Abstract

THE HIDDEN HEAD: A CASE REPORT OF AN ACCESSORY HEAD OF BICEPS BRACHII: ANATOMICAL AND CLINICAL SIGNIFICANCE

Dr. Yajnesh Darbar*, Dr. Kochuthresia Jose and Dr. Rashmi N. R.

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Abstract

Introduction: The biceps brachii muscle typically comprises two heads of origin, long and short head. However, anatomical variations such as the presence of an accessory head have been documented and may have clinical implications during surgical procedures, particularly in relation to neurovascular structures in the arm. Methods: During a routine cadaveric dissection of the left upper limb of a 58 years old male cadaver, an unusual muscular slip was observed. Detailed dissection was carried out to study the origin, insertion, course, and relation of this accessory head to adjacent neurovascular structures. Results: An accessory head of the biceps brachii was found originating from the anteromedial surface of the shaft of humerus, distal to the insertion of the coracobrachialis. It fused to form the common tendon of the muscle near the distal third of the arm and gets inserted into the radial tuberosity of the radius bone. The musculocutaneous nerve after exiting the coracobrachialis, it runs between the biceps brachii and brachialis muscles and continued its usual course without signs of entrapment or compression. Discussion: This case highlights the morphological variability of the biceps brachii muscle. The presence of an accessory head can alter the topographical anatomy of the arm, potentially affecting surgical approaches or neurovascular interventions. Awareness of such variations is essential to avoid intraoperative complications and to accurately interpret radiological images.

Keywords: Biceps brachii, third head, variation, musculocutaneous nerve.