Unilateral Absence of the Sternohyoid Muscle with Contralateral Tendinous Belly of Superior Belly of Omohyoid Muscle: A Very Rare form of Infrahyoid Muscle Variation.

The sternohyoid, sternothyroid, thyrohyid and omohyoid constitute the infrahyoid group of anterior neck muscles. All these muscles are supplied by Ansa crvicalis related to the anterior wall of carotid sheath. During regular cadaveric dissection in the Department of Anatomy at AIIMS, Bhubaneswar, a case of right sided absence of sternohyoid muscle with left sided tendinous superior belly of omohyoid muscle was found. Though literature survey shows the tendinous belly (or absence) of superior belly of omohyoid muscle, but its presence in combination with absence of opposite side sternohyoid muscle is hardly reported. The omohyoid muscle has effect on intracerebral venous hemodynamics. Developing from a common muscle primodium the infrahyoid muscle group shows a number of variations. Because of increased use of Infrahyoid myocutaneous flaps for medium sized head and neck reconstruction surgery this knowledge will be helpful for handling and selecting a flap.