360 NEUROLOGY, OR ANATOMY OF NERVOUS SYSTEM 



gives a filament to the shoulder-joint, and divides into two 

 branches, an upper and a lower. The former winds around 

 the humerus to the anterior border of the deltoid, supplying 

 it and the skin, and the latter supplies the skin over the lower 

 two-thirds of the deltoid as well as the muscle, and gives a 

 branch to the teres minor, upon which a ganglion is developed. 



The external or musculocutaneous nerve arises from the 

 outer cord opposite the lower border of the pectoralis minor, 

 and runs through the coracobrachialis and over the brachialis 

 anticus to pierce the fascia at the outer border of the bierpx, 

 a little above the elbow. It then runs behind the median 

 cephalic vein and divides into two branches, anterior and 

 posterior. 



In the arm it supplies the three muscles mentioned above, 

 & filament to the elbow-joint, and one to the humerus. 



The anterior branch crosses the radial artery at wrist and 

 joins a branch of the radial nerve and the palmar cutaneous 

 branch of the median. It supplies the skin over the radius 

 and twigs to the artery. The posterior branch descends along 

 the back of the forearm to the wrist and joins branches of the 

 radial and musculospiral nerves. 



The median nerve arises by two roots, an outer from the 

 outer cord and an inner from the inner cord, which unite in 

 front of or to the outer side of the axillary artery. It lies to 

 the outer side of the brachial artery above and crosses over 

 (or under) it to its inner side. It passes between the two heads 

 of the pronator teres, running on the flexor profundus and 

 beneath the annular ligament into the hand. At the wrist 

 it lies behind and to the ulnar side of the palmaris longus. 



BRANCHES. 1. /// the arm, none. 



2. In the forearm it supplies all the superficial flexor >////,sr/r,v 

 except the flexor carpi ulnaris; some filaments to the elbow- 

 joint; some of the filaments to the muscles may come off a 

 little above the elbow. 



The anterior interosscous nerve comes off a little below the 

 elbow and runs along the interosseous membrane with the 

 artery of that name. It supplies the flexor longus pollicis 

 and the outer half of the flexor profundus digitorum muscles, 

 between which it lies, and also the pronator quadratus, in 

 which it ends. 



The palmar cutaneous branch pierces the fascia above the 



