530 THE ARTERIES 



back of the lower end of the humerus immediately above the olecranon fossa. From 

 this arch or rete small twigs enter and supply the elbow-joint. 



(d) A nutrient artery is sometimes given to the upper end of the humerus. 



(e) Muscular branches to the triceps. 



Chief variations. — The superior profunda may arise (a) from the axillary artery iu common 

 with one or more branches of that vessel ; or (6) as a common trunk with the inferior profunda. 

 (c) It may give off the posterior circumflex, which then runs upwards behind the teres major to 

 reach the back of the shoulder. 



(2) The Inferior Profunda Artery 



The inferior profunda arises from the inner side of the brachial, usually about 

 the level of the insertion of the coraco-brachialis, at times as a common trunk 

 with the superior profunda. It passes with the ulnar nerve obliquely downwards 

 and inwards through the internal intermuscular septum, and then along the inner 

 head of the triceps to the back of the internal condyle where, under cover of the 

 deep fascia and the origin of the flexor carpi ulnaris from the olecranon and internal 

 condyle, it anastomoses with the posterior ulnar recurrent and anastomotica magna 

 arteries. 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 internal condyle to anastomose with the anterior ulnar recurrent. 



Chief variations. — (1) The inferior profunda may arise (a) with the superior profunda ; (b) 

 from a trunk common to several other branches of the axillary and brachial arteries. (2) It may 

 be absent, its place being taken by the anastomotica magna. 



(3) The Anastomotica Magna Artery 



The anastomotica magna arises from the inner side of the brachial, about two 

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

 wards and inwards across the brachialis anticus, divides into two branches, a posterior 

 and an anterior. The posterior })ierces the internal intermuscular septum, winds 

 round the internal condyloid ridge of the humerus, and pierces the triceps, between 

 which and the bone it anastomoses with the articular branch of the superior 

 jH'ofunda artery, and to a lesser extent with the interosseous recurrent, forming 

 an arterial arch or rete round the upper l)order of the olecranon fossa. The anterior 

 branch passes downwards and inwards lietween the brachialis anticus and pronator 

 teres, and anastomoses in front of the internal condyle, but beneath the pronator 

 teres, with the anterior ulnar recurrent. From this branch a small vessel passes 

 down behind the internal condyle to anastomose with the posterior ulnar recurrent 

 and inferior profunda arteries. 



Chief variations. — (a) The anastomotica magna may take the place of the inferior profunda. 

 (b) It may be very small, the inferior profunda taking its place. 



(4) The Nutrient Artery of the Humerus 



The nutrient artery of the humerus comes off from the brachial about the 

 level of the insertion of the coraco-brachialis, or from the inferior profunda, or 

 from one of the muscular branches. It j^asses obliquely downwards through the 

 nutrient foramen, and on entering the medullary canal of the humerus divides into 

 an ascending and a descending branch, of which the latter is the larger. 



(5) The Muscular Branches of the Brachiai. 



The muscular branches are irregidar in their number, origin, and distribution. 

 They vary from about live to eight, usually come oft" from the outer ))ai't of the 

 artery, and an^ distributed to the coraco-brachialis, bice])s, and brachialis anticus 

 muscles. The nutrient artery of the humerus frequently arises from the upper- 

 most muscular branch. 



