4 UPPER EXTREMITY. 



axilla the original upper cord lies to the outside of the artery ; 

 the original lower cord to the inside; the cord formed from 

 fascicular union, posteriorly. The plexus lies between the 

 anterior and middle scaleni, beneath the clavicle upon ist ser- 

 ration of the serratus magnus and the subscapular muscles. 

 (Has 4 brs. above, 9 below the clavicle.) Receives communi- 

 cating branches from cervical plexus, phrenic, inferior cervi- 

 cal, sympathetic ganglia. Goamu'nicans, 5th cervical to phrenic 

 on scalenus anticus. Husc'ila'rcs, to longus colli, scaleni, 

 rhomboidei and subclavius. Poste'lior thorac'folS, from 5th and 

 6th cervical to serratus magnus. Passes behind brachial 

 plexus. Supra-SCaptlla'rifl, from "outer cord" obliquely out- 

 wards beneath trapezius, to supra-spinous fossa through 

 supra-scapular notch, here giving 2 branches tosupra-spinatus 

 muscle and i to joint ; in infra-spinous fossa, 2 branches to 

 muscle, x to joint; all of these are given off ABOVE the clavi- 

 cle. Those BELOW the clavicle are : Exter'nus anto'rior thorac'icus, 

 "outer cord'* inwardly across axillary vessels to pectoralis 

 major. Inter'nufl anto'rior thorac'icUl, "inner cord" passes up be- 

 tween axillary artery and vein (sometimes perforating the 

 vein} to pectorales major and minor. Subscapula'rcs, (3) "pos- 

 terior cord" the upper to subscapular muscles ; the longer to 

 latissimus dorsi ; the lower to teres major. CiTCtUHflex'tlB, "pos- 

 terior cord", down behind axillary vessels to lower border 

 subscapularis, dividing into upper branch winding _ round 

 neck of humerus, supplying deltoideus and integument; Joiu*r 

 branch to teres minor, deltoideus and integument over pos 

 terior surface deltoid. Articula'ris, given off before division, 

 to joint. Uas'CUlfl-cuta'nOM, continuation of outer cord, perfo* 

 rates coraco-brachialis, obliquely outwards between bicepa 

 and brachialis anticus to these muscles, integument to elbow, 

 and to the joint. Anterior branch, down radial border oi 

 forearm from elbow, to wrist, supplying integument to ball oi 

 thumb; communicates with radial. Posterior branch, given 

 of middle of forearm, supplies integument to wrist, on radial 

 side; communicates with radial and external cutaneous. Ifl 

 ter'E'lB CUta'aeUB, "inner cord", down in company with bra- 

 chial artery, becoming cutaneous at middle of arm, then 

 dividing into Anterior branch, supplying integument of ulnai 

 side of arm to wrist, communicating with branch from ulnar 

 posterior branch down, on inner side of basilic vein, over inter 

 nal condyle, on posterior ulnar side of forearm to wrist 

 communicating at wrist with dorsal branch of ulnar; at elbow 

 with lesser internal cutaneous. Cuta'neuS mi'nor inter'nus, fron 



