MYOLOGY 185 



in front by the common extensor of the digits, and behind 

 by the posterior uhiar ; there these two muscles approach 

 each other so closely that from the point of view of external 

 form they seem to be nearly in contact. 



The tendon, after receiving the small fasciculus from the 

 common extensor (Fig. 75, 16), as well as a fibrous band 

 emanating from the external surface of the carpus (Fig. 75, 

 17), is situated at the external side of the tendon of the 

 anterior extensor of the phalanges, and is inserted into the 

 anterior surface of the superior extremity of the first 

 phalanx. 



This muscle extends the digit or digits into which it is 

 inserted. It also assists in the movement of extension of 

 the hand as a whole. 



Posterior Ulnar {Extensor carpi ulnaris) (Fig. 73, 11 ; 

 Fig. 74, 17 ; Fig. 75, 18). — Designated by veterinary 

 anatomists as the external flexor of the metacarpus,'^ or 

 external cubital, this muscle is situated in the posterior region 

 of the external surface of the forearm, behind the lateral 

 extensor of the phalanges. 



It arises from the epicondyle ; its fleshy body, thick but 

 flattened, is directed vertically towards the carpus, and its 

 tendon is inserted into the external part of the superior 

 extremity of the metacarpus, after having given off a 

 fibrous band, which takes its attachment on the pisiform. 



It is inserted, in the cat and the dog, into the superior 

 extremity of the fifth metacarpal ; in the pig to the external 

 metacarpal ; in the ox to the external side of the canon- 

 bone ; in the horse to the superior extremity of the external 

 rudimentary metacarpal. 



This muscle flexes the hand on the forearm, and in animals 

 in which the radio-carpal articulation permits, by its 

 formation, it inclines the hand slightly onwards — that is, 

 abducts it. 



Anconeus (Fig. 72, 17 ; Fig. y-^, 13). — We have already 

 stated (p. 174) that the anconeus is included with the triceps 



* Certain authors give it the name of ulnar extensor of the wrist. It is true 

 that in the human being this is its action ; but in quadrupeds, owing to its 

 insertion into the pisiform, it draws the hand into the position of flexion. 



