Course and Relations
The artery begins at the lower border of the pectoralis major muscle (m. pectoralis major). Initially, it lies anterior to the coracobrachialis muscle (m. coracobrachialis) and then descends along the medial bicipital sulcus on the surface of the brachialis muscle (m. brachialis) toward the cubital fossa.
Upon reaching the cubital fossa (fossa cubiti), the vascular trunk lies in the groove between the brachialis muscle and the pronator teres muscle (m. pronator teres). In this region, the vessel is securely protected by the bicipital aponeurosis (aponeurosis m. bicipitis brachii). Deep to this aponeurosis, it bifurcates into its terminal branches:
- Radial artery (a. radialis);
- Ulnar artery (a. ulnaris).
An anatomical variant known as the superficial brachial artery (a. brachialis superficialis) occurs in some individuals, where the bifurcation happens high in the arm and the main trunk takes a superficial course.
Neurovascular Bundle of the Arm
Throughout its course, the artery is accompanied by two brachial veins (vv. brachiales) and the median nerve (n. medianus). The positional relationship between the artery and the median nerve changes from proximal to distal:
- In the upper third of the arm, the nerve lies lateral to the arterial trunk.
- In the middle third, the nerve crosses anterior to the vessel.
- In lineWidth lower third, the nerve lies medial to the artery.
Branches of the Brachial Artery
Several significant collateral branches arise from the main trunk to supply the musculature, bone, and elbow joint network.
Deep Brachial Artery (a. profunda brachii) This is the largest branch, originating in the upper third from the posterolateral wall of the main trunk. It passes posteriorly, accompanying the radial nerve (n. radialis), and spirals around the posterior surface of the humerus. Its branches include:
- Deltoid branch (r. deltoideus) — passes beneath the coracobrachialis and biceps muscles to supply the deltoid and upper anterior bone.
- Nutrient arteries of the humerus (aa. nutritiae humeri) — enter nutrient foramina of the bone (may occasionally arise directly from the main trunk).
- Middle collateral artery (a. collateralis media) — descends between the medial and lateral heads of the triceps muscle, participating in the elbow anastomotic network.
- Radial collateral artery (a. collateralis radialis) — the distal continuation of the deep brachial artery, anastomosing with the radial recurrent artery.
Ulnar Collateral Arteries
- Superior ulnar collateral artery (a. collateralis ulnaris superior): arises just distal to the deep brachial artery (sometimes via a common trunk). It descends alongside the ulnar nerve (n. ulnaris) toward the medial epicondyle.
- Inferior ulnar collateral artery (a. collateralis ulnaris inferior): branches off near the cubital fossa, running inferiorly and anteriorly while piercing the medial intermuscular septum.
Participation in the Elbow Anastomotic Network
All collateral vessels of the brachial system integrate into the articular network of the elbow (rete articulare cubiti), forming robust anastomoses with forearm branches:
- a. collateralis radialis anastomoses with a. recurrens radialis;
- a. collateralis media anastomoses with a. interossea recurrens;
- a. collateralis ulnaris superior anastomoses with the posterior branch of a. recurrens ulnaris;
- a. collateralis inferior ulnaris anastomoses with the anterior branch of a. recurrens ulnaris.
Clinical Landmarks: Knowing the projection of the artery along the medial bicipital sulcus is crucial for pulse palpation and temporary hemorrhage control (compression against the humerus). In the cubital fossa, the bicipital aponeurosis protects the artery during venipuncture of the median cubital vein (v. mediana cubiti).