Unusual formation of the median nerve associated with the third head of biceps brachii.

Unilateral variations in the formation of the median nerve, with the presence of the third head of the biceps brachii entrapping the nerve are very rare. These variations were observed on the right side, of a 30-year-old male cadaver during routine dissection at the Department of Human Anatomy, University of Nairobi. The median nerve was formed by the union of three contributions; two from the lateral cord and one from the medial cord. An additional head of the biceps brachii looped over the formed median nerve. On the left side, the median nerve was formed classically by single contributions from the medial and the lateral cords. These variations are clinically important because symptoms of high median nerve compression arising from similar formations are often confused with more common causes such as radiculopathy and carpal tunnel syndrome.