The axillary arch is generally in the form of a thin muscular anomaly and extends between the latissimus dorsi muscle and the pectoralis major muscle. In addition, it may sometimes adhere either to the coracobrachialis muscle, biceps brachi muscle, coracoid process of scapula, or axillary fascia.

It is suggested that the axillary arch may be rudimentary phylogenetic remnants of the panniculus carnosus muscle, which is highly developed to form the pectoral group of muscles in lower mammals. In humans it has regressed because its functional importance decreased during evolution in favor of a wider upper limb mobility.

 The axillary arch typically originates from the latissimus dorsi muscle and inserts as a single muscular band into the pectoralis major muscle