PHYSIOLOGY : PRACTICUM II : PLATE V. 



RIGHT ARM OF THE CAT FROM THE ULNAR (caudal or "inner") ASPECT. 

 Some of the other muscles have been removed so as to expose the BICEPS. With the left 

 arm the directions of parts are reversed. 



i, cut surface of the muscle connect- 

 ing the SCAPULA with the thorax ; 2, 

 cut surface of muscle removed to expose 

 the head of the HUMERUS : 3, LIGA- 

 MENT which crossed the groove 14) in 

 which plays the TENDON of origin of 

 the biceps ; the ligament has been divid- 

 ed and reflected ; 8, a small division of 

 the TRICEPS, the great extensor of the 

 antibrachium ; the rest of the triceps has 

 been removed ; 9, tendon of insertion 

 and distal portion of the BRACHIALIS ; 

 10, end of theOLECRANON PROCESS, 

 the "point of the elbow ;" u and 12, cut 

 surfaces of muscles ; 13, pad covering the 

 PISIFORM BONE. 



The biceps is selected as a nearly 

 typical muscle, consisting of a fusiform, 

 fleshy body or belly and two tendons, 

 the proximal, of origin, the distal, of in- 

 sertion . 



The name biceps (two-headed) refers 

 to its condition in man where there are 

 two'tendons of origin, one, the "long" 

 or glenoid, from the margin of the glen- 

 oid cavity of the scapula, the shallow 

 socket for the head of the humerus ; the 

 other, the "short" or coracoid, from the 

 tip of the coracoid process of the scap- 

 ula. With the cat only the former, the 

 "long" head, is present, but the name is 

 retained. 



The biceps is inserted upon the RA- 

 DIUS near the elbow ; in this figure the 

 point of insertion is hidden by the ulna. The brachialis (9) is inserted upon the ulnar 



Compare with the right arm as shown in Plates I and II and with the human arm. 

 Note that the hand is not only flexed (bent) somewhat at the wrist, but that the palm looks 

 in the same direction as the elbow points ; this is the condition when we place the hand, 

 palm downward on the knee, or when we get on "all fours" and is technically called PRO- 

 NATION ; it is the usual condition with quadrupeds. The cat and some others can rotate 

 the parts somewhat into the condition of SUPINATION ; we can do this freely, completely 

 and forcibly, as in turning a gimlet, cork-screw or screw-driver. In walking, the human 

 hand is commonly semi-pronated, the pollex (thumb) forward. 



