MYOLOGY 65 



branches, four of them stout and passing to the lateral four 

 digits, and the fifth, which is very slender, to the thumb. 



M. flexor carpi radialis (figs. 13, 14, 15, 29) is located 

 between the pronator teres and caput 1 of the flexor digi- 

 torum profundus, and has origin from the medial epicon- 

 dyle deep to the origin of the latter muscle. Its slender 

 tendon extends deep to the common tendon beneath 

 tough, overlying tissue, and is inserted onto the base of 

 metacarpus two only. 



M. pronator quadratus (fig. 29) lies deep to the 

 flexors and has origin from the distal half of the ulna. 

 The fibers pass obliquely to their insertions upon the 

 neighboring border of the radius. 



M. flexor carpi ulnaris (figs. 13, 15, 29) which is 

 single in the present genus and the largest muscle of the 

 antebrachium, has origin chiefly from the medial portion 

 of the olecranon and from the proximal two-fifths of the 

 medio-caudal border of the ulna. There is also slight 

 attachment to the medial epicondyle of the humerus. 

 Its broad tendon is inserted upon the tuberosity of the 

 pisiform bone. 



The flexors of the forearm are all supphed by the median 

 nerve. A branch of the ulnar nerve to the digitorum 

 profundus may also occur but was not demonstrated. 



Of extensors there are eight, consisting of 



Mm. extensor digitorum communis extensor carpi ulnaris 



extensor metacarpi pollicis extensor carpi radialis longus 



extensor indicis extensor carpi radialis brevis 



extensor digiti quinti supinator 



M. extensor digitorum comjnunis (figs. 13, 15, 28). 

 In Ho7nodontomys this muscle is not divisible with certainty, 

 although the tendons extending from it are with insertions 

 as in Teonoma. In the latter subgenus this muscle mass 

 is considerably more robust and upon its superficial surface 

 is easily divisible into three parts, although there is inter- 



