A rare case of bilateral sternocleidomastoid muscle variation.

An abnormal sternocleidomastoid (SCM) muscle was encountered bilaterally during routine dissection of the head and neck region of a 60 year old male cadaver. The SCM muscle of both the sides had an additional sternal head arising from the capsule of the sternoclavicular joint and the supero-lateral border of the manubrium sterni. The clinical significance of the present variation is immense, as it might cause difficulty in assessing the vital neurovascular structures of the neck during surgical procedure.