THE UPPER LIMB 339 



between the outer and inner heads of that muscle. Towards the 

 lower end of the groove it divides into two terminal branches — 

 interior and posterior. The anterior branch accompanies the 

 tousculo-spiral nerv^e through the external intermuscular septum, 

 and then descends between the brachio-radialis and brachialis 

 anticus to anastomose with the radial recurrent artery. The pos- 

 terior branch descends behind the external intermuscular septum, 

 and anastomoses behind the external epicondyle with the posterior 

 interosseous recurrent, and across the back of the humerus above 

 the olecranon fossa with the anastomotica magna. Besides the 

 two terminal branches the superior profunda gives off the follow- 

 ing offsets : muscular to the triceps ; an ascending branch, which 

 passes upwards between the long and outer heads of the triceps 

 to anastomose with a branch of the posterior circmnflex ; and a 

 nutrient branch, which enters a foramen on the back of the humerus. 

 The superior profvmda may arise from the third part of the 

 axillary, and it may give off the posterior circumflex. 



The inferior profunda artery arises from the brachial about the 

 centre of the arm, or sometimes from the superior profimda. It 

 accompanies the ulnar nerve through the internal intermuscular 

 septum, and then descends with it on the inner head of the triceps 

 to the back of the internal epicondyle, where it anastomoses with 

 the anastomotica magna and posterior ulnar reciurent arteries. In 

 its course it gives muscular onsets to the triceps. 



The nutrient or medullary artery arises from the brachial opposite 

 the lower border of the insertion of the coraco-brachialis, or it may 

 come off from the inferior profunda. Its course is downwards, 

 and it enters the medullary foramen of the bone to be distributed 

 to its interior. 



; The anastomotica magna artery arises about 2 inches above the 



albow. It passes inwards on the brachialis cmticus, and divides into 



two branches — a small anterior and large posterior. The anterior 



branch descends beneath the pronator radii teres, and anastomoses 



vvith the anterior ulnar recurrent artery. The posterior branch 



)ierces the internal intermuscular septum, and then passes outwards 



)eneath the triceps, resting upon the back of the humerus above the 



olecranon fossa, where it forms an arch with the posterior branch of 



he superior profunda artery. It gives a branch to the back of the 



ntemal epicondyle. which anastomoses with the inferior profunda 



nd posterior ulnar recurrent arteries. 



Varieties. — i . The brachial artery may divide above the normal level. In 

 lost cases the vessel given off earlier than usual is the radial ; more rarely it 



the ulnar, and in these cases the interosseous trunk arises from the radial ; 

 .till more rarely the premature branch is the interosseous trunk, or a large vas 

 iberrans. The level at which a high division takes place is most frequently 

 fi the upper third of the arm, less so in the lower third, and it is of rarest 

 Iccurrence in the middle third. When two arteries are present they usually 

 e side by side in the position of the normal vessel. When a vas abejxans 

 I present it usually arises from the upper part of the brachial artery, and 



rminates below by joining, most commonly, the radial artery. 



