TBE HUMERUS. 157 



The general outline of the proximal end of the bone is approximately that of an irreg- 

 ular lozenge, the two smaller angles blunted, and one of the sides strongly indented. The 

 angles are dorsal and ventral, caudal and cephalic, while the sides face obliquely ventro- 

 cephalad, etc. 



The following descriptions should be considered in connection with what is said of the 

 parts under Fig. 46 : — 



§ 402. Caiialis Sieipitalis — The bicipital canal or groove (Fig. 30, 46, 69, 70, 75). — This 

 appears as a notch between the trt/chin and the trochiter, and is overhung more by the 

 former. Through it passes the tendon of the M. biceps on its way to the Tbcl. bicipitale 

 of the scapula (Fig. 45, A). 



§ 403. Caput Artieulare — The arthral head or anatomical head of the humerus (Fig. 

 30, 46, 68-71). — This presents a smooth convex surface which, as viewed perpendicularly 

 to the proximal end of the bone, is irregularly circular in outline. Really, however, it 

 extends upon the dorsal aspect of the bone, and is, as a whole, approximately triangular. 

 It is much larger than the Fs. glenmdea of the scapula with which it articulates, being 

 twice as long and more than half as wide again. 



§ 404. Foisa Trocliiteriand — The trochiterian fossa (Fig. 30, 68). — This is a depression 

 upon the cephalic aspect of the proximal extremity of the humerus near the tip of the 

 trochiter. Upon it is inserted the M. infraspinatus. 



§ 405. TroeJiin—Tha caudal, " inner " or " lesser " tuberosity (Fig. 3, 46, 69-73).— This 

 forms the caudal obtuse angle of the lozenge represented by the entire proximal aspect. 



Notwithstanding the objections of Hyrtl (B, 200), we have employed the names epicm- 

 dylus, epitrochlea, trochiter and troeliin, which were proposed by Cbaussier and adopted by 

 Straus-Durckheim (A, I, 513). 



§ 406. Trochiter — The cephalic, " outer " or " greater " tuberosity (Fig. 30, 46, 68, 69, 

 71, 67, 74). — The proximal border of this forms the ventro-cephalic side of the lozenge rep- 

 resented by the entire proximal end of the bone. 



THE HUMERUS (Fig. 6, 7, 30, 45, 46, 67-75, 105). 



References. — Straus-Durckheim, A, I, 511-514 ; Owen, A, II, 511 ; Humphrey, A, 

 371-377 ; Chauveau, A, 83, 84 ; Chauveau (Fleming), A, 73, 74 ; Flower, A, 239, 346 ; 

 Leyh, A ; Gray, A, 233-328 ; Quain, A, I, 85-87. 



§ 407. General Description. — This is the single bone of the 

 hracMum, the proximal segment of the arm. According to the 

 membral terminology suggested by Marsh (see § 83), it is the ce- 

 phalic 0. propodiale. Its proximal and distal ends form with the 

 scapula and with the ulna and radius the shoulder and elbow joints 

 respectively. 



In all Vertebrates excepting the "fishes," that is, in all Am- 

 phibia, Reptiles, Birds and Mammals, excepting the armless 

 Amphibia (Csecilians) and Reptiles (serpents and a few lizards), the 

 humerus is present and gives attachment to numerous and impor- 

 tant muscles. In the cat, as partly shown upon Fig. 68-71, it affords 

 origin and insertion to many muscles. 



