Surgical neck of the humerus

The surgical neck of the humerus is a constriction below the tubercles of the greater tubercle and lesser tubercle.

It is much more frequently fractured than the anatomical neck of the humerus. A fracture in this area is most likely to cause damage to the axillary nerve and posterior circumflex humeral artery. Damage to the axillary nerve affects function of the teres minor and deltoid muscles, resulting in loss of abduction of arm (from 15-90 degrees), weak flexion, extension, and rotation of shoulder as well as loss of sensation of the skin over a small part of the lateral shoulder.