Role of Axillary Arch Muscle in Neurovascular Compression: A Cadaveric Study in the Western Region of Maharashtra, India

Abstract

Introduction: The Axillary Arch Muscle (AAM), is a rare anomalous finding in the axilla also known as langer’s muscle. In the literature, it is explained as a narrow muscular slip that extends from the latissimus dorsi to the pectoralis major. Variations of this muscular anomaly have been observed. The abduction and external rotation like simulation of the arm in the cadaver suggest the possibility of neurovascular compression by the AAM. The AAM causing compression is considered an etiology of thoracic outlet syndrome by some authors. The symptoms generated by neural or vascular compression can be differentiated clinically. The purpose of this article was to compare the potential role of AAM in causing neural or vascular compression and discussion with the clinical studies which showed varied results. Aim: To find out the possible anatomy of axillary arch muscle and its relation with neurovascular structures. Materials and Methods: The descriptive cadaveric study was conducted in the Department of Anatomy at Seth G.S.M.C. and KEM hospital, Mumbai, India from November 2012 to November 2014. Study included 120 axillae of 60 embalmed cadavers (60 right and 60 left axilla). Axillary arch muscles were identified and their relations with neurovascular structure in an abducted position of the arm were noted and photographed. The simple statistical method of calculating percentages (%) of the collected data was applied to the study. Results: The dissection of the axillary region was carried out in 120 axillae which included 53 male and 7 female cadavers. The axillary arch muscles were identified in the three male axillae unilaterally. Its extent and relations with the neurovascular structure were different in all three cases. Its medial attachment was on the lateral border of latissimus dorsi, fascia over the latissimus dorsi, or the subscapularis muscle, while the lateral attachment was on fascia over coracobrachialis or biceps brachii. All the cases showed close relations with neural as well as vascular structures with the potential of causing compression in varied numbers. Conclusion: Though the existence of this muscle is rare, the findings of the present study will help clinicians, surgeons, and physiotherapists to be vigilant in diagnosing the cases with AAM amongst the individuals frequently adopting hyperabduction maneuvers in their occupations or sports thereby causing neurovascular compression.