Posterior circumflex humeral artery

Course

The posterior circumflex humeral artery emerges from the third part of the axillary artery, at the inferior border of the subscapularis muscle. From its origin, it travels posteromedially with the axillary nerve, exiting the axilla through the quadrangular space. The quadrangular space is an opening in the posterior wall of the axilla which is bounded superiorly by the inferior border of the subscapularis and teres minor muscles, laterally by the surgical neck of the humerus, medially by the long head of the triceps brachii muscle and the superior border of the teres major muscle inferiorly.

Upon exiting the axilla, the posterior circumflex humeral artery then winds around the posterior aspect of the surgical neck of the humerus giving off a descending branch. It is important to note that fractures of the proximal humerus typically occur around the surgical neck. Therefore, the posterior circumflex humeral artery along with the axillary nerve may occasionally be injured following a fracture of the proximal humerus.

Branches and supply

The posterior circumflex humeral artery typically supplies the shoulder joint, deltoid muscle, teres major muscle, teres minor muscle, and the long and lateral heads of the triceps muscle. It forms rich anastomoses with the anterior circumflex humeral artery along with the deep brachial artery (profunda brachii artery) and the acromial branches of the suprascapular and thoracoacromial arteries, which also supply the shoulder region. The descending branch of the posterior circumflex humeral artery anastomoses with the deltoid branch of the deep brachial artery.

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Anatomical variations

Variations of the posterior circumflex humeral artery are commonly associated with its origin. In about a third of people, the artery arises from a common trunk with the subscapular artery. The posterior circumflex humeral artery may also arise as a common trunk with the anterior circumflex humeral artery in about 20% of cases. Rarely, the posterior circumflex humeral artery may stem from the deep brachial artery or from the subscapular artery.