An Anatomical Insight into the Morphology of the Brachialis Muscle and its Clinical Implications

Abstract

Introduction: Being the chief flexor of the elbow joint, brachialis muscle, also known as ‘work horse’ of the elbow or Portal’s muscle is one of the three muscles of the front of arm. Ascertaining the morphology of the muscle is of considerable clinical significance because infrequent mention of the pathologies like tear, rupture, tendinopathies, etc., coupled with the conflicting reports of its morphology may often leads to inaccurate diagnosis of clinical conditions pertaining to it. Aim: To study the origin of the muscle in the form of number of heads and type of fibres at origin, site and manner of insertion, mode of nerve supply and presence of accessory slips. Materials and Methods: The study was carried out in the Department of Anatomy, Parul Institute of Medical Sciences and Research, Parul University, Vadodara on the 82 upper limbs used for routine dissection of first MBBS students. After incising the skin, superficial and deep fascia of the arm and cubital fossa, the biceps was retracted to visualise the origin, insertion and nerve supply of the brachialis muscle. Results: In all 82 (100%) arms, the muscle arose by lateral superficial and medial deep heads. Deep head inserted into the coronoid process and upper part of the ulnar tuberosity by an aponeurosis. In 81 (98.8%) specimens, superficial head was inserted by round tendon on to the ulnar tuberosity distal to the deep head. In one (1.2%) specimen, fibres of the superficial head were merging with biceps tendon and inserted on to the radial tuberosity. In 75 (91.5%) arms, muscle was supplied by musculocutaneous nerve and radial nerves and in four (5%) cases by the musculocutaneous, median and Radial Nerve (RN) whereas in 3 (3.5%) case by median and radial nerves. Accessory slips were present in four (5%) specimens. Conclusion: Considerable difference in the morphology of the brachialis was found with regards to the classical picture and should be kept in mind before undertaking any surgical procedure in the arm and elbow region.