162 THE POCKET ANATOMY 



Branches above the Clavicle : 



Muscular : to the longus colli and scaleni. 



Nerve to the rhomboidei, from the 5th cervical, passes through 

 scalenus medius to the base of the scapula, then under levator 

 anguli scapulae, supplying it, and ending on the anterior 

 surface of the rhomboid muscles. 



Nerve to the subclavius, from the trunk formed by the 5th 

 and 6th cervical, passes downwards in front of the 3rd part 

 of the subclavian artery to the deep surface of the subclavius, 

 often communicates with phrenic. 



Communicating : from the 5th to join the phrenic on the 

 scalenus anticus. 



Posterior thoracic, or external respiratory nerve of Bell : 

 from 5th, 6th and yth, pierces scalenus medius and then 

 descends behind the plexus and ist part of axillary artery 

 nearly to the lower border of the serratus magnus, which it 

 supplies. 



Supra-scapular: from the union of the 5th and 6th cervical, 

 passes beneath trapezius to upper border of scapula, enters 

 supra-spinous fossa through supra-scapular notch, gives off 

 two branches to the supra-spinatus, and an articular one to 

 the shoulder-joint ; thence it passes to the infra-spinous fossa, 

 and ends in the infra-spinatus. 



Branches below the Clavicle : 



The several nerves are given off as follows : 



Outer Cord. Inner Cord. Posterior Cord. 



External anterior thoracic. Internal anterior thoracic. Subscapular. 



Musculo-cutaneous. Lesser internal cutaneous. Circumflex. 



Outer head of median. Internal cutaneous. Musculo-spiral. 



Ulnar. 



Inner head of median. 



External anterior thoracic (outer cord) : crosses over 

 axillary artery to under surface of the pectoralis major, in 

 which it communicates with internal anterior thoracic. 



Internal anterior thoracic (inner cord) : passes between 

 axillary artery and vein to the two pectoral muscles. 



Subscapular : three (posterior cord). 



Upper : the smallest, perforates upper part of subscapularis. 



Lower : ends in the teres major, having previously given a 

 filament to the subscapularis. ' 



Middle or long : runs along lower border of subscapularis 

 with the subscapular vessels to supply the latissimus dorsi. 



Circumflex (posterior cord) : passes backwards with pos- 

 terior circumflex vessels at the lower border of the sub- 

 scapularis, through quadrilateral space formed by teres major, 



