THE AXILLA. 



261 



of the scapula to its angle, where it anastomoses with the posterior scapular, one of 

 the terminal branches of the transverse cervical from the thyroid axis. 



Four centimetres ( I ^ in. ) from its origin the subscapular gives off the dorsalis 

 scapulce, which is as large or larger than the continuation of the artery downward. 

 The position of this artery should be borne in mind in operating. It winds around 

 the outer edge of the scapula between it and the teres minor n .scle to supply the 

 muscles posteriorly. The subscapular artery is accompanied I _ the long subscapular 

 nerve to its inner side. (The first or short subscapular nerve supplies the subscapu- 

 laris muscle, the second supplies the teres major and the third or long subscapular 

 supplies the latissimus dorsi muscle. ) 



The posterior axillary chain of lymph-nodes accompanies the subscapular artery, 

 hence it is involved in operations for their removal. The point at which the dorsalis 

 scapulae winds around the axillary border of the bone is at or just above the level of the 

 middle of the deltoid muscle and below the level of the posterior circumflex artery. 



The anterior circumflex artery is comparatively insignificant. It winds ante- 

 riorly around the surgical neck of the humerus beneath the coracobrachialis muscle 

 and both heads of the biceps and gives off an ascending bicipital branch which ascends 

 in the bicipital groove and a small descending branch to the tendon of the pectoralis 



Coracobrachialis muscle 



Median 



Axillary artery 

 Ulnar nerve 

 Internal cutaneous nerve 



FIG. 273. Ligation of the third portion of the axillary artery. 



major. As pointed out by Walsham, the anterior circumflex artery on account of 

 the closeness with which it hugs the bone may be difficult to secure if wounded in the 

 operation of resection of the humerus. 



The posterior circumflex artery is much larger than the anterior. It runs around 

 the surgical neck posteriorly, below the teres minor, above the teres major, and 

 between the long head of the triceps and the humerus. It is accompanied by the 

 circumflex (axillary) nerve and they run transversely around beneath the deltoid 

 muscle on a level with the junction of its upper and middle thirds. It is to avoid 

 wounding these two important structures that the operation of resection is done 

 anteriorly instead of posteriorly. Being covered only by the skin of the axilla and the 

 superficial and deep fascias, it can readily be compressed by pressure directed out- 

 wardly against the humerus along the inner edge of the coracobrachialis muscle. 



Relations. Posteriorly the third portion of the axillary artery lies on the sub- 

 scapularis, the latissimus dorsi, and teres major muscles, with the musculospiral and 

 circumflex (axillary) nerves between the muscles and the artery. 



Anteriorly it is covered by the skin and fascia, the pectoralis major above, and 

 deep fascia of the arm below. The inner root of the median nerve crosses it and 

 sometimes the outer vena conies. 



