Anomalous pectoral musculature

Abstract

Anomalous disposition of pectoral muscles was encountered in an adult female cadaver on the left side. A prominent cleft separating the sternocostal and clavicular portions of the pectoralis major was noticed. The fibers of pectoralis major were partially fused with the deltoid, resulting in obliteration of the deltopectoral groove. Interestingly, cephalic vein was seen traversing superficial to the clavicular portion of the pectoralis major and pierced it to drain into the axillary vein. The pectoralis minor was inserted mainly on the coracoid process and few fibers were found blending with the coracobrachialis and short head of biceps brachii. Further, pectoralis minimus, a rare anatomic variant, was also observed lying superior to pectoralis minor. It was innervated by a twig from the lateral pectoral nerve at its superficial surface. Awareness of possibility of such anomalous muscles is important for surgeons operating on the chest wall.

Surgical anatomy of the pectoral nerves and the pectoral musculature

“…The pectoralis minimus (sterno‐costo‐coracoidian muscle or sterno‐chondro‐coracoideus ventralis) is located superomedially with respect to the pectoralis minor (e.g., Turgut et al,2000; Soni et al,2008). It has been observed to be innervated by a branch from the LPN (Huntington,1904; Soni et al,2008).…”

“…The pectoralis minimus (sterno‐costo‐coracoidian muscle or sterno‐chondro‐coracoideus ventralis) is located superomedially with respect to the pectoralis minor (e.g., Turgut et al,2000; Soni et al,2008). It has been observed to be innervated by a branch from the LPN (Huntington,1904; Soni et al,2008). It is considered to be homolog to the sterno‐chondro‐scapularis, the antecedent form of the subclavius originating from the upper part of the deep pectoral layer, or to represent an atypical segment of the pectoralis major (Huntington,1904).…”

A cephalic vein drained into one of the double axillary veins through the pectoralis major muscle

“…There are only two similar cases of an intra-pectoral CV path: one perforated the cleft between the clavicular and sternal heads of the pectoralis major muscle and drained into the external jugular vein [7], and the other pierced the clavicular head of the pectoralis major muscle and terminated into the axillary vein [16]. However, there is no mention on the lower part of the CV in the previous reports such as appeared in this case.…”

“…The intra-pectoral path of the CV, however, has rarely been reported on to date [7,16]. In this report, we describe a rare variation of the CV that perforates the pectoralis major muscle and then enters one of the double axillary veins.…”

Oblique Pectoralis Anterior Muscle: a Rare Anatomical Variation of the Pectoral Region

“…With the presence of accessory muscle, the pectoralis major often originates lateral to the aberrant muscle instead on the edge of the sternum. However, the understanding of the anatomical variations of anterior chest wall musculature and quickly identification intraoperative variations helps to achieve the proper dissection planes during breast and chest wall surgeries [16]. However, these rare variations should be categorized as a distinct sub-type.…”