English

Abstract

During routine dissection of a 65 year old male cadaver, an unusual muscle was found on the right side of the neck. The aberrant muscle had a common origin with sternothyroid. Its distal end was a fleshy belly attached to the posterior aspects of manubrium sternum and medial end of first costal cartilage. The muscle ascended in supero-lateral direction crossing anterior to the common carotid artery and ascended as a slender tendon along the anterior wall of carotid sheath. In the middle third of the neck, it was accompanied by descendens hypoglossi. The tendon merged with the anterior wall of the carotid sheath in the upper part of the neck and was not discernible as a separate entity. Along with the carotid sheath, it was inserted to the base of the skull. Developmentally, the muscle appears to be the separated fibres from stylohyoid and sternohyoid line (supra- and infra- hyoid muscles) that has lost its intermittent attachment to hyoid bone. Based on its attachments, the muscle can assist sternocleidomastoid in ipsilateral tilting of the head. As the muscle was found to be crossing in front of the common carotid artery, the contraction of this muscle could compress the artery resulting in clinical symptoms. The opposite side of the neck did not show similar muscle. We did not find similar case reported in the literature.