The posterior circumflex humeral artery is the larger of the two circumflex humeral arteries, arising from the axillary artery. It passes posteriorly with the axillary nerve through the quadrilateral space, winds around the posterior surgical neck of the humerus, and supplies the deltoid, teres minor, long head of triceps, and the shoulder joint capsule. It anastomoses with the anterior circumflex humeral artery and the profunda brachii.
The posterior circumflex humeral artery travels with the axillary nerve through the quadrilateral space, making both structures vulnerable to quadrilateral space syndrome, where fibrous bands, hypertrophied muscles, or a posterior humeral circumflex artery aneurysm compress the contents of this space. The artery and nerve are assessed together with MR neurography and arterial duplex in overhead athletes with posterior shoulder pain and paresthesia. The artery is also at risk during posterior shoulder approaches and shoulder stabilisation procedures.
Compression of the posterior circumflex humeral artery and axillary nerve within the quadrilateral space, often by fibrous bands or hypertrophied muscles in overhead athletes, producing posterior shoulder pain, point tenderness in the quadrilateral space, and selective deltoid and teres minor weakness.
A rare cause of distal arm ischaemia and digital emboli in throwing athletes, where the posterior circumflex humeral artery develops an aneurysm at the point of repeated mechanical impingement against the posterior humeral head, requiring surgical ligation or reconstruction.
