Bilateral accessory cleidohyoid in a human cadaver

During routine anatomical dissection of the infrahyoid region, a muscle was found bilaterally originating from the sternal end of clavicle and inserting into the hyoid bone. The muscle coursed parallel and lateral to the sternohyoid muscle. The muscle was found in the presence of an intact omohyoid, thus being classified as an accessory cleidohyoid (cleidohyoideus accessorius) muscle. While other authors have reported the presence of a unilateral cleidohyoideus accessorius muscle, to our knowledge this is the first case of a bilateral cleidohyoideus accessorius muscle in the medical literature. Anatomical variations of the infrahyoid muscles may have functional, diagnostic, surgical and pathological implications.