Accessory Subscapularis Muscle: A Case Report

Variations of the subscapularis muscle have been sparsely reported in the literature. A classification scheme is lacking and may be a contributing factor. This variation may facilitate clinical syndromes presenting with sensory and motor dysfunction of the axillary nerve distribution, and vascular dysfunction of the posterior circumflex humeral artery. Furthermore, variations of this muscle may complicate surgical approaches to the glenohumeral joint. Routine dissection of the axilla was performed during which muscle fibers arising from the anterior aspect of the subscapularis muscle were found to give rise to an independent muscle band. The muscle band was attached by an independent tendinous insertion on the lesser tubercule of the humeral head. The muscle variation formed a slip around the axillary nerve and was noted bilaterally.