A 43-year-old man has suffered an anterior dislocation of his humerus following trauma. He describes weakness in shoulder elevation and abduction, with numbness, and altered sensation over the lateral aspect of the arm

h. The axillary nerve winds around the head of the humerus. It is this tortuous course that puts it at risk from damage from trauma, e.g. from cast application or during rotator cuff surgery. It supplies the deltoid muscle and teres minor and therefore results in problems with shoulder elevation and abduction. It also provides sensation to the skin on the lateral aspect of the arm over the body of deltoid muscle.