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Origins, insertions, innervation and functions of the omohyoid muscle.
Hey everyone! It’s Matt from Kenhub, and in this tutorial, we will be discussing the omohyoid muscle. The infrahyoid muscles are a group of four muscles under the hyoid bone attaching to the sternum, larynx, and scapula. They are the sternothyroid, the thyrohyoid, the sternohyoid, and the omohyoid muscle – which will be the focus of this video.
The omohyoid muscle is divided into a superior and inferior belly. The inferior belly begins at the superior border of the scapula, ascends craniomedially and merges into an intermediate tendon at the height of the lateral cervical region. This tendon is connected to the carotid sheath which surrounds the neurovascular bundle which includes the common carotid artery, internal jugular vein and vagus nerve. Distally, the muscle attaches to the body of hyoid bone.
All four infrahyoid muscles are supplied by the deep ansa cervicalis which arises from the cervical plexus. The infrahyoid muscles are responsible for the positioning of the hyoid bone along the suprahyoid muscles. They play an active role in swallowing and the movement of the larynx. More specifically, the omohyoid assists the sternohyoid and the thyrohyoid in depressing the hyoid.
The omohyoid has an additional function due to its attachment to the carotid sheath. By pulling the sheath, it maintains a low pressure in the internal jugular vein – this way, increasing the blood return from the head to the superior vena cava.
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