FOREARM, WRIST, AND HAND. 



NERVES. 



Musculo-cutaneous. This divides in front of the elbow 

 into two cutaneous branches. The anterior descends on the 

 front of the outer side of the forearm to the wrist, supplying 

 the outer half of the forearm in front, and the ball of the thumb 

 and communicating with the radial. The posterior runs down- 

 ward and backward, supplying the upper three-fourths of the 

 outer side of the forearm posteriorly and communicating with 

 the musculo-spiral. [627] 



Median. Passing between the heads of the Pronator radii 

 teres this descends in the midline under the superficial mus- 

 cles, and then under the anterior annular ligament, external to 

 the digital flexor tendons, where it divides into six terminal 

 branches. [627] 



Branches in Forearm. Articular : to the elbow-joint. Mus- 

 cular: arising near the elbow, to the Pronator radii teres, 

 Flexor carpi radialis, Palmaris longus, Flexor sublimis digi- 

 torum, and often the Flexor longus pollicis and Flexor pro- 

 fundus digitorum. Anterior inter osseous : This descends with 

 the anterior interosseous artery in front of the interosseous 

 membrane and under the Pronator quadratus ; it supplies these 

 structures and also the Flexor longus pollicis, Flexor pro- 

 fundus digitorum (outer half), radius, ulna, and (terminal 

 branches) radiocarpal joint. Palmar cutaneous (inconstant): 

 arising low down this pierces the deep fascia and crosses the 

 anterior annular ligament to the palm, supplying this and 

 communicating with the ulna. [628] 



Branches in Hand. Muscular : a branch running onto the 

 ball of the thumb, to the Abductor, Flexor brevis (superficial 

 head), and Opponens pollicis. Cutaneous: There are five 

 branches, running between the flexor tendons and super- 

 ficial palmar arch; the outer three supply the sides of the 

 thumb and the radial side of the index finger; the inner two 



[175] 



