Unilateral axillary arch with two slips entrapping neurovascular bundle in axilla and its innervation by the median nerve

Author(s): Koshy Shajan, Mohandas Rao KG*, Narendiran Krishnaswamy and Somayaji SN

Axillary arch is an additional muscle bundle of various dimensions 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 median 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 arising from the belly of latissimus dorsi and were getting inserted to the tendon of coracobrachilais and lateral lip of bicipital groove. As it passed through the axilla it divided into 2 slips, enclosing the axillary vessels and nerves related to them. The fleshy fibers of the axillary arch were innervated by 2 small twigs from the median nerve. Though the occurrence of the axillary arch is very common, axillary arch with 2 slips getting innervated by the median nerve is not been reported so far. Further, a detailed literature review was done and the surgical and clinical importance of the case was discussed.

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