An unusual case of axillary arch bridging across the anterior and posterior axillary folds in the distal part of axilla

Axillary arch is an additional muscle slip extending usually from the latissimus dorsi in the posterior fold of the axilla, to the pectoralis major or other neighboring muscles and bones. In the present case presence of such unusual axillary arch innervated by the fine twigs of musculocutaneous nerve has been reported. During routine dissection of axilla region in one of the upper limbs, the occurrence of axillary arch was observed. The muscle fibers were posteriorly continuous with the belly of latissimus dorsi and anteriorly were merging with fleshy fibers of pectoralis major on its deeper surface. The fibers of the axillary arch were innervated by fine twigs from the musculocutaneous nerve. Position of the axillary arch and its critical relationship with neurovascular bundle has been discussed. Further, a detailed literature review was done and the surgical and clinical importance of the case was discussed.