Coexistence of a pectoralis quartus muscle, a supernumerary head of biceps brachii muscle and an accessory head of flexor digitorum profundus muscle

Abstract

Although anatomical variations in the upper limb are frequent, coexistence of multiple combined variations is rare. During a routine educational dissection at Jeju National University Medical School, three muscular variations were found in a 75-year-old Korean male cadaver, in which a supraclavicular cephalic vein was also found in ipsilateral upper extremity during skinning (Go et al., 2017). Here we describe characteristics of the pectoralis quartus muscle, the supernumerary head of biceps brachii muscle and an accessory head of flexor digitorum profundus muscle, and discuss their coexistence from morphological and embryological points of view.

Anatomical Variations of the Pectoralis Major Muscle: Notes on Their Impact on Pectoral Nerve Innervation Patterns and Discussion on Their Clinical Relevance

“…The example of accessory pectoral muscles which are occasionally present may be pectoralis quartus, pectoralis intermedius, pectoralis minimus, or chondroepitrochlearis [2, 18, 20, 30]. Coexistence of a pectoralis quartus muscle, a supernumerary head of biceps brachii muscle, and an accessory head of flexor digitorum profundus muscle was reported by Song et al [38]. The presence of supernumerary muscles may potentially affect the surgical procedures.…”

Unilateral Pectoralis Quartus Muscle – A Case Report

“…The origin (thoracic attachment) of the PQ is fairly constant, as most case reports describe the muscle's origin from the costochondral junction of the 5 th and 6 th ribs [5]. There have been reports, such as ours, of PQ originating from the anterior wall of the rectus sheath [4,10]. The muscle insertion (upper limb attachment), however, shows much more variability.…”

“…The muscle insertion (upper limb attachment), however, shows much more variability. Usually, the PQ runs superolaterally from its origin, crosses the axilla anteriorly and has been reported to attach to the PMa fascia [6], the lateral lip of the intertubercular groove and the tendon of the short head of biceps brachii [1] or the coracobrachialis fascia [10,11].…”

Morphologic and morphometric characteristics of the adductor minimus in Korean: its topographic relationship with respect to neighbouring anatomical structure and clinical significance

“…Various SMs are frequently found in the upper and lower limbs, thoracic wall, neck, face, and eye, which include three-headed biceps brachii [41], pronator teres accessories [42], adductor accessories [43], pectoralis quartus [44], supernumerary digastric muscle [45], gracillimus orbitis muscle [46], and supernumerary extraocular muscle [47], with their embryologic origins also being hypothesized. The limbs first develop as the upper and lower limb buds, which are formed at levels C4-T2 and L2-S2, respectively [48].…”