THE BRACHIAL ARTERY 



573 



(a) The bicipital or ascending, which runs up the intertubercular groove to supply the long 

 tendon of the biceps and the shoulder-joint; and (6) a pectoral or descending branch, which 

 runs downward along the insertion of the pectorahs major, and supphes the tendon of that 

 muscle. The anterior circumflex artery, in consequence of its being close to the bone, is 

 sometimes diflficult to seciire in the operation for excision of the shoulder-joint. 



6. The posterior circumflex humeral artery [a. circumflexa humeri posterior] 

 (fig. 467) arises from the posterior aspect of the axillary, just below the lower 

 border of the subscapularis muscle. It passes through the quadrilateral space, 

 bounded by the teres minor above, the latissimus dorsi and teres major below, the 

 humerus laterally, and the long head of the triceps medially, and, winding round 

 the back of the humerus beneath the deltoid, breaks up under cover of that muscle 

 into a leash of branches, which for the most part enter its substance. The axillary 

 (circumflex) nerve and two vense comitantes run with it. It anastomoses with 

 the anterior circumflex, the arteries on the acromion, and the profunda artery. 



Fig. 467. — The Arteries of the Shoulder. (After Spalteholz.) 



Transverse cervical artery 



Ascending branch ! Superior transverse scapular ligament 

 Descending branch j j j Transverse scapular artery 



^^,'-- — Acromion 



• Acromial branch 



Old muscle 



Infraspinatus muscle 



Circumflex m 

 scapular artery ■>■ 

 Teres minor muscle . _ . , , 



Posterior circumflex i Triceps muscle (lateral head) 



Teres major humeral artery Xriceps muscle (long head) 

 muscle 



In addition to the leash of vessels to the deltoid, it gives off the following small branches: 

 — (o) nutrient, to the greater tuberosity of the humerus; (6) articular, to the back of the shoulder- 

 joint; (c) acromial, to the plexus on the acromion; and (d) muscular, to the teres minor and long 

 and short heads of the triceps. One or more of these branches to the triceps descend either 

 between the lateral and long head or in the substance of that muscle, to anastomose with an 

 ascending branch from the profunda artery. It is by means of this anastomosis that the 

 collateral circulation is chiefly carried on when the axillary or the brachial artery is tied between 

 the origins of the posterior circumflex and profunda arteries. 



THE BRACHIAL ARTERY 



The brachial artery [a. brachialis] (fig. 468), the continuation of the axillary, 

 extends from the lower border of the teres major to a little below the centre of the 

 crease at the bend of the elbow, where it divides, opposite the junction of the 

 head with the neck of the radius, into the radial and ulnar arteries. The artery 

 is situated at first medial to the humerus; but as it passes down the arm it gradually 

 gets in front of the bone, and at the bend of the elbow lies midway between the 

 two epicondyles. Hence, in controlling haemorrhage, the artery should be com- 

 pressed laterally against the bone in its upper third, laterally and backward in its 

 middle third, and directly backward in its lower third. Throughout the greater 

 part of its course the artery is superficial, being merely overlapped slightly on 



