THE BRACHIAL PLEXUS 359 



branch and one to the muscle, also a branch to the infraspinous 

 fossa and muscle. 



BRANCHES BELOW THE CLAVICLE. The three cords give 

 off the following nerves: The outer, the musculocutaneous, 

 outer head of the median, external anterior thoracic; the inner, 

 the internal anterior thoracic, inner head of median, internal 

 and lesser internal cutaneous, and the ulnar; the posterior, 

 the musculospiral and circumflex, and subscapular. 



The anterior thoracic nerves supply the pectoral muscles. 

 The external comes off from the outer cord, crosses the axillary 

 artery, and gives a branch to the inner nerve, and ends in the 

 pectoralis major, to which it is distributed. The internal 

 comes off from the inner cord, runs forth between the artery 

 and vein, and joins the branch from the external, forming 

 a loop around the artery. It supplies the pectoralis minor, a 

 portion of it passes on through this muscle to the great pectoral, 

 completing its nerve supply. 



The subscapular: The upper (from the posterior branch of 

 the upper trunk) supplies the subscapularis at its upper part; 

 the middle or long accompanies the subscapular artery to the 

 latissimus dorsi; and the lower (from posterior cord) supplies 

 the subscapularis, entering its axillary margin, and teres major. 



The internal cutaneous (from inner cord), on the inner side 

 of the axillary artery, divides at the middle of the arm into 

 an anterior branch, crossing over or under the median basilic 

 vein, which supplies the forearm as far as the wrist, and a 

 posterior, which winds above the inner condyle to back of 

 humerus, and runs to lower part of forearm. This nerve com- 

 municates with the lesser nerve and the ulnar, and supplies 

 the skin over the biceps. 



The lesser internal cutaneous (of Wrisberg), from the inner 

 cord, runs behind and then internal to the axillary vein and 

 joins the intercostohumeral nerve. It then runs along the 

 inner side of the brachial artery, and supplies the skin as far 

 as the olecranon and internal condyle. 



The intercostohumeral bears a complementary relation, 

 in point of size, to the lesser nerve, and may even replace it 

 altogether. 



The circumflex nerve, from -the posterior cord, is at first 

 behind the axillary artery. It winds back through the space 

 bounded by the triceps, humerus, and the two teres muscles, 



