The thyrohyoid muscle is an infrahyoid muscle of the neck that is innervated by the ventral ramus of C1. The primary function of the thyrohyoid muscle is to depress and fix the hyoid bone and larynx though it may also raise the larynx when the hyoid bone is fixed.
- origin: oblique line of the thyroid cartilage
- insertion: greater horn of the hyoid bone
- innervation: branch from anterior rami of C1 spinal nerve
- action: depresses and fixes the hyoid bone and larynx; when hyoid is fixed thyrohyoid raises the larynx
The thyrohyoid is a paired broad, short muscle that originates along the oblique line on the lamina of the thyroid cartilage.
The thyrohyoid muscles pass upwards from their origin on the thyroid cartilage to insert on to the greater horn of the hyoid bone.
The thyrohyoid muscles receives its blood supply from branches of the superior thyroid artery.
The thyrohyoid muscles are innervated by a branch of the ventral ramus of C1 from the cervical plexus, which courses with the hypoglossal nerve. The nerve fibers are thus not from the hypoglossal nucleus.
The thyohyoid muscle primarily depresses and fixes the hyoid bone and underlying larynx. When the hyoid bone is fixed however contraction of the muscle raises the larynx for example when singing high pitched notes.