Deep artery of arm
The deep artery of arm (also known as arteria profunda brachii and the deep brachial artery) is a large vessel which arises from the lateral and posterior part of the brachial artery, just below the lower border of the teres major. Structure. It follows closely the radial nerve, running at first backward between the long and medial heads of the triceps brachii, then along the groove for the radial nerve (the radial sulcus), where it is covered by the lateral head of the triceps brachii, to the lateral side of the arm; there it pierces the  lateral intermuscular septum, and, descending between the brachioradialis and the brachialis to the front of the lateral epicondyle of the humerus, ends by anastomosing with the radial recurrent artery. Branches and anastomoses. It gives branches to the deltoid muscle (which, however, primarily is supplied by the posterior circumflex humeral artery) and to the muscles between which it lies; it supplies an occasional nutrient artery which enters the humerus behind the deltoid tuberosity. A branch ascends between the long and lateral heads of the triceps brachii to anastomose with the posterior humeral circumflex artery; the medial collateral artery, a branch, descends  in the middle head of the triceps brachii and assists in forming the anastomosis above the olecranon of the ulna; and, lastly, a radial collateral artery runs down behind the lateral intermuscular septum to the back of the lateral epicondyle of the humerus, where it anastomoses with the interosseous recurrent and the inferior ulnar collateral arteries.