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: (1) To the humerus it is attached 
at the proximal edge of the coronoid and radial fosse; 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 
Fic. 52.._LIGAMENTS OF ELBOW- Fic. 53.—ELBOw-JOINT, LATERAL 
JOINT, MEpIAL SIDE. VIEW. 
Fig. 52.—1, humerus; 2, ulna; 3, radius. «@ and 4, the two medial collateral 
ligaments. 
Fig. 53.—1, humerus; 2, radius; 3, ulna. «, dorsal collateral ligament; 4, ven- 
tral collateral ligament; ¢, 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 (4) passes 
distad and laterad to the interval between the radius and ulna; 
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. 
