Bilateral Three-headed Biceps Brachii Muscle and its Clinical Implications.

Biceps brachii muscle frequently exhibits variant morphology in terms of origin, insertion, and mode of innervation. Nevertheless, the three-headed biceps brachii is described to be the most common variation. During routine cadaveric dissection, we came across a unique case of tricipital biceps brachii present on both the sides and variant course and branching pattern of musculocutaneous nerve. The third-headed biceps brachii emerged from the deep investing fascia of the brachialis muscle on both the sides. The musculocutaneous nerve (MCN) did not pierce the coracobrachialis muscle on the right side and terminated by supplying the muscles of the anterior compartment of the arm. However, a normal course was pursued by the MCN on the left side. Thus, scrupulous knowledge of the variant morphology of the biceps and associated structures may facilitate preoperative diagnosis and management of the upper limb diseases and circumvent iatrogenic injuries.