94 A^'AT03IICAL TECBNOLOGY. 



of the leg, and, like its counterpart the elbow, is but slightly removed from the level 

 of the ventral border of the trunk. The ankle of the quadruped is often called hough 

 or hock. 



§ 224. Os Hyoides and Larynx — (Fig. 30). — Dependent from 

 the caudal region of tlie basis cranii is an inverted segmented 

 Ibouy and cartilaginous arch — the Os hyoides. Connected with 

 the summit or ventral end of this arch is the larynx, a cartilagi- 

 nous case forming the principal organ of the voice. (In Fig. 30 the 

 larynx is placed too nearly in contact with the fifth Yertebra cer- 

 vicalis). 



The keystone of the arch appears in Fig. 30 only Iby its sinistral 

 end, shown as a small subquadrate area close to the angle formed 

 by the junction of the ventral outlines of the head and the neck. 

 The lateral bar extending from this point caudad and slightly 

 ventrad is one of a pair of pieces called thyro-hyals, which are 

 additions to the arch itself, and are most directly connected with 

 the larynx. 



Each lateral half or pier of the arch consists of four segments, as 

 follows : — 



Next to the basihyal is the cerato-hyal. Then comes the 

 epiJiyal, and then the stylo-Tiyal. In the figure the dotted line 

 from the words os hyoides is drawn to the arthron between tlie 

 cerato-hyal and epihyal. The three pieces mentioned are bony ; 

 the fourth piece, which appears in the figure along the side of the 

 bulla, is cartilaginous, and has been called Ctl. stylo-hyoidea. It 

 is attached at the bottom of a deep pit just laterad of the bulla ;. 

 (see Fig. 57, Fs. tyh.). The sequence of the osseous segments may 

 be connected with the alphabetical order of the initials of their 

 names, B, C, E, and -S'. 



A. For fuller accounts of the OsJiyoides, and for the origin of the names of the seg- 

 ments, consult Owen, A, II., 506 ; Flower, A, 123. Straus- DuTckheim's account (A, I, 450- 

 453) is not very satisfactory. The figures of Mivart (B, 78) are good, but he ascribes to 

 the cat a small osseous segment — the tympano-7it/al—v/hich exists in the dog (Flower, A, 

 123), but which we have failed to find in even old cats, and which is not mentioned By 

 Straus-Durckheim. 



B. In man the thyro-hyals are disproportionately large, and are called the greater 

 cornua, while the cerato-byals are called lesser cornua. Quain, A, I, 55 ; Gray, A, 306 ; 

 Parker and Bettany, A, 305. 



The following parts of the larynx may be recognized in the 

 figure : — 



The largest and ventrally placed piece, and that which is reached 



