

THE BRACHIAL ARTERY 



artery and the descending branch of the transverse cervical ; the other is continued 

 along the axillary border of the scapula, between the Teres major and minor, 

 and at the dorsal surface of the inferior angle anastomoses with the descending 

 branch of the transverse cervical. In addition to these, small branches are dis- 

 tributed to the back part of the Deltoideus and the long head of the Triceps 

 brachii, anastomosing with an ascending branch of the a. profunda brachii. 



5. The posterior humeral circumflex artery (a. circumflexa humeri posterior; pos- 

 terior circumflex artery} (Fig. 524) arises from the axillary artery at the lower border 

 of the Subscapularis, and runs backward with the axillary nerve through the quad- 

 rangular space bounded by the Subscapularis and Teres minor above, the Teres 

 major below, the long head of the Triceps brachii medially, and the surgical neck 

 of the humerus laterally. It winds around the neck of the humerus and is dis- 

 tributed to the Deltoideus and shoulder-joint, anastomosing with the anterior 

 humeral circumflex and profunda brachii. 



6. The anterior humeral circumflex artery (a. circumflexa humeri anterior; anterior 

 circumflex artery} (Fig. 524), considerably smaller than the posterior, arises nearly 

 opposite it, from the lateral side of the axillary artery. It runs horizontally, beneath 

 the Coracobrachialis and short head of the Biceps brachii, in front of the neck of 

 the humerus. On reaching the intertubercular sulcus, it gives off a branch which 

 ascends in the sulcus to supply the head of the humerus and the shoulder-joint. 

 The trunk of the vessel is then continued onward beneath the long head of the 

 Biceps brachii and the Deltoideus, and anastomoses with the posterior humeral 

 circumflex artery. 



Peculiarities. The branches of the axillary artery vary considerably in different subjects. 

 Occasionally the subscapular, humeral circumflex, and profunda arteries arise from a common 

 trunk, and when this occurs the branches of the brachial plexus surround this trunk instead of 

 the main vessel. Sometimes the axillary artery divides into the radial and ulnar arteries, and 

 occasionally it gives origin to the volar interosseous artery of the forearm. 



The Brachial Artery (A. Brachialis) (Fig. 525). 



The brachial artery commences at the lower margin of the tendon of the Teres 

 major, and, passing down the arm, ends about 1 cm. below the bend of the elbow, 

 where it divides into the radial and ulnar arteries. At first the brachial artery lies 

 medial to the humerus; but as it runs down the arm it gradually gets in front of 

 the bone, and at the bend of the elbow it lies midway between its two epicondyles. 



Relations. The artery is superficial throughout its entire extent, being covered, in front, 

 by the integument and the superficial and deep fasciae; the lacertus fibrosus (bicipital fascia) 

 lies in front of it opposite the elbow and separates it from the vena mediana cubiti; the median 

 nerve crosses from its lateral to its medial side opposite the insertion of the Coracobrachialis. 

 Behind, it is separated from the long head of the Triceps brachii by the radial nerve and a. pro- 

 funda brachii. It then lies upon the medial head of the Triceps brachii, next upon the insertion 

 of the Coracobrachialis, and lastly on the Brachialis. Laterally, it is in relation above with the 

 median nerve and the Coracobrachialis, below with the Biceps brachii, the two muscles over- 

 lapping the artery to a considerable extent. Medially, its upper half is in relation with the medial 

 antibrachial cutaneous and ulnar nerves, its lower half with the median nerve. The basilic vein 

 lies on its medial side, but is separated from it in the lower part of the arm by the deep fascia. 

 The artery is accompanied by two venae comitantes, which h'e in close contact with it, and are 

 connected together at intervals by short transverse branches. 



The Anticubital Fossa. At the bend of the elbow the brachial artery sinks 

 deeply into a triangular interval, the anticubital fossa. The base of the triangle 

 is directed upward, and is represented by a line connecting the two epicondyles 

 of the humerus; the sides are formed by the medial edge of the Brachioradialis 

 and the lateral margin of the Pronator teres; the floor is formed by the Brachialis 

 and Supinator. This space contains the brachial artery, with its accompanying 

 veins; the radial and ulnar arteries; the median and radial nerves; and the tendon 

 of the Biceps brachii. The brachial artery occupies the middle of the space, and 





