. 
 This is markedly manifest in the aged after the loss of the dental organs, 
 with whom the shortening of the face, the protrusion of the jaw, and the 
 
 
13 
 
 approximation of the nose and chin, under such circumstances, are due to 
 the contraction of these muscles and the influence which they exert in 
 modifying the shape of the lower jaw, by altering the angle which the 
 ramus forms with the body of the bone in early manhood. Considerations 
 such as these indicate the propriety of a brief description of these mus¬ 
 cles, in connection with the subject under consideration. The first of 
 these, 
 
 The Temporalis, arises from the entire temporal fossae and forms a 
 broad, radiating muscle whose fibres, as they descend, converge into a 
 flat tendon which is inserted into the inner surface of the coronoid process 
 of the lower jaw. Function. It raises the lower jaw. 
 
 The Masseter (15) is a quadrilateral-shaped muscle, and arises from the 
 malar process of the superior maxillae and the zygomatic arch, and is 
 inserted into the posterior third of the outer surface of the body of the 
 lower jaw, and the ramus from the coronoid process to the angle. It 
 has two planes of fibres, superficial and deep. The first pass downward 
 and backward, the second downward and forward. Function. It draws 
 the lower jaw upward and forward, or upward and backward. 
 
 The Pterygoideus Externus arises (1) by two heads from the pterygoid 
 ridge of the great ala of the sphenoid bone, the outer surface of the ex¬ 
 ternal plate of the pterygoid process, and 
 part of the tuberosity of the palate bone; 
 and its fibres pass horizontally backward and 
 outward, to be inserted (2) into the neck of the 
 condyle of the lower jaw. Function. When 
 the two muscles act together they draw the 
 inferior maxilla directly forward, so as to 
 make the lower front teeth project beyond 
 those of the upper. The protrusion of the 
 chin in those who have lost their teeth is 
 greatly due to this fact. The lateral sliding motion of the lower jaw in 
 mastication is effected by the alternate contraction of the muscles of the 
 right and left sides. 
 
 The Pterygoideus Internus, (3,) like the masseter, is quadrilateral in 
 form, and arises from the pterygoid fossa of the sphenoid and the tuberosity 
 of the palate bones; its fibres pass outward, downward, and backward, to 
 be inserted info the inner surface of the ramus and angle of the lower jaw. 
 Function. It draws the lower jaw upward, and, from the obliquity of its 
 fibres, also assists the pterygoideus externus in carrying the jaw forward 
 and from side to side. 
 
 There are other muscles, in addition to those just described, which are 
 somewhat concerned in expression. Among these are the depressors of 
 
14 
 
 the lower jaw and the other muscles of the neck, by means of which the 
 head is thrown into various positions, under the influence of the different 
 passions; but it would be foreign to the subject to present even a brief 
 description of them. It is proper, however, to refer to the ocular group 
 of muscles, for the eye is not only one of the most prominent features of 
 the face, but also one of the most expressive. When the rest of the face 
 is so completely under the control of the will that it is impossible to de¬ 
 termine what is passing in the mind of another, the eye frequently reveals 
 everything. So true is this that, when the tongue says one thing and the 
 eye another, men of observation and experience invariably believe the 
 latter. It is the position of the organ, whether in the sidelong, upward, 
 or downward glance; the fixed, prolonged gaze, or the restless, roving 
 motion, that serves as a key, unlocking to the mind of the attentive ob¬ 
 server that which another is striving to conceal. The muscles by which 
 these varied movements of the organ are effected are six in number, and 
 consist of two groups, the first of which are four straight muscles, the 
 Rectus Superior, Inferior, Externus, and Internus; the second group 
 is formed by two oblique muscles, the Obliquus Superior and Inferior. 
 In addition to moving the eye upward and downward and from side to 
 side, if all the muscles of either group act together, a retraction of the 
 eyeball is induced by the contraction of the Recti, or a protrusion of the 
 ball by similar action on the part of the oblique. Squinting or strabis¬ 
 mus, either convergent, looking inward, or divergent, looking outward, 
 which gives such a peculiar expression to the face, is due to a want of 
 harmonious action in the ocular group, and may be caused by overac¬ 
 tion or paralysis of a muscle from cerebral disturbance; or it may be the 
 result of imitation. The Levator Palpebra, which is included in this 
 group, is the elevator of the eyelid. 
 
 The muscles described, like the bony framework on which they rest, 
 would be without motion but for their connection with the brain, through 
 the medium of special nerves, whose function is to give to the various 
 parts of the face that vitality and ever-changing expression which consti¬ 
 tutes the charming attraction of the human countenance. 
 
 Of the twelve pair of cranial nerves, five pair are concerned in expres¬ 
 sion, and three of them are distributed to and give motion to the muscles 
 of the eye. Thus the third pair of nerves, or the motor oculi, sends 
 branches to all of these muscles, with the exception of the motor externus 
 and the obliquus superior, to the first of which pass the fourth pair, 
 or motor externus nerve, and the second is connected with the sixth 
 padr, or Nervus Pathetici. 
 
 The and seventh pair of nerves are distributed to the muscles of 
 the face; the latter, also named portio dura, or facial, emerges from 
 
15 
 
 the stylo-mastoid foramen, and then," passing through the parotid gland, 
 is eventually distributed exclusively to the superficial muscles in the form 
 of a plexus, named pes anserinus. It is purely a motor nerve, upon the 
 integrity of which the expression of the countenance and the varied play 
 of the features depend. This has been demonstrated in the most satis¬ 
 factory manner by experiments on animals and in pathological conditions 
 in man. Strange as it may appear now, it was formerly supposed that 
 the painful affection named tic Douleureux was seated in this nerve, and 
 resection of it at the stylo-mastoid foramen was frequently performed for 
 the relief of patients, but with no other result than inducing paralysis of 
 the superficial muscles and loss of expression on the side of the face oper¬ 
 ated upon, the patients being unable to close the eyelid, elevate the ala 
 nasi, or move the cheek or that side of the lips, and yet at the same time 
 still suffering as much from the disease. Paralysis of this nerve is some¬ 
 times induced by cerebral disturbance or the presence of a tumor beneath 
 the ear, and is usually denominated Bell’s palsy, on account of the true ' 
 nature of the affection having been made known by Sir Charles Bell, to 
 whose genius and laborious experimental research the world is greatly 
 indebted, not only for their kn|)wledge of this disease, but also for 
 much that is known at present of the nervous system. Paralysis of the 
 Portio Dura does not affect in the slightest degree the function of 
 temporal masseter or pterygoid muscles, (and therefore interfere with 
 mastication,) as they derive their nerve force from the motor branch 
 of the fifth pair. The dependency of these muscles on the motor branch 
 of the fifth can be readily demonstrated by divisions of the nerve on each 
 side in animals, when the lower jaw at once falls, and the subject oper¬ 
 ated upon is rendered incapable of raising the jaw or masticating its food. 
 
 If the nerve of one side only is cut, the parallelism of the jaw is destroyed; 
 or, in other words, the muscles of the side operated upon being paralyzed, 
 fail to bring the jaw in contact with the upper, while on the sound side 
 it is effected as usual. 
 
 Premising that sufficient has been said with regard to the points already 
 touched upon, we will now pass to the consideration of some of the ex¬ 
 pressions presented by the countenance when under the influence of the 
 different passions that affect the mind of man. It is impossible to de¬ 
 scribe all of these; and the attempt, at best, in the consideration of those 
 to which your attention will be directed, must of necessity be merely sug¬ 
 gestive to you of an interesting and instructive subject of study, which 
 for years has more or less intuitively engaged my attention : whether 
 when in conversation with others, quietly observing them when engaged 
 in the pursuit of business or pleasure; or watching the delineations of the 
 orator, the actor, the artist; and last, though not least, the truthful rev¬ 
 elations of the photograph. 
 
16 
 
 In illustration of this part of the subject, I shall employ a number of 
 drawings, here presented, portraying the different expressions, which are 
 faithful copies of the admirable engravings in Sir Charles Bell’s work on 
 the Anatomy and Philosophy of Expression, and I not only cordially 
 acknowledge the pleasure derived from the perusal of his eloquent work, 
 but shall be most happy if in the following remarks I succeed in present¬ 
 ing a fair synopsis of his extended description of the subject in connec¬ 
 tion with my own observations and thoughts. 
 
 All the facial expressions may be classified under two heads—the ex¬ 
 hilarating apd the depressing; and the angle of the mouth and the inner 
 extremities of the eyebrows as points where a number of muscles concen¬ 
 ter are the most movable parts of the face, and on whose changes expres¬ 
 sion chiefly depend. No better illustration of this fact can be afforded 
 than in the caricature, with which every one is familiar, representing two 
 faces joined together, in one of which the elevation of the angles of the 
 mouth gives a most joyous expression to the face; on reversing or turn¬ 
 ing the picture upside down, however, depression of the same mouth at 
 the angles produces a correspondingly despondent expression in the other 
 face. ^ 
 
 Commencing with laughter, you will observe in this picture that the 
 various muscles which have been described as inserted into the orbicu¬ 
 laris oris, have entirely overcome the action of that muscle whose func¬ 
 tion is to close the lips. When a ludicrous idea enters the mind, as a 
 general thing it is in vain to try to keep the mouth closed. The antago¬ 
 nistic muscles concentering there exert a force beyond all control, and 
 frequently the more determined the effort not to give way to the inclina¬ 
 tion, the more marked and explosive eventually becomes the demonstra¬ 
 tion. The elevator muscles, inserted in the upper lip and the angles of 
 the mouth as the active agents in drawing the mouth upward, produce a 
 fullness of the cheeks which, pressing upon the lower eyelids, throws the 
 skin into wrinkles under them. At the same time the teeth are exposed; 
 while by the contraction of the orbicularis palpebrarum the eyes are 
 almost concealed, and, by compression of the lachrymal gland, frequently 
 suffused with tears. Together with this, the agitation of the muscles of 
 the throat, neck, chest, and diaphragm produce audible cachinations. 
 
 In the reverse of this, or weeping, the lips are drawn apart by the con- 
 verging muscles, but in place of the elevation of the corners of the mouth 
 they are now drawn downward by the depressor anguli oris; the nostrils, 
 at the same time, are dilated, and the tears flow profusely from under the 
 convulsively-closed eyelids over the flushed cheeks; while the veins of the 
 forehead are distended and the inner part of the eyebrows are drawn up¬ 
 ward and inward by the combined action of the corrugator supercilii 
 
0 
 
 IT 
 
 and the occipito-frontalis. The muscles of the throat, chest, and dia¬ 
 phragm are spasmodically affected and the respiration is frequently inter¬ 
 rupted by sobs. 
 
 Bodily pairiy the manifestation of which, in the face of our patients, is 
 to us frequently an important means of diagnosis, not only in children, 
 but those of a larger growth, is a condition that particularly claims our 
 attention from a professional and humanitarian point of view. Here let 
 me say, in passing, that pain is by no means what it is usually regarded, 
 an unmixed evil. Paradoxical as the statement may appear, it is fre¬ 
 quently a blessing rather than a curse, as it is the chief means by which 
 we become aware that some important organ is diseased. Without such 
 intimation, the part affected might have become disorganized to such an 
 extent as not only to destroy the function of the organ, but also to place 
 even life itself in jeopardy. This applies with peculiar force to those 
 organs which it is our duty to save; for it is the unpleasant sensation of 
 pain which generally drives our patients to us, and it is the various mani¬ 
 festations induced by the pain endured which enables the experienced 
 practitioner to determine the nature and extent of the difficulty. 
 
 , In extreme pain, (except in cases where the patient is suffering from 
 periodontitis, when the occlusion of the jaws intensifies the suffering,) the 
 teeth are brought together with great force and ground against each 
 other by the temporal, masseter, and pterygoid muscles; the saliva fre- 
 • quently flows in large quantities from the mouth, which is drawn open 
 laterally; the face is flushed, the veins distended, the nostrils dilated, the 
 eyebrows raised, the forehead thrown into horizontal wrinkles, the eyelids 
 widely opened, and the tears'coursing over the cheeks, betray, in the 
 most unmistakable manner, the suffering endured. 
 
 In fear, the head sinks backward between the elevated shoulders; the 
 eyes are fixed and staring; the eyebrows are raised to their utmost by 
 the occipitofrontalis, which, in addition to a contracted state of the scalp, 
 causes the hair to stand on end; the face is ghastly pale, and the cheeks 
 hollow, shrunken, and in convulsive motion, like lips which are wide open, 
 owing to the dropping of the lower jaw; the breathing is shorty labored, 
 and spasmodic. 
 
 In rage, the inflamed and glaring eyeballs, owing to the contraction of 
 the oblique muscles, seem ready to dart from their sockets; the brow is 
 thrown into deep vertical wrinkles by the corrugators; the nostrils are 
 dilated; while through the clinched teeth but open mouth words of hate 
 are delivered with emphatic force. 
 
 In joy, the face is lighted up with a smile by the gentle elevation of 
 the eyebrows, the lively and sparkling appearance of the eye, and the 
 pleasant expression of the mouth, which, without being separated, is 
 drawn aside at the corners. v 
 
Conscious of the time already absorbed, and desiring to hear from some 
 of the gentlemen who are present from a distance, we will pass over the 
 consideration of other facial expressions which might be referred to, trust¬ 
 ing that those which have been so hurriedly described may awaken a 
 desire on the part of all to acquire a thorough and accurate knowledge 
 of the entire subject, and to make that practical application of the knowl¬ 
 edge thus gained of which it is susceptible, but which it does not come 
 within the province of this address to make. 
 
THE 
 
 TEETH 
 
 IN THEIR 
 
 RELATIONS TO MASTICATION, SPEECH, AND APPEARANCE.^ 
 
 An Address delivered before the Delaware Dental Association. 
 
 Gentlemen :—In compliance with your appointment I appear before 
 you this evening,—not, however, as an essayist, for my time has been so 
 much engrossed by various duties since the nomination as to preclude 
 the possibility of preparing a written address, but rather in an oral com¬ 
 munication, which to me, from years of habit in the lecture-room, is de¬ 
 cidedly preferable, to invite your attention to the consideration of the 
 Human Teeth in their Relations to Mastication^ Speech, and Appear¬ 
 ance. 
 
 The varied and extended character of the subject demands that it 
 should be treated in a general and suggestive manner; and my object in 
 selecting it was, that it might awaken a spirit of inquiry in these various 
 directions, and that the knowledge thus obtained might be made instru¬ 
 mental in securing to patients beneficial, practical results. 
 
 To prevent confusion and secure clearness of conception, it will be 
 advisable to consider the subject under separate heads, commencing with 
 the first. 
 
 Mastication. —It may be truly said that a just appreciation of the 
 position which the human teeth occupy as masticating agents, can only 
 be obtained by familiarity with the comparative anatomy of the dental 
 organs; for in the structure of the teeth there are certain characteristic 
 differences, corresponding with the habits of the animal and the kind of 
 food upon which it subsists; and in the mouth of man teeth are found 
 belonging to different classes of animals, whose habits and food are of the 
 most opposite character. In illustration of this point, the craniae of man 
 and various animals, lying on the table, are presented. 
 
 The illustrations accompanying this communication were engraved from speci¬ 
 mens in my possession.—J. H. McQ. 
 
 3 
 
 ( 19 ) 
 
20 
 
 With regard to the entire animal series, the teeth may be defined as 
 hard organs situated on the inner surface of the digestive canal, varying 
 in shape, size, number, and location, with the character of the materials 
 which they are intended to comminute. By some animals they are em¬ 
 ployed as offensive and defensive weapons in prehension; by others, as 
 organs of locomotion; again, they are used by certain kinds of fish in 
 crushing the stony shells inclosing their food; as in the case of the 
 sheep^s-head fish and the parrot-fish, {scari.) 
 
 Although man and several of the animals have thirty-two teeth belong¬ 
 ing to the permanent set, the typical number of the vertebrates is forty- 
 two. Some of them, however, are edentulous, or without teeth; others 
 have but one tooth, and from this they range upward to such a large 
 number, that to those who have not examined the subject, it must appear 
 incredible. Thus birds are found invariably edentulous, the gizzard 
 serving as the comminuting organ; while at the other extreme, fish 
 are supplied in the most liberal manner with teeth. In many of the 
 vertebrates the teeth are firmly implanted in the maxillary and pre¬ 
 maxillary bones. In other cases, as in certain kinds of fish, the teeth are 
 inserted not merely in the maxillary and premaxillary bones, but in the 
 palate bones, vomer, pharynx, on the tongue, and in the stomach; being 
 so numerous, and in such peculiar positions, that it is quite difficult to 
 count them; running as high as one hundred and forty in some, and in 
 others to one hundred and ninety, and beyond. Wherever found, while 
 they may subserve other purposes, they are invariably necessary agents 
 in the prehension or comminution of food. 
 
 In fish and serpents, with the exception of the poison-fangs of ven¬ 
 omous reptiles, the teeth are merely organs of prehension, and prevent 
 the escape of the prey after being seized; and which, as a general thing, 
 is swallowed entire. 
 
 The comparative anatomist, in making the diet a means of classifica¬ 
 tion—as in the carnivorous and herbivorous animals—takes advantage of 
 certain marked characteristics in the digestive apparatus to divide these 
 animals. These peculiarities, however, are not confined to the dental or¬ 
 gans only, but a constant relation is maintained between the shape and 
 structure of the teeth; the articulation of the jaw; the form of the 
 stomach; the length of the intestines, and the nature of the food on 
 which the animals, subsist. 
 
 Thus the teeth of the truly carnivorous animals are fitted to seize their 
 prey and lacerate the food, but not to thoroughly masticate it. These 
 organs are of three kinds, and adapted to different mechanical purposes. 
 Thus, in the polar bear, the incisors —six in the superior and six in 
 the inferior maxillae —are so formed and situated as to serve as shears 
 
21 
 
 in dividing the food. The canines —two above and two below—long, 
 curved, and sharp-pointed tusks, possessing great strength, and deeply 
 and firmly implanted in the jaws, are used by the animal as offensive and 
 defensive weapons, and for seizing upon and holding its struggling prey. 
 The molars —four on each side, above and below—have cutting or trench¬ 
 ant crowns, with serrated edges and sharp points, which are arranged in 
 a direction parallel with the line of the jaw ; and the superior teeth have 
 a flat inner side, against which the inferior works like a scissor-blade. 
 
 POLAR BEAR. 
 
 These teeth serve to mangle rather than thoroughly comminute the food 
 of the animal. The jaws are strong, and the deep and narrow glenoid 
 cavities in the temporal bones receive the condyloid processes of the in¬ 
 ferior maxillge in such a manner as not to admit of any horizontal motion, 
 either backward or forward, or from side to side. This articulation, 
 constituting the pure ginglymous, or hinge-like joint, affords the lower 
 jaw only the upward and downward movements. In addition to this, the 
 wide and deep temporal fossae give an extensive origin to the immense 
 temporal muscles inserted into the coronoid processes of the lower jaw; 
 and the zygomatic processes are very strong and prominent, and the 
 masseter muscles arising from them, and inserted into the rami and body of 
 the lower jaw, are large, broad, and powerful; while the pterygo-maxillary, 
 and pterygoid fossm, giving origin respectively to the external and inter¬ 
 nal pterygoid muscles, are, comparatively speaking, quite shallow, and the 
 muscles small. By this arrangement in the shape and position of the 
 teeth, the articulation of the jaw, and the origin and insertion of the 
 muscles, the animal is enabled to seize upon and hold its prey. Any 
 other kind of joint, under such circumstances, would prove not merely 
 unreliable, but actually worthless. In the carnivora the stomach is sim¬ 
 ple, and the intestinal canal is remarkably short in relation to the length 
 of the body. 
 
 Passing to the herhivora, and selecting the horse as an example of 
 this class, the incisors— six in number in both jaws—are arranged in a 
 
22 
 
 curve at the anterior end of the jaws, and are employed as prehensile , 
 organs in seizing upon and cutting off the herbage on which the animal 
 subsists. The canines, small in the horse, and rudimental in the mare, 
 are situated in the upper jaw, in the middle of the long interspace between 
 the incisors and molars, while in the lower jaw they are close to the outer 
 incisors. They subserve no purpose in mastication, this being effected 
 altogether by the molars ,—these are six in number, for each side of the 
 upper and lower jaws,—and the crowns of which present two double 
 crescents, the convexity being turned inward in the upper and outward in 
 
 MOLARS OF HORSE. 
 
 the lower ones. In addition to this, the triturating surface is found to 
 present a series of inclined planes, leading from prominent ridges to large 
 hollow cavities lying at their base; the inequalities thus presented being 
 due to the unequal wear of the different tissues composing the crown. 
 The grass, either in a green or dry state, on which the herbivora subsist, 
 containing as it does large quantities of pure silica or flint, produces 
 decided abrasion of the teeth, particularly the molars. If the teeth, 
 although presenting a rough masticating surface when first erupted, had 
 been composed of only one tissue, they would soon have worn smooth, 
 and proved inadequate to the service demanded. To meet this emer¬ 
 gency, therefore, the different tissues composing the teeth—the enamel, 
 dentine, and cementum—are arranged on the same plane. By such a 
 contrivance the teeth necessarily wear unequally, and always present a 
 rough, uneven, grinding surface to the food. 
 
 The glenoid cavities in the temporal bones of the horse and herbivorous 
 
 
 V 
 
23 
 
 animals generally are quite shallow, and the condyloid processes of the 
 lower jaw rounded. The joint thus formed not only admits of upward 
 and downward movements, but also of extensive sliding motions in every 
 direction. In addition to this, the temporal fossae are quite narrow and 
 shallow, the zygomatic processes not very prominent, and the temporal 
 and masseter muscles arising from them are feeble, in comparison with those 
 of the carnivora. The pterygo-maxillary and pterygoid fossae, however, are 
 quite deep, and the external and internal pterygoid muscles arising there¬ 
 from largely developed. By the action of these muscles the horizontal rub¬ 
 bing motion of the roughened surfaces of the superior and inferior molars 
 against each other is effected, and the coarse articles of food are thoroughly 
 triturated and reduced to a pulpy mass. One order of the herbivora—the 
 ruminantia —possesses the faculty of returning the food to the mouth 
 and subjecting it to remastication, after it has been once swallowed. 
 
 This is due to the remarkable arrangement and action of the stomach, 
 which, as in the cow for instance, is of immense size, and divided into 
 four compartments or stomachs. Another marked peculiarity of this 
 order is the absence of incisors and^ canines in the upper jaw. The 
 animal, when feeding, after slightly bruising the coarse vegetation by a 
 first mastication, swallows the bolus, which passes along the oesophagus 
 to the paunch or first stomach, and then by small portions to the second 
 stomach, where, after being subjected to an elevated temperature for some 
 time and mixed with the secretions, portions of it are compressed into 
 little pellets, which successively ascend to the mouth, to be rechewed; 
 after this is thoroughly effected, the food is again swallowed, and passes 
 on to the third stomach, a channel being formed through the first two by 
 the contraction of the groove or gutter made by the prolongations of the 
 oesophagus; here it remains a certain length of time, and then passes 
 into the fourth stomach, the true digesting organ, which is analogous to 
 the simple stomach of animals in general. 
 
24 
 
 In man the teeth occupy a position intermediate to those of the car¬ 
 nivorous and herbivorous animals. Twelve of the teeth, viz., the canines 
 and the bicuspids, correspond to those of the former; and twenty, the 
 incisors and molars, to those of the latter. The canines, however, are 
 much less prominent and pointed than in the carnivora; and the molars, 
 while they resemble those of the herbivora, in being thick and strong 
 and presenting comparatively flat surfaces, at the same time, in place of 
 the curvilinear ridges of the herbivora, have more or less conical emi¬ 
 nences like those of the carnivora. 
 
 HUMAN TEETH. 
 
 The form of the articulation of the lower jaw and the organs of diges¬ 
 tion, not less than the teeth, present strong evidence that man is truly 
 omnivorous, and afford a clear physiological argument in favor of the 
 mixed animal and vegetable diet which custom and tastd have decided to 
 be natural for the human species; while the vegetarian theory, which 
 rigidly excludes everything like animal food, under all the varying cir¬ 
 cumstances of climate and temperature, is in opposition to the indications 
 afforded not only by the structure, but also by the practice of man. 
 Millions, it is true, avoid flesh altogether, but millions also use it exten¬ 
 sively. In the torrid zone there is little or no occasion for its employ¬ 
 ment, while in the cold climates, particularly in the frigid zone, it is 
 imperatively demanded; and there is no fact more incontrovertible than 
 that the highest order of physical and mental development is found in 
 those countries where the inhabitants unite animal with vegetable food. 
 
25 
 
 As there are cutting, tearing, and grinding teeth in man, so the articula¬ 
 tion of the lower jaw is intermediate to those of the animal and vege¬ 
 table feeder. Thus the transverse condyles of the jaw are received into 
 the glenoid cavities, so as to admit of not only upward and downward, 
 but also of considerable lateral or sliding motion; and the temporal, 
 masseter, and pterygoid muscles effecting this, and the temporal fossae, 
 zygomatic processes, and the pterygo, maxillary, and pterygoid fossae from 
 which these muscles arise, hold the same intermediate relation to the 
 animals already referred to. By this arrangement the act of mastication 
 in man, unlike the simple laceration of the food on the part of the car¬ 
 nivora, can be as perfectly effected as in the herbivora; and although 
 the articles of diet are, to a great extent, freed from impurities and soft¬ 
 ened by cooking, this should be done; for, while some human beings are 
 in the habit of bolting their food, indulgence in such a practice is inva¬ 
 riably followed by the most unpleasant results.' The human stomach in 
 nowise resembles, as the practice of some would seem to indicate, the 
 gizzard of birds, where hard and otherwise indigestible substances can be 
 triturated; nor does it possess the faculty of returning imperfectly mas¬ 
 ticated food to the mouth for a second and thorough comminution, as 
 in the ruminantia; neither is it like the stomach of the carnivora, which 
 frequently digests with ease large portions of bone; but it is so constitu¬ 
 ted as to demand the most perfect and minute division of the food in the 
 mouth. It .is truly said that food well chewed is half digested. If, in 
 place of this, it is swallowed in undivided masses, it becomes a source of 
 irritation by remaining a long time undissolved in the stomach; and, if 
 this practice is continued for any length of time, dyspepsia, with its at¬ 
 tendant train of horrors, is evoked. The Americans, in their all-absorb¬ 
 ing pursuit of business or pleasure, perhaps more than any other people 
 on the globe, violate, in the most reckless manner, this canon, and, as a 
 consequence, lantern jaws and disordered stomachs are universally pre¬ 
 sented to view. If more time was devoted to the thorough mastication 
 of the food, in place of being time wasted, it would result in increased 
 comfort, physical and mental power and endurance, and length of years. 
 
 Passing now to the second section of our subject, or the consideration 
 of— 
 
 Speech, it will be advisable, in the first place, to define the exact differ¬ 
 ence between voice and speech; for it is a common error, even among 
 persons of education, to speak of them as if they were one and the same 
 thing, and yet that such is not the case will be evident on the slightest 
 reflection. 
 
 Voice is possessed not only by man but also by all of the vertebrata having 
 
26 
 
 lungs, and it results from the vibrations induced in the vocal chords as 
 the air expelled from the lungs passes through the glottis. The sound 
 thus created is capable of being variously modified during and after its 
 production, and it is owing to the mutations induced by the motions of 
 the pharynx, the velum, the tongue, the lips, and other parts of the 
 mouth, that speech or articulated voice is produced in man, and in con¬ 
 nection with his moral and mental endowments places him above, and gives 
 him dominion over the brute creation, and enables him not only to make 
 known his wants, experience, and thoughts to his fellow-man in his own 
 day and generation, but also by the aid of the written and printed record 
 to transmit them from age to age, thus insuring the constant and pro¬ 
 gressive development of man's moral and mental powers, and contributing 
 to his physical comfort and well-being. 
 
 In the construction of the vocal organs in man nature appears to have 
 combined the double mechanism of wind and string instruments, and it is 
 on this account that it surpasses all musical instruments, by the extent, 
 the perfection, and, above all, by the inexhaustible variety of its effects. 
 Advantage is taken of the function of respiration to convert into a sound¬ 
 ing instrument the passages formed by the trachea and larynx, through 
 which the air is admitted to and expelled from the lungs. The larynx 
 is a sort of cartilaginous box placed at the upper end of the trachea, and 
 is composed of five distinct pieces, the thyroid, the two arytenoid, the 
 epiglottis, and the cricoid cartilages, which are readily moved on each 
 other by appropriate muscles. 
 
 The thyroid, which forms the uppe^r and fore part of the larynx, con¬ 
 sists of two lateral wings of a quadrangular shape, united in front in a 
 longitudinal angle, which gives the prominence to the fore part of the 
 throat, observable in men, named pomurn Adami. From the posterior 
 corners of the wings four processes project, which are called the superior 
 and inferior cornua. The cricoid cartilage, below and behind the thy¬ 
 roid, is shaped somewhat like a signet ring, the narrow part being in 
 front. The arytenoid cartilages, much smaller than these, and of a py¬ 
 ramidal shape, are placed one on each side on the upper posterior and 
 lateral parts of the cricoid. In other words, the cricoid serves as a 
 base on which the thyroid and the two arytenoides execute the motions 
 by which the glottis is contracted or enlarged. The epiglottis, resembling 
 the leaf of an artichoke, is attached by its base to the upper and fore part 
 of the thyroid, and hangs backward over the glottis, which it closes in 
 the act of swallowing. 
 
 These cartilages are connected with each other by ligaments, the most 
 important and interesting of which are the thyro-arytenoid, which stretch 
 from the base of the arytenoid cartilages to the angle between the wings 
 
27 
 
 of the thyroid; these constitute the vocal chords, and the aperture be¬ 
 tween them named the glottis, as already stated, is the point where the 
 breath is vocalized, or rendered not only sonorous but also modulated in 
 its pitch. In the adult male the length of this fissure is from ten to eleven 
 lines, and it is from two to three lines wide where the width is greatest. 
 The dimensions are much less, however, in the female and in boys prior 
 to puberty, bearing the proportion of 3:2. This is owing to the larynx 
 of men being much larger and forming a more acute angle anteriorly. 
 The different pitch observable in the male and female voice, and in boys 
 is due to these variations. At puberty the larynx of boys is increased in 
 size and changed in form, and the voice is altered. No change, however, 
 takes place in the voice of eunuchs from whom the testes have been re¬ 
 moved before puberty. The unsteady, bleating, and weak tone observ¬ 
 able in the voice of old persons, is due to ossification of the cartilages 
 of the larynx, an altered condition of the vocal chords, and loss of 
 nervous and muscular power. 
 
 That the voice is produced in the larynx may be readily demonstrated 
 by making an opening in the trachea or the larynx below the glottis in 
 animals; this at once diverts the current of air passing from the lungs, so 
 as to completely destroy the voice; closure of the opening, however, by 
 forcing the air through the proper channels, restores it. If the opening 
 is made above the glottis in man, as sometimes occurs in unsuccessful 
 suicidal efforts at cutting the throat, the speech is lost but not the voice. 
 Again, by blowing with the bellows a current of air through the tracheal 
 end of the larynx of a slaughtered animal, vocal sounds can be produced, 
 which may be varied by changing the tension of the chords. 
 
 The preceding and other analogous facts afford data for assuming that 
 the vocal ligaments may be properly regarded as the organs of voice. 
 In a quiescent state they do not lie parallel to each other, but for the 
 purpose of respiration the aperture of the glottis is widely open and 
 somewhat triangular in shape, the base of the triangle corresponding 
 to the space between the separated arytenoid cartilages; the relative 
 position of the chords, as well as their tension, however, can be varied 
 to a considerable extent through the mobility of the thyroid and aryte¬ 
 noid cartilages. When, for instance, a vocal sound is made, the action 
 commences with the contraction of certain intrinsic muscles, the crico¬ 
 thyroid, by which the vocal chords are stretched and made tense, while 
 they are brought close to each other, and in a parallel direction, so as to 
 reduce the aperture of the glottis to a mere linear fissure, by the crico- 
 arytenoideus lateralis and arytenoideus aeting upon and approximating 
 the arytenoid cartilages. The air, driven by a forcible expiration through 
 this narrow fissure, not only causes the vocal chords to vibrate, but is 
 
'28 
 
 itself thrown into vibrations, and thus the sound required is produced. 
 As antagonists to the muscles named above, the thyy'o-arytenoideus re¬ 
 laxes the vocal chords, and the crico-arytenoideus posticus, by separating 
 the arytenoid cartilages, opens the glottis. By such an arrangement as 
 this in the muscles of the larynx, and the mobility of the cartilages, it is sus¬ 
 ceptible of an infinite number of changes in form, and capable of producing 
 the finest modulations in the voice. The tone, pitch, and intensity of the dif¬ 
 ferent vocal sounds vary with the force of the expiratory effort, the con¬ 
 formation of the larynx, and the degree of tension which is given to the 
 vocal chords'. The greater the tension of the latter, the more frequent 
 will be their vibrations, and the higher the pitch, or the more acute the 
 sound; while a less degree of tension of the chords and a wider opening 
 of the glottis will produce a grave and deeper note. For the production 
 of the deeper notes the vocal ligaments are so much relaxed that when at 
 rest they are wrinkled, but they become stretched by the current of air, 
 and thus acquire the degree of tension necessary for vibration. 
 
 The force of the voice in man depends greatly on the capacity of the 
 lungs and the volume of air which may be expelled from them in a single 
 expiration. This is a point which claims special attention from those 
 who are compelled to speak in public; for much of the discomfort which 
 audiences endure in listening to some speakers is owing to the fact that 
 in place of the voice being formed by a steady and uninterrupted current 
 of air welling up in expiration, from lungs which were filled to their ut¬ 
 most capacity in inspiration, it is produced by the feeble expiration from 
 organs but half inflated, in this way straining the vocal apparatus of the 
 speaker and trying the patience of his auditory. Ignorance of this fact 
 is the most prolific cause of so many clerical gentlemen suffering from 
 laryngitis, or clergymen's sore-throat. Medical and other teachers often 
 speak for a greater number of hours each week, and yet one seldom if 
 ever hears of their being afflicted in this way, and the same is true of 
 lawyers at the bar, and the majority of public speakers. 
 
 Such being the mode in which vocal sounds are produced in the larynx, 
 the next step will be to consider the modifications they undergo in pass¬ 
 ing through the cavities of the pharynx, mouth, and nose, by which they 
 become not merely vocal but articulate sounds, and constitute the elements 
 of speech. 
 
 The voice, formed by the passage of the air through the glottis, ac¬ 
 quires additional force and intensity, and becomes much more sonorous 
 by the reverberations of the sound in the mouth and nasal cavities and 
 the sinuses with which they communicate. When these cavities are 
 closed by coryza, or the presence of a polypus, or the growth of other 
 tumors, the voice is sensibly weakened and^ affected, so that it is said to 
 
29 
 
 be nasal, though in truth it is not, for it suffers from want of the modi¬ 
 fications which it should receive in the cavities connected with the 
 nose. The roof of the mouth, formed by the hard and soft palate, 
 serves as a sounding-board, on which the voice impinges, and is then 
 driven from the mouth. (See Fig. 1.) When the palate is broad and 
 shallow, the teeth regular and well formed, as in this skull, (see figure 
 at page 24,)^ and the mouth large, there is nothing to obstruct the 
 
 Fig. 1. 
 
 passage of the voice, and under such circumstances it is generally clear 
 and distinct, for upon the principle recognized in physics, that the angle 
 of reflection is equal to the angle of incidence, the voice, as it wells 
 up from th’e pharynx, constituting the incident wave of sound, strikes 
 upon the palate, and the reflected wave meeting with no impediment, is 
 driven directly from the mouth. When the palate is very high, narrow, 
 and angular, and the teeth irregular, as in this skull, (Fig>2,) the voice, 
 of necessity, is materially affected. .For here again applying the principles 
 already referred to, the incident wave of sound impinging upon a high, 
 narrow, and angular palate, is of course reflected, but in place of passing 
 freely from the mouth it either strikes upon the alveolus or the palatine 
 surfaces of the front teeth, and is then driven back to the pharynx. The 
 resulting sound arising from this is of the most indistinct, mufiled, and 
 cavernous character, and almost unfits a person so constituted from public 
 
30 
 
 speaking. The impediment which Demosthenes is said to have conquered 
 was slight in comparison with it. The application of the principles just 
 made no doubt has suggested itself to the minds of others, but I have 
 never heard it expressed or met with it anywhere. It is advanced for what 
 it is worth, and without any pretentious claims to originality, as an idea 
 which would naturally suggest itself to any thinking mind after observing 
 the different conformation of the parts. The most distressing cases to 
 speakers and listeners are those unfortunate persons who, either from 
 congenital deficiencies or as the result of tertiary syphilis, have an open- 
 
 Fig. 2. 
 
 ing through the hard and soft ♦palate. Thanks, however, to the applica¬ 
 tion and ingenuity of Dr. Kingsley, of New York, this defect can now 
 be readily obviated, and the speech made clear and distinct. 
 
 Speech, or articulated sound, as we have already seen, is a gift pecu¬ 
 liar to man, and is the result of education and imitation. -Division of 
 these sounds has been made, on account of their origin and variations, 
 into vowels and consonants. They are accomplished by the soft and 
 hard palates,-^he teeth, tongue, lips, and cheeks, and it is important that 
 these should be in a perfect condition to insure distinct articulation. 
 
 The vowels, A, E, I, 0, XJ, are continued sounds, which the voice fur¬ 
 nishes almost completely formed; as they need for their articulation little 
 more than opening the mouth, at varying distances, by the separation of 
 the jaws and lips, a slight elevation or depression of the tongue accom¬ 
 panying this in the pronunciation of some of the vowels. 
 
 The consonants, as their name indicates, serve to unite together the 
 
31 
 
 vowels. Their pronunciation, affected by interruptions to the passage of 
 the air in some parts of the oral cavity, by various and complicated mo¬ 
 tions of the lips and tongue, the latter of which, when applied to the palate 
 or teeth, narrow or close the channel for its exit, is always less natural 
 and more difficult than the vowels. The most harmonious languages, 
 and the most pleasing to the ear, are those which use the fewest conso¬ 
 nants and the most vowels. The division of the letters of the alphabet 
 into vowels and consonants, has not been thought sufficient; but the 
 consonants have been further distinguished according to the parts which 
 are more especially engaged in the mechanism of their pronunciation, 
 by the epithets dental, lingual, labial, nasal, and guttural. The special 
 consideration of the exact action of the velum, tongue, and lips in the 
 pronunciation of the different vowels and consonants, would involve more 
 time than we have at our command at present; it is a subject, how¬ 
 ever, worthy of careful study on the part of the dental practitioner, and 
 intimacy with it must impress upon him the importance and necessity of 
 exercising the greatest care to so conduct his operations, whether upon 
 the natural teeth or in the construction of artificial substitutes, as not 
 to mar the speech of his patient. This would be unfortunate under any 
 circumstances, but when occurring to one who is constantly compelled 
 to speak or sing in public, the importance of the modification becomes 
 immeasurably magnified. For while the improper use of the file, the in¬ 
 excusable loss of a tooth, or an imperfectly constructed and badly-fitting 
 operation, may not entirely unfit an orator, an actor, or singer, from the 
 discharge of his duties, it is calculated to produce a modification in the 
 speech not only perceptible to the auditory, but the recognition of that 
 fact reacting upon the mind of the person, unfits him for the fullest 
 development of his vocal powers. 
 
 In conclusion, it remains for us to consider the teeth in their relation 
 
 to— 
 
 Appearance.— This section of the subject more frequently attracts at¬ 
 tention and excites comment on the part of ordinary observers than the 
 portions already discussed, for even those who fail to recognize the im¬ 
 portance of the teeth as masticatory organs, or who from physical im¬ 
 perfections in the auditory apparatus, or the existence of mental defects 
 which render them incapable of distinguishing variations in sound, as a 
 general thing at least readily notice any deviation from the ordinary ap¬ 
 pearance of the teeth. And no single feature of the face is more capable 
 of changing the entire expression than the teeth. This is markedly evi¬ 
 dent when a classic face, which in repose excites admiration on account 
 of the symmetry and regularity of the features and the purity of the skin, 
 has not only the illusion dispelled at once, but a feeling of loathing in- 
 
32 
 
 duced, by a smile revealing, in place of pearls, blackened and crumbling 
 snags; while, on the other hand, a very ordinary and homely face when 
 lighted up by a smile which uncovers clean, white, regular, and symmetri¬ 
 cal teeth, becomes pleasing and attractive. 
 
 It is said that the teeth of Americans are more frail, and that the preva¬ 
 lence of dental caries, and, as a consequence, disfigured mouths, is more 
 common with us than with Europeans and people in other parts of the 
 world. Writers generally, in and out of the dental profession, appear 
 disposed to adopt this as an unquestioned fact; for my own part, however, 
 I am somewhat inclined to doubt the accuracy of this conclusion, for per¬ 
 sons whose intelligence, keen perceptions, and clear judgment can be re¬ 
 lied on, have informed me that when traveling through Europe they have 
 paid special attention to this matter, and have found the teeth of the in¬ 
 habitants of the countries through which they passed not merely as bad,- 
 but a great deal worse than Americans, for they do not pay that atten¬ 
 tion to the preservation, or restoration of the organs which is so universal 
 with us. 
 
 Again, it is asserted, as an evidence of the physical degeneracy of our 
 times, that the teeth of the present day are greatly inferior to those of 
 preceding generations. This, however, is an open question, as the opinion 
 merely rests upon suppositions and not reliable data. It is inferred, for 
 instance, because hale and hearty parents and grandparents who have at¬ 
 tained to a green old age, and retaining their teeth, in keeping with the 
 general physical conformation, that all, or a vast majority of the teeth of 
 the generations to which they belonged, were equally as good. It is 
 much more reasonable, however, to believe that the same physical weak¬ 
 ness and the operation of external influences which shortened the lives of 
 millions who were born at the same period, produced the same effects 
 upon the teeth of these millions, as we notice in those of our own day. 
 
 Unfortunately we have no exact data to go upon, so far as the univer¬ 
 sality of dental caries is concerned in the past; but the testimony of 
 Shakspeare, that 
 
 “-there was never yet philosopher 
 
 That could endure the toothache patiently,” 
 
 proves that it has prevailed to a greater or less extent in all time. With 
 regard to preceding generations in our country, we have the testimony of 
 Moore, who, in giving a description of a party with whom he traveled 
 through Yirginia in 1802, says of one of them :— 
 
 “What a pity, blooming girl, 
 
 That lips, so ready for a lover, 
 
 Should not beneath their ruby casket cover 
 One tooth of pearl I 
 
 But, like a rose by the church-yard-stone, 
 
 Be doom d to blush o’er many a mouldering bonel” 
 
33 
 
 And then adds in a foot-note, ‘'Polygnotus was the first painter, says 
 Pliny, who showed the teeth in his portraits. He would scarcely, I think, 
 have been tempted to such an innovation in America.” 
 
 How much of this statement is to be relied upon as truthful of that 
 period, and what allowance is to be made for the imagination of the poet, 
 and the disposition to satirize a people whom he neither understood nor 
 admired, is now difficult to determine. In whatever way we accept the 
 testimony, it is at least evident that our teeth have not become worse; 
 but, on the contrary, it is rather to be hoped that on account of the atten¬ 
 tion which they now receive in contrast to a former period, when there 
 were few if any skillful dental practitioners, that they have rather im¬ 
 proved than otherwise. 
 
 To whatever extent dental caries may prevail within our own country or 
 elsewhere, there is no face, however beautiful or homely, that is not more or 
 less affected by the condition of the teeth; to this end therefore it is import¬ 
 ant that irregularities of the teeth should be corrected, if no other reasons 
 existed in favor of such efforts; and that every exertion should be put 
 forth to save the natural organs when affected by decay. For to do this 
 is the highest order of surgery, and in all, but very rare and exceptional 
 cases, artificial substitutes, however perfectly constructed, fail to entirely 
 restore the lost expression. It is not enough, however, to merely save 
 the teeth, but the aim should be to preserve, so far as it is possible, the 
 natural form and size of the organs, and to so conduct, and construct the 
 operations as to make the least possible exhibition of them when the 
 patient opens his mouth. However gratifying it may be to the pride of 
 a dentist to have his work made evident to all men in this way, if an 
 operation or a series of operations have been accomplished at an unneces¬ 
 sary and unjustifiable loss of the anatomical characteristics of the teeth 
 and a great part of their utility as masticatory organs, the work, however 
 beautiful to look upon as a mere piece of handicraft, cannot be regarded 
 as in the fullest sense a complete success, or as a course which should be 
 commended or adopted by others. There are cases in which the opera¬ 
 tions, on account of the extensive ravages of decay and the portion of the 
 tooth affected, must show. To these, of course, the remark just made has 
 no reference. 
 
 The general appearance of the face is not merely affected by the con¬ 
 dition, presence, or absence of the front teeth, but the hollow, sunken cheek 
 reveals in the most unmistakable manner the loss of bicuspids and mo¬ 
 lars. The symmetry of the face in this way is frequently destroyed by the 
 inexcusable extraction of these teeth because a proper valuation is not 
 placed upon them as masticatery organs, and on the score of appearance, 
 by practitioners and patients, it being supposed that, as back teeth, their 
 
34 
 
 absence will never be noticed. As an illustration of the effect sometimes 
 produced by the adoption of such a course, observe this skull, in which you 
 see that the orbit, the malar, and superior maxillary bones on the left side 
 are very much depressed or lowered in comparison with the right side; 
 and this, beyond a question of doubt, is due to the extraction of the left 
 inferior molars, and must have given a very singular expression to the 
 person during life. There are very few faces, when examined critically, 
 in which both sides will be found symmetrical, or in harmony with each 
 other. One side, for instance, will be round and full, and the other hol¬ 
 low and sunken; after making every allowance for congenital defects, 
 falls, blows, and other accidents, in the majority of these cases the vari¬ 
 ation or deformity, for it often amounts to that, has been caused by the 
 loss of molars and bicuspids, many of which might have been saved if 
 their true value had been duly appreciated. 
 
 In the introduction of artificial teeth, the greatest care of course should 
 be exercised to preserve or restore the natural appearance of the face. To 
 do this with any prospect of success, however, it is important that the 
 anatomy and physiology of expression should be made a careful object of 
 study. 
 
 It is important, for instance, that the teeth should be so arranged as 
 not to give a sunken appearance to the mouth, or to make it so promi¬ 
 nent as to obliterate the groove or depression in the middle of the upper 
 lip; the concavity which naturally belongs to the space between the lower 
 lip and chin; and the lines which the action of the muscles create on each 
 side of the mouth, extending from the wings of the nose to the corners of 
 the lips. 
 
* V'