A novel bilateral distal variation of the biceps brachii.

The biceps brachii muscle is known for its anatomical variability, particularly regarding the presence of additional heads, most commonly arising proximally as third, fourth, or even fifth heads. Distal variations, however, are rarely described in the literature. In this case report, we describe a rare bilateral finding of an accessory muscle belly originating from the short head of the biceps brachii. This accessory belly gives rise to a distinct tendon and inserts distally to the main biceps tendon. Recognition of this unusual anatomical arrangement in the cubital fossa is crucial to avoid misdiagnosis, guide appropriate treatment planning, and prevent iatrogenic injury during surgical procedures involving the elbow or forearm.