74 



THE SKELETON OF THE CAT. 



infraspinatus, coracobrachialis, and subscapularis muscles. A 

 synovial membrane lines the capsule within and forms a sheath 

 around the biceps tendon, so that the latter does not actually 

 enter the synovial capsule. 



The elbow-joint (Figs. 52 and 53) is a ginglymus or 

 hinge-joint. The bones which enter into it are the humerus, 

 radius, and ulna. 



The capsule of the joint forms a sac, with the following 

 attachments to the bones: (i) To the humerus it is attached 

 at the proximal edge of the coronoid and radial fossae; to the 

 sides of the capitulum and trochlea distad of the two epicon- 

 dyles, and to the distal edge of the olecranon fossa. (2) To 

 the ulna it is attached at the edges of the radial and semilunar 



Fig. 52. — Ligaments of Elbow- Fig. 53. — Elbow-joint, Lateral 



JOINT, Medial Side. View. 



Fig, 52. — I, humerus; 2, ulna; 3, radius, a and b, the two medial collateral 

 ligaments. 



Fig. 53. — I, humerus; 2, radius; 3, ulna, a, dorsal collateral ligament; ^.ven- 

 tral collateral ligament; c, annular ligament. 



notches; (3) to the radius around the articular facet, two or 

 three centimeters distad of the border. Many of the muscles 

 of this region are closely attached to the capsule. 



Closely connected with the capsule of the joint are the 

 collateral ligaments. The two medial collateral ligaments 

 (Fig. 52) arise from the medial epicondyle. One {b) passes 

 distad and laterad to the interval between the radius and ulnaj 

 here it divides, one branch going to the head of the radius, 

 while the other is attached to the lateral surface of the ulna at 

 the edge of the semilunar notch. The second medial ligament 

 (^a) lies dorsad of the first; it passes to the medial surface of 

 the ulna, at the distal edge of the semilunar notch. 



