We present a case of third head of biceps brachii muscle forming a tunnel along with the muscle fibers of the medial head of triceps in the middle third of the left arm of a 65-year-old male cadaver found during routine dissection for the undergraduate students. The extra head of biceps brachii muscle was arising from the mid-shaft of the humerus and inserted to the tendon of the biceps brachii enclosing the median nerve and the brachial artery in a 3 cm long canal formed by it. This extra head of the biceps brachii is of particular interest as it may compress the median nerve and the brachial artery in the mid arm during the fexion at the elbow and supination of the forearm.
