220 



ANATOMY. 



slide alternately backwards and forwards, and 

 vice versa, so that while one condyle advances, the 

 other moves backwards, turning the body of the 

 jaw from side to side, as in grinding the teeth. 

 The inter articular cartilages are evidently design- 

 ed for facilitating the movements of the articula- 

 tion, by adapting themselves to the different in- 

 equalities in these several motions of the jaws, 

 and for preventing any injuries from friction. This 

 joint, however well secured, is occasionally dislo- 

 cated in yawning, (Scottice, gaunting,) and by other 

 causes : when so, the patient's countenance assumes 

 a truly ludicrous appearance, and without great 

 c.uv, the operator who reduces the luxation, is 

 almost certain to have his fingers bit. 



Our limits forbid us noticing the numerous pro- 

 cesttt and cavities; suffice it, however, to state, that 

 at birth, the lower jaw bone consists of two pieces, 

 which meet at the symphysis, or middle of the 

 chin, the symphysis being a species of bony con- 

 nection, which means growing together. 



This bone has been removed by a surgical ope- 

 ration ; the whole bone has also in some cases been 

 so much destroyed by necrosis, as to drop out, and 

 more frequently portions have been separated. 

 This has been in some cases produced by the long 

 continued and improper use of mercury, especially 

 when carried the length of salivation, and an abscess 

 destroying the nutritious artery of the bone, has 

 occasioned portions to exfoliate. The efforts of 

 nature to restore these losses, is frequently aston- 

 ishing, the place of both the bone, and teeth which 

 it contained, being supplied by a hard or firm body 

 of bone capable of performing the office of both. 



The Cavities Formed by the Bones of the Face 

 and Cranium yet require to be noticed, and these 

 are, orbits, nostrils, and mouth, in the which are the 

 teeth, (which have been already described,) the 

 fauces, in the anterior part of which is the os 

 hyoides, and the cavity of hearing, situated in the 

 temporal bone; all of which have been mentioned 

 in the preceding sketch, and therefore only require 

 to be shortly noticed. 



Under the forehead and on each side of the root 

 of the nose, are situated two conoidal cavities, 

 which are called the Orbits, and in these there are 

 other smaller cavities, or depressions, which serve 

 as lodging apartments for some apparently insigni- 

 ficant but important organs, such as the lachrymal 

 gland, the lachrymal sac, a passage for the tears, &c. 

 Seven bones enter into the structure of each of 

 these orbits, viz. the frontal, maxillary, jugal, lach- 

 rymal, ethmoid, palatine and sphenoid; these serve 

 the important purposes of lodging and defending the 

 organ of sight, and its adjacent parts. The situa- 

 tion of the Nostrils need not be described, as they 

 are well known to every individual. They are 

 composed of fourteen bones, the names of which 

 need not be enumerated, as all of them have been 

 already described. The nostrils are furnished with 

 several cavities and foramina, or holes, three pair 

 of pitiutary sinuses, viz. the frontal, sphenoid and 

 maxillary, the caverns of the ethmoid labyrinth, 

 the anterior foramen of the nostrils, the nasal duct, 

 the spheno palatine foramen, and the anterior pala- 

 tine foramen. The nostrils are designed doubtless 

 to form a situation for the organs of smell, and 

 their pituitary membranes, as well as to serve for 

 speech and respiration. 



Thjj Mouth is covered laterally and anteriorly 

 in the living body, by the cheeks and lips, and 

 posteriorly it is continued into the fauces; the 



two superior maxillary bones and the palatine por- 

 tions of the palate bones, forming, on its superior 

 part, which is anteriorly closed by the teeth, already 

 described. 



The Fauces, or rather the cavity of the fauces, 

 is situated under the basis of the cranium, within 

 the superior bodies of the vertebra; and posterior 

 part of the nostrils, and is composed of ten bones, 

 all of which have been described, with the exn-p- 

 tion of the os hyoides. This cavity gives locality 

 to the fauces, larynx, pharynx, and os hyoides. 



Os Hyoides, or Os Linguale, or the Toni/ite Hone, 

 is not immediately connected with any other bone, 

 but is kept in its situation by numerous muscles 

 and ligaments, there being no less than ten mus- 

 cles attached to this small bone, which is located 

 in the fauces, between the basis of the tongue and 

 the larynx. It is connected to the styloid process 

 of the temporal bone, the scapula? or blade bone, 

 the lower jaw, and sternum, or breast bone, by the 

 various muscles, and with the larynx by ligament. 



The only other bony cavity formed by the bones 

 of the face and cranium is the Ear, for a descrip- 

 tion and plate of which we have already referred 

 to the article Ear in the Encyclopedia. Suffice it 

 here to state, that in the foetus, or new-born child, 

 the squamous and petrous portions of the temporal 

 bone, in the latter of which the organ of hearing is 

 situated, are divided by a cartilaginous substance. 

 In consequence of the bony fibres being more deli- 

 cate than in the adult, very beautiful preparations 

 of the bony organ of hearing can be made, well 

 calculated to reward all the trouble and toil of a 

 juvenile anatomist, and to strike the mind with 

 astonishment at the simple, but beautiful, organiza- 

 tion of the human ear. 



Having now briefly described the bones of the 

 cranium, and face, and some of their uses, and also 

 noticed the various cavities and their contents, we 

 shall now take a general view of the whole struc- 

 ture, external and internal. 



Looking at the heads of different nations, and 

 even at the heads of different individuals in the 

 same nation, we find a very great variety in shape, , 

 not. only in the bony cranium, but in the living 

 head, with all its membranous muscular integuments 

 and hairy envelopes. It is only, however, with 

 the bare bony cranium, that we have now to do. 

 In the generab'ty of Europeans, the shape is ob- 

 long; in the Turk and Algerine, it is round ; and in 

 the Chinese and Tartar, it is broad. The cranium 

 of the African is flattened on the forehead, and the 

 teeth and chin are extended forward. The shape 

 of the head of the Asiatic and American negro, 

 also varies considerably from the European. On 

 this subject some interesting information will be 

 found in the Encyclopedia on the varieties of 

 the human species, and there are likewise plates, 

 illustrative of the subject. Suffice it here to 

 remark, that some anatomists have attributed this 

 variety in the crania of different nations to the 

 management of the children when very young, sup- 

 posing the head of the Turk to be rounded by an 

 early use of the turban, while that of an English- 

 man is flattened by the chinstay; others are of 

 opinion that the difference of the shape is not oc- 

 casioned by any such accidental means, but by na- 

 tural causes, with which we are as yet unacquainted. 

 As this, however, is rather the province of the 

 natural historian and physiologist, than of the 

 anatomist, and as our limited space remind us 

 that we must not degress, we must now contem- 



