3o8 A MANUAL OF ANATOMY 



in front of the humerus beneath the coraco-brachialis and biceps. 

 The superior thoracic artery is above the thoracic axis, where it 

 takes a course inwards to the thoracic wall. 



The external anterior thoracic nerve pierces the costo-coracoid 

 membrane to enter the deep surface of the pectoralis m*ajor. 

 The internal anterior thoracic nerve enters the deep surface 

 of the pectoralis minor, and sends branches through it to the 

 major. The posterior thoracic nerve descends upon the inner wall, 

 resting on the serratus magnus. The intercosto-humeral nerve 

 pierces the second intercostal space, and crosses the axilla to the 

 inner side of the arm. Below this nerve, on the thoracic wall, the 

 succeeding lateral cutaneous branches of intercostal nerves pierce 

 the intercostal spaces, and the posterior branch of the lateral 

 cutaneous of the third intercostal gives a branch which crosses the 

 axilla to the inner side of the arm, communicating in its course 

 with the intercosto-humeral. The three subscapular nerves lie 

 upon the posterior wall, and supply the muscles which form it. 

 The circumflex nerve lies with the posterior circumflex artery, which 

 it accompanies in its backward course. The musculo-spiral nerve 

 descends behind the axillary artery, and eventually turns to the 

 back of the humerus, but, before doing so, it gives off its internal 

 cutaneous branch. The median nerve is upon the outer side of 

 the main artery, and the ulnar nerve is internal to it, between it 

 and the vein. The lesser internal cutaneous nerve is on the inner 

 side of the vein, and the internal cutaneous nerve is usually met with 

 partly over the line of the main artery and partly on its inner side. 



The axillary lymphatic glands are disposed in four groups. The 

 external or humeral glands lie on the outer wall, where they form a 

 chain along the axillary vein. The antero-internal or pectoral 

 glands lie along the long thoracic artery at the lot&er border of the 

 pectoralis minor, resting upon the serratus magnus. The posterior 

 or subscapular glands lie on the posterior wall along the subscapular 

 artery. The central glands are situated towards the base of the 

 space. 



Axillary Artery. — ^The axillary artery is the continuation of the 

 subclavian, and it extends from the outer border of the first rib to 

 the lower border of the teres major, where it becomes the brachial. 

 When the arm is by the side of the trunk the vessel describes a curve 

 with the convexity upwards, but, when the limb is abducted to the 

 position of a right angle to the trunk, its course is almost straight. Ir 

 the latter position of the limb its course may be indicated by a line 

 drawn from the centre of the clavicle to the inner border of tht, 

 coraco-brachialis. The artery is crossed by the pectoralis minor! 

 and is thus divided into three parts — first, second, and third. | 



First Part. — The first part extends from the outer border of thtj 

 first rib to the upper border of the pectoralis minor, and it is abon 

 I inch long. 



Relations. — Anteriorly it is covered by the skin, superficial fascia 



