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A Case Report and Proposal for the Systematization of Axillary Arch Muscles
Author(s) -
Miller Joseph M. A.,
Trelease Robert
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.896.22
Subject(s) - anatomy , medicine , axillary nerve , latissimus dorsi muscle , axilla , fascia , brachial plexus , breast cancer , cancer
A variety of axillary arch muscles have been reported with wide range of frequency of occurrence over the course of more than two centuries. Frequencies for the general incidence of axillary arch muscles have been documented in a general way, without differentiating among the variant types. Here we describe a new case of axillary arch muscle and propose a framework for classification of such muscles based on their origins, insertions, and innervations. During the dissection of the back, thorax, and axillary regions for a gross anatomy course for first year dental students, we identified a single axillary arch muscle on the left side of an 82 year old, Caucasian male cadaver. It originated from the lateral aspect of the superior lateral border of latissimus dorsi, extended through the axillary fascia, crossing anterior to the axillary sheath to insert on the superior brachial fascia, and tendon and fascicles of the deep distal aspect of the sternocostal head near its insertion. The muscle appeared to be innervated by ramifying proximal fibers of the thoracodorsal nerve. We saw no evidence of innervation by lateral or medial pectoral nerves or intercostobrachial nerve, all of which were a considerable distance from the muscle. In the literature, a wide range of axillary arch muscle variants has been variously described (a.k.a. as Langer's muscle, achselbogen muscle, and axillopectoral muscle) in an unsystematic way. We propose a classification of axillary arch muscles which categorizes these muscles into two types: Category I – latissimus dorsi origin, and Category II – non‐latissimus dorsi origin, and a number of subtypes based on insertion and innervation. Bergman et al. (1988) and other authors have noted different variants of latissimus dorsi origin arch muscles (our “Category I”) that varied in their insertion, for example, on the pectoralis major or its tendon, coracobrachialis, deep brachial fascia, with innervations including the medial or lateral pectoral nerves, thoracodorsal nerve, or intercostobrachial nerve. We provide an additional logical framework to designate these subtypes according to insertion and innervation. This classification scheme will help researchers catalog frequency of occurrence more precisely for the various types of axillary arch muscles.