Abnormal musculotendinous slip from Biceps Brachii to Pronator Teres: A Case Report

Abstract

Variations of upper limb muscles are quite commonly seen during dissection. Biceps Brachii take an edge on this, as it commonly has two or more than two sites of origin and insertion, where mode of insertion being both aponeurotic as well as tendinous. In present study, apart from common modes of insertion, an additional musculotendinous slip was seen running from the medial side of the muscle belly of Biceps Brachii to Pronator Teres and Flexor Carpi Radialis deep to the aponeurosis. The functional aspect of such insertion is also questionable as Biceps brachii being a supinator is gaining attachment to a Pronator Muscle. Presence of such abnormal musculotendinous tissue can pose a difficult situation during surgical procedures in and around cubital fossa and can also be a cause of nerve entrapment syndromes. Additional muscular slip can lead to compression of neurovascular structure around that area.

Additional Muscle Slip of Bicipital Aponeurosis and its Anomalous Relationship with the Median Cubital Vein

“…8 Similarly, Trivedi et al described a case wherein additional muscle slips originated from the belly of the BB and were connected to the FCR and PT. 9 However, in the present case, only fleshy FCR muscle fibres originated from the lateral slip of the BA, without any accompanying PT fibres. Nayak et al reported a case of BA bifurcation into a larger medial slip and a small lateral slip.…”

Anomalous Bicipital Origin of Flexor Carpi Radialis Muscle: A Cadaveric Study

“…Anatomical variations related to muscles of flexor compartment of forearm have been considered as subjects of many anatomical and radiological studies. It is not uncommon to get the variations related to FCR muscle [2][3][4][5][6][7][8]. Both congenital absence [2] and duplication in the form of two separate musculotendinous units, a FCR and a FCRB (flexor carpi radialis brevis) have been reported [4].…”

“…Previous studies have shown that FCR muscle can receive additional slips from biceps tendon, brachialis, coronoid process or anterior oblique line of radius [6]. But very few reports regarding its origin from bicipital aponeurosis has been documented in medical literature [5,7,8]. Bhat et al in 2012 [5] observed variant tendinous slip arising from undersurface of aponeurotic extension of biceps brachii near its tendo aponeurotic bifurcation splitted into two bands, one continued with pronator teres and other joined with FCR.…”

“…Reported variations regarding FCR muscle include its unusual occurrence, attachments, duplication including presence of additional belly and/or tendon and also regarding insertion pattern [2][3][4][5][6][7][8]. The aim of present study is to document variations of FCR muscle and analyze anatomical basis of possible clinical and applied entities related to such variations.…”

Entrapment neuropathies due to variations in origin and insertion of biceps brachii muscle

“…21 On every occasion when the bicipital aponeurosis is attached to pronator teres in the form of a musculotendinous extension; it ends up in a range of functional differences. 22 …”