The omohyoid is a digastric muscle with two bellies and an intermediate tendon, running from the scapula around a fascial pulley on the clavicle to the hyoid bone. Its unusual two-belly anatomy with a fascial sling around the intermediate tendon allows it to change direction of pull, making it both a hyoid depressor and a fascial tensor. Surgeons encounter it as a landmark in the posterior cervical triangle and anterior neck.
| Origin | Superior border of the scapula medial to the suprascapular notch |
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| Insertion | Lower border of the hyoid bone via two bellies connected by an intermediate tendon held by a fascial sling to the clavicle |
| Nerve Supply | Ansa cervicalis (C1, C2, C3) |
| Blood Supply | Superior thyroid artery |
| Actions | Depression and retraction of the hyoid bone; Tenses the cervical fascia, reducing venous pooling in the neck during inspiration |
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By tensing the deep cervical fascia it reduces venous pressure in the jugular vein during inspiration, preventing the vein from collapsing and maintaining venous return. This fascial tensioning role is unique among the infrahyoid muscles.
The omohyoid is a key surgical landmark in neck dissection procedures, defining the boundary between the posterior and central neck compartments. Omohyoid syndrome, a rare condition in which the intermediate tendon snaps over the clavicular fascial sling, produces a visible and palpable snapping mass in the lateral neck during neck movements, sometimes confused with a carotid aneurysm or lymph node.
The posterior belly of the omohyoid is palpable crossing the posterior triangle of the neck between the sternocleidomastoid and trapezius muscles, and the anterior belly can be felt during swallowing adjacent to the thyroid cartilage.
Rare snapping of the intermediate tendon over its fascial sling producing a visible neck mass with head turning that resolves spontaneously or rarely requires surgical excision.
