140 Anatomy of the Rabbit. 



(b) The anconaeus minimus (epitrochleoanconaeus). Origin: 

 Medial epicondyle of the humerus. Insertion: Medial 

 surface of the olecranon. 



(c) The triceps brachii. Origin in three portions: 



Caput longum (anconaeus longus) : Ventral portion of the 



axillary border of the scapula. 

 Caput laterale (anconaeus lateralis) : Greater tubercle and 



related portion of the lateral surface of the humerus. 

 Caput mediale (anconaeus medialis) : Posterior surface of the 

 humerus. 

 The three portions are practically separate muscles. Insertion on 

 the olecranon. 



B. Flexor group. The muscles arise in front of the axis of the humerus 

 and are inserted on the radius and ulna in front of the elbow-joint. 



(a) The biceps brachii. Origin: Anterior border of glenoid 

 cavity. Insertion : Ventromedial surface of the ulna and 

 medial surface of the radius. The muscle possesses only one 

 head in the rabbit. 



(b) The brachialis. Origin: Anterior and lateral surfaces of the 

 humerus, divided unequally into a larger lateral and a 

 smaller medial portion by the insertion tendons of the 

 deltoideus and abductores muscles. Insertion: In common 

 with the biceps. 



6. Muscles arising from the distal end of the humerus and the radius 

 and ulna and inserted on the hand (extensors and flexors of the hand 

 and the individual digits). The long insertion tendons pass through 

 perforations of the dorsal carpal and transverse (ventral) carpal liga- 

 ments (Fig. 47). 



A. Extensor group. The muscles have a general area of origin from 

 the lateral epicondyle of the humerus and the anterodorsal, or antero- 

 lateral surface of the radius and ulna. Insertion dorsal. 



(a) The extensor carpi radialis longus. Origin : Lateral epi- 

 condyle. Insertion: Base of the second metacarpal. 



(b) The extensor carpi radialis brevis. Origin : Lateral epi- 

 condyle. Insertion: Base of the third metacarpal. The 

 muscle is partly fused with the foregoing one, and the tendons 

 are closely associated on the wrist. 



(c) The abductor poUicis. Origin : Anterolateral surface of the 

 radius and ulna. Insertion: Base of the first metacarpal. 

 The muscle is partly concealed by (e). Its tendon forms a 

 conspicuous cross with those of (a) and (b). 



(d) The extensor poliicis et indicis. Origin: Anterolateral 

 surface of the radius and ulna. Insertion: Ungual phalanx 

 of the pollex and the head of the second metacarpal. Its 

 tendon is the first of five in the centre of the carpus. 



(e) The extensor digitorum communis. Origin: Lateral epi- 



