The arm being abducted, the course of the brachial artery is indicated by a line drawn from the inner edge of the coracobrachialis muscle, at the junction of the anterior and middle thirds of the axilla, above, to a point just inside the tendon of the biceps at the bend of the elbow, below, midway between the two condyles of the humerus. This lies in the internal bicipital furrow along the inner edge of the biceps muscle. The artery is superficial in its entire course. It is accompanied by two small venae comites, which closely embrace it. The basilic vein runs along its inner side. The median nerve lies on the artery to its outer side above, then directly on it and a little to its inner side at the middle, and passes to its inner side at the bend of the elbow. The medial antebrachial (internal) cutaneous nerve, much smaller than the median, passes down along the inner side of the artery between it and the basilic vein to pierce the fascia about the middle of the arm (Fig. 285).

The ulnar nerve lies to the inner side of the artery above and is posterior to the basilic vein. About opposite the insertion of the coracobrachialis it diverges from the artery to pierce the internal intermuscular septum.

Relations of the Brachial Artery

In Front. Skin and fascia

Overlapped by coracobrachialis and biceps Median basilic vein Bicipital fascia Median nerve

Outer Side Median nerve, abov Coracobrachialis Biceps Vena comes cutaneous and ulnar nerves Median nerve below Basilic vein Vena comes

Brachial Artery

Inner Side Medial antebrachial (int).

Behind

Triceps (long and inner heads) Radial (musculospiral) nerve (Sup.) profunda artery Coracobrachialis muscle Brachialis anticus muscle

Branches Of The Brachial Artery

The branches of the brachial artery are the profunda (superior), the superior ulnar collateral (inferior profunda), the nutrient, muscular, and inferior ulnar collateral (anastomotica magna).

Fig. 284.   Surface anatomy of the arm.

Fig. 284. - Surface anatomy of the arm.

Not infrequently the brachial artery instead of dividing into the radial and ulnar opposite the neck of the radius divides higher up. This is called a high division and is seen most often in the upper third of the arm. The two vessels may follow the

Fig. 285.   Dissection of the arm, viewed from the inner side.

Fig. 285. - Dissection of the arm, viewed from the inner side.

Usual course in the arm, or the radial may run under the biceps tendon, instead of over it, and the ulnar may accompany the median nerve in front of the medial con dyle or the ulnar nerve behind it. 18

The profunda is given off just below the lower edge of the posterior fold of the axilla (teres major). It accompanies the radial (musculospiral) nerve around the arm to its outer side; it sends one branch, the radial collateral, to the front of the elbow and the middle collateral behind it. The superior ulnar collateral artery (inferior profunda) comes off about opposite the insertion of the coracobrachialis muscle. It is much smaller than the profunda and with the ulnar nerve pierces the internal intermuscular septum. The nutrient artery comes off close to the origin of the superior ulnar collateral (inferior profunda) or is a branch of it. It passes downward in the bone in a direction toward the elbow-joint. The inferior ulnar collateral (anastomotica magna) is given off 5 cm. (2 in.) above the elbow and passes inward over the brachialis anticus to divide into two branches, one going down in front and the other behind the elbow.

Fig. 286.   Ligation of the brachial artery in the middle of the arm showing the median nerve lying on the artery and the ulnar nerve to its inner side.

Fig. 286. - Ligation of the brachial artery in the middle of the arm showing the median nerve lying on the artery and the ulnar nerve to its inner side.