The omohyoid is a narrow, flat, relatively long infrahyoid neck muscle that depresses the hyoid bone. The omohyoid is composed of two bellies - inferior and superior. Both are continuous with each other and connect at an angle by the intermediate tendon. Overall, the muscle links the scapula with the hyoid bone.

The inferior belly arises from the superior border of the scapula. It transverses the lower anterior aspect of the posterior neck triangle and ends by transforming into the intermediate tendon behind the sternocleidomastoid. The superior belly starts at the tendon and passes almost vertically toward the hyoid bone.

The contractions of the omohyoid muscle have a direct effect on the lumen of the internal jugular vein. The intermediate tendon of the muscle is closely related to the anterior wall of the internal jugular vein, and both structures connect via the pretracheal layer of the deep cervical fascia. Therefore, the contractions of the muscle tense the carotid sheath.

And finally, the omohyoid muscle forms a few borderlines between the minor neck triangles. Its superior belly separates the carotid and muscular triangles (both are parts of the anterior neck triangle). In contrast, the inferior belly of the omohyoid divides the posterior neck triangle into the subclavian and occipital triangles.

Origin: inferior belly - superior margin of the scapula medial to the suprascapular notch, superior transverse scapular ligament (rarely); superior belly - intermediate tendon.

Insertion: inferior belly - intermediate tendon; superior belly - inferior aspect of the body of the hyoid bone.

Action: depression of the hyoid bone, elevation of the scapula; this muscle also has several more functions - it pulls the larynx downward, as well as tenses the carotid sheath and widens the lumen of the internal jugular vein.

Innervation: anterior rami of the first to third cervical spinal nerves (C1 - C3) via the ansa cervicalis. The superior belly receives fibers from the C1 spinal nerve, while the inferior belly is innervated by the C1 - C3 spinal nerves.

Blood supply: superior thyroid artery of the external carotid artery, inferior thyroid artery of the thyrocervical trunk.

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Omohyoid