THE ANTERIOR RADIOULNAR REGION 207 



into the fascia of the forearm, flexor carpi ulnaris, pisiform, 

 scaphoid, or little finger muscles. This muscle with the central 

 part of the palmar fascia was a superficial flexor of the fingers, 

 but has been reduced by the development of the other flexors. 



4. M. flexor carpi ulnaris (M. ulnaris internus) is the inner- 

 most of the superficial group; rises by two heads, one from the 

 common tendon, and one from the inner side of the olecranon 

 and upper two-thirds of the posterior border of the ulna by 

 an aponeurosis common to it, the flexor profundus digitorum 

 and the extensor carpi ulnaris; muscular fibers end in a tendon 

 which occupies the anterior margin of the lower half of the 

 muscle; posteriorly the muscular fibers continue down to within 

 an inch of its insertion; inserted into the pisiform, by a small 

 band to the anterior annular ligament, and prolonged by the 

 pisometacarpal and pisouncinate ligaments to the fifth meta- 

 carpal and unciform. 



The ulnar nerve and posterior ulnar recurrent artery pass 

 between its two heads; the pisiform throws this tendon for- 

 ward, so that the ulnar pulse connot be felt so well as the 

 radial. 



5. M. flexor sublimis digitorum (perforatus), placed behind 

 the preceding, rises by three heads: (1) Inner condyle by 

 the common tendon, fibrous septa, and internal lateral liga- 

 ment; (2) internal margin of the coronoid; (3) anterior oblique 

 line of the radius; divided below into four parts ending in 

 tendons inserted into the mesial phalanges of the four inner 

 digits. Through the annular ligament they are placed in pairs; 

 the anterior pair are for the ring and middle fingers, the posterior 

 for the index and little fingers. In the palm they diverge and 

 enter a sheath with the flexor profundus; opposite the bases 

 of the proximal phalanges the tendon divides and folds around 

 the deep flexor, and is reunited behind it; the two portions 

 again separate and pass on each side to the middle of the lateral 

 border of the second phalanx. 



The Deep Muscles. 1. M. flexor profundus digitorum (per- 

 forans). Origin, the upper three-fourths of the inner and 

 anterior surface of the ulna, from not quite the ulnar half 

 of the interosseous membrane for the same distance, and 

 from an aponeurosis attached to the posterior border of 

 the ulna, common to it, the flexor and extensor carpi 

 ulnaris. Only one tendon (for the index finger) separates 



