The brachial artery lies in the groove between the biceps and triceps muscles. The proximal brachial artery lies medial to the humerus and moves anterior as it progresses distally. At the antecubital fossa, it runs under the aponeurosis of the biceps muscle and typically bifurcates just below the elbow into the radial and ulnar arteries (Figure 37.1).

The brachial artery is surrounded by two concomitant brachial veins, which run on either side of the artery. At the upper part of the arm, their confluence forms the axillary vein.

The profunda brachial artery is a large branch that arises from the proximal third of the brachial artery and communicates with collateral circulation to the lower arm (Figure 37.2). Due to these collaterals, the lower arm may have adequate perfusion despite injury to the distal two thirds of the brachial artery.

The basilic vein courses in the subcutaneous tissue in the medial aspect of the lower arm. At the mid arm, it penetrates the fascia to join one of the brachial veins.

The cephalic vein is entirely in the subcutaneous tissues, courses in the deltopectoral groove, and joins the junction of the brachial and axillary veins.

In the upper arm, the median nerve courses anterolateral to the brachial artery. It then crosses over the artery and lies posteromedial to the brachial artery as they pass under the aponeurosis of the biceps muscle.

In the upper half of the arm, the ulnar nerve lies posterior to the brachial artery. In the mid arm, the nerve pierces the intermuscular septum and courses posteriorly away from the artery, behind the medial epicondyle.