ANATOMY IN A NUTSHELL. 99 



seventh cervical nerves. It passes inward across the axillary vessels, pierces 

 the costo-coracoid membrane and supplies the Pectoralis major. It commu- 

 nicates with the internal or deep anterior thoracic. This loop is around the 

 front and inner side of the axillary artery and branches are often given from it 

 to the Pectoralis major. 



The Internal or deep anterior thoracic nerve comes from the inner cord and 

 its fibers may be traced to the eighth cervical and first dorsal nerves. It passes 

 between the axillary artery and vein, sometimes piercing the sheath of the vein. 

 It gives a filament to a branch from the external or superficial anterior thoracic 

 then pierces the costo-coracoid membrane to supply the Pectoralis minor; after 

 passing through the substance of this muscle it supplies the Pectoralis major. 



The subscapular nerves are three in number, the upper, the middle, and 

 the lower. All are from the posterior cord, as a rule, although the upper one 

 may come from the posterior branch of the first trunk before it enters into tin- 

 posterior cord. The upper one may be traced to the fifth and sixth cervical: 

 it supplies the Subscapulars muscle. 



The middle or long subscapular may be traced to the seventh, occasionally 

 to the fifth and sixth; it supplies the Latissimus dorsi. The lower one may be 

 traced to the fifth and sixth cervical and supplies the axillary border of the Sub- 

 scapularis and the 'Feres major. The Teres major may be supplied by a separate 

 branch. 



The circumflex comes from the posterior cord in common with the musculo- 

 spiral. It is traced to the fifth, sixth, and seventh cervical nerves. It lies 

 behind the third portion of the axillary artery where it passes downward and 

 outward to the lower border of the Subscapularis muscle; it then passes through 

 the quadrilateral space with the posterior circumflex artery. This space is 

 hounded above by the Teres minor, below by the Teres major, on the outside 

 by the Humerus, and on the inside by the long head of the Triceps. It gives 

 an articular branch to the shoulder-joint which pierces the capsular ligament : 

 it then divides into a superior and inferior branch. The -ulterior branch winds 

 around the surgical neck of the humerus with the posterior circumflex vessels., 

 along the Deltoid to its anterior border, supplying the muscle and the integu- 

 ment over its lower part. The inferior branch supplies the Deltoid and Teres 

 minor. The part supplying the Teres minor has a ganglion upon it. It then 

 pierces the deep fascia to supply the integument on the lower two-thirds of the 

 posterior surface of the Deltoid and the integument over the long head of the 

 Triceps. A branch from the circumflex nerve supplies the long head ol the 

 ♦Biceps, the head of the humerus and the shoulder joint. 



The median nerve is formed by a branch from the outer cord and one from 

 the inner cord. Its fillers may be traced to the fifth, sixth, seventh and eighth 

 cervical and first dorsal nerves. This junction takes place a1 the lower border 

 of the Teres minor as a rule, although it may be almost to the elbow-joint. The 

 branch from the inner cord crosses the third pari of the axillary artery; the 

 nerve lies then to the outer side of axillary artery, passing to the distal extremity 



of the arm to pass between the two heads of the Pronator radii teres. In the 

 axilla it lies first to the outer side of the third part of the axillary artery, in the 



►When the long head ol the Biceps slips from Its normal position 11 presses on this nerve 

 and produces pain — "Glass .inn." This can be cured osteopathlcally. 



