Omohyoid

The omohyoid (Latin: musculus omohyoideus) is a slender neck muscle that, together with the sternohyoid, sternothyroid and thyrohyoid muscles, is classified as the infrahyoid muscle. It is located in the anterior aspect of the neck. Therefore, it also belongs to the anterior neck muscles group. The omohyoid depresses the hyoid bone. This muscle is composed of two bellies - inferior and superior - connected by an intermediate tendon.

Origin

The inferior belly of the omohyoid originates from the upper margin of the scapula, and the superior belly originates from the intermediate tendon.

Insertion

The inferior belly of the omohyoid inserts in the intermediate tendon, while the superior belly inserts on the inferior aspect of the body of the hyoid bone.

Action

Upon activation, the omohyoid muscle depresses the hyoid bone and larynx. It also pulls the hyoid bone backward and to the side (retracts the hyoid bone). This muscle elevates the scapula. The intermediate tendon fuse together with the tissues of the carotid sheath. Therefore, the omohyoid also tenses the carotid sheath.

Innervation

The omohyoid is innervated by the anterior rami of the 1st to 3rd cervical spinal nerves (C1 - C3) via the ansa cervicalis arising from the cervical plexus.

Blood supply

The omohyoid receives arterial blood supply from the superior and inferior thyroid arteries. The first one is a branch of the external carotid artery, while the second arises from the thyrocervical trunk.