576 THE BLOOD-VASCULAR SYSTEM 



(anastomotica magna); and (4) the terminal branches — the radial and ulnar 

 arteries. 



(1) The Profunda Artery 



The profunda brachii (superior profunda) is the largest branch of the brachial. 

 It arises from the medial and hinder aspect of that artery, a little below the in- 

 ferior border of the tendon of the teres major. It at first lies to the medial side 

 of the brachial, but soon passes behind that vessel, and, sinking between the 

 medial and long heads of the triceps with the radial (musculo-spiral) nerve, curves 

 around the humerus in the groove for the nerve, lying in contact with the bone 

 between the medial and lateral heads of the triceps. On reaching the lateral 

 supracondyloid ridge of the humerus it perforates the lateral intermuscular 

 septum, and, continuing forward between the brachio-radialis and brachialis to 

 the front of the lateral epicondyle, ends by anastomosing with the radial re- 

 current artery (figs. 468 and 474). 



It gives off the following branches: — 



(o) The deltoid branch [r. deltoideus] which may also arise from the brachial itseK or from 

 the superior ulnar collateral. It runs across the anterior surface of the humerus, under cover 

 of the coraco-brachialis and biceps, and supplies the brachialis and deltoid. 



(6) The middle collateral artery [a. collaterahs media] runs in the substance of the middle 

 head of the triceps as far as the elbow, where it terminates in the articular rete. 



(c) The radial collateral artery [a. collaterahs radialis] arises about the middle of the upper 

 arm, and runs behind the lateral intermuscular septum to the rete at the elbow-joint. 



(d) A nutrient humeral artery [a. nutritia humeri], which may come from the brachial 

 itself or from a muscular branch, enters a canal in the humerus, 



(2) The Superior Ulnar Collateral Artery 



The superior ulnar collateral artery [a. collaterahs ulnaris superior] (inferior 

 profunda) arises from the medial side of the brachial, usually about the level of 

 the insertion of the coraco-brachiahs, at times as a common trunk with the 

 profunda. It passes with the ulnar nerve medially and downward through the 

 medial intermuscular septum, and then along the medial head of the triceps to the 

 back of the medial epicondyle, where, under cover of the deep fascia and the 

 origin of the flexor carpi ulnaris from the olecranon and medial epicondyle, it 

 enters into the anastomoses around the elbow-joint. It frequently supplies the 

 nutrient artery to the humerus. It gives branches to the triceps, to the elbow- 

 joint, and a branch which passes in front of the medial epicondyle to anastomose 

 with the anterior ulnar recurrent. 



(3) The Inferior Ulnar Collateral Artery 



The inferior ulnar collateral artery [a. collaterahs ulnaris inferior] or anasto- 

 motica magna arises from the medial side of the brachial, about 5 cm. (2 in.) above 

 its bifurcation into the radial and ulnar arteries, and, running medially and down- 

 ward across the brachialis, divides into two branches, a posterior and an anterior. 

 The posterior pierces the medial intermuscular septum, winds round the medial 

 condyloid ridge of the humerus, and pierces the triceps, between which and the 

 bone it anastomoses with the articular branch of the profunda artery, and to a 

 lesser extent with the interosseous recurrent, forming an arterial arch or rete 

 around the upper border of the olecranon fossa. The anterior branch passes 

 medially and downward between the brachialis and pronator teres, and anas- 

 tomoses in front of the medial epicondyle, but beneath the pronator teres, with 

 the anterior ulnar recurrent. From tiiis branch a small vessel passes down behind 

 the medial epicondyle to anastomose with the posterior ulnar recurrent and 

 superior ulnar collateral arteries (fig. 474). 



THE ULNAR ARTERY 



The ulnar artery [a. ulnaris] (fig. 470) the larger of the two terminal branches 

 of the brachial, begins opposite the lower border of the head of the radius in the 

 middle line of the forearm. Thence through the upper half of the forearm it runs 



