Hello again everyone! It’s Matt from Kenhub, and today, we will be discussing the sternothyroid. The infrahyoid muscles are a group of four muscles under the hyoid bone attaching to the sternum, larynx, and scapula. They are the omohyoid, the thyrohyoid, the sternohyoid, and the sternothyroid.
The sternothyroid muscle originates from the dorsal surface of the manubrium. It has its insertion on the oblique line of thyroid cartilage. That is why the sternothyroid is the only hyoid muscle that does not directly attach to the hyoid bone. The sternothyroid lies in close relation to the capsule of the thyroid gland.
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 with the suprahyoid muscles. They play an active role in swallowing and the movement of the larynx. The sternothyroid depresses the larynx whereas the thyrohyoid elevates it when the hyoid bone is fixed.
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