Aberrant muscle anterior to the shoulder joint: its clinical relevance.

Thirteen shoulders of 13 cases with aberrant muscle attached to the subscapularis encountered during surgery are described. The distal part of the subscapularis was completely or incompletely covered by aberrant muscle in all cases, and the anterior circumflex vessels were covered in 3 cases. Knowledge concerning these aberrant muscles is indispensable in minimizing confusion concerning surgical anatomy and in achieving adequate exposure of the shoulder during surgery while preserving the anterior circumflex artery, which constitutes the main nutrient vessel of the humeral head.