Appearance of the Cleidohyoideus Muscle Combined with the Multiple Variations of the Infrahyoid Muscle

Kim, Deog Im; Kim, Ho Jeong; Park, Jae Young; Lee, Kyu Seok

Abstract

Multiple variations of the infrahyoid muscle combined with appearance of cleidohyoideus muscle were found in a Korean male cadaver (age : 82) in a routine dissection. In this case, the hyoid bone descended to the level of the upper half of the thyroid cartilage. Then, the mylohyoid, stylohyoid and geniohyoid muscles, which attach to the hyoid bone, descended to the same level. An unusual cleidohyoideus muscle attached from the superior border of the medial third of the clavicle to the hyoid bone was observed bilaterally at the superficial layer. At deeper layer, the sternohyoid muscle, which was additionally attached to the first rib as well as sternum and clavicular head, appeared bilaterally. In the same layer, the left omohyoid muscle was partially merged to the muscle mass of sternohyoid and attached to the hyoid bone. In the deepest layer, the sternothyroid muscle was attached to the medial half of the first rib. The nerves that innervated this infrahyoid muscle originated from the cervical plexus, devoid of the ansa cervicalis.