The thyrohyoid connects the thyroid cartilage to the hyoid bone and is unique among the infrahyoid muscles in being innervated by C1 fibres via the hypoglossal nerve. During swallowing, when the suprahyoid muscles fix the hyoid, the thyrohyoid elevates the larynx by pulling the thyroid cartilage toward the fixed hyoid — contributing to airway protection by bringing the larynx under the tongue. At rest it acts as an infrahyoid muscle depressing the hyoid.
| Origin | Oblique line on the thyroid cartilage lamina |
|---|---|
| Insertion | Lower border of the body and greater horn of the hyoid bone |
| Nerve Supply | C1 fibres via the hypoglossal nerve (CN XII) — same arrangement as geniohyoid |
| Blood Supply | Superior thyroid artery |
| Actions | Depresses the hyoid bone when the larynx is fixed; Elevates the larynx when the hyoid is fixed by the suprahyoid muscles |
|---|
The thyrohyoid shortens the thyroid-to-hyoid distance during laryngeal elevation, assisting the suprahyoids in rapidly tucking the larynx under the tongue base during swallowing. This movement also compresses the Epiglottis against the laryngeal inlet to assist in airway closure.
Thyrohyoid membrane ossification between the thyroid cartilage and hyoid bone produces the thyrohyoid syndrome — pain on extension of the neck and tenderness at the thyrohyoid membrane that mimics laryngeal pathology. The thyrohyoid membrane is the site of supraglottic laryngeal injection for phonation procedures and for laryngeal nerve blocks.
The thyrohyoid muscle and membrane are palpable between the thyroid cartilage notch and the hyoid bone body, assessing for tenderness and membrane integrity during examination of the anterior neck.
Membrane disruption from anterior neck trauma or blunt laryngeal impact producing voice change and anterior neck pain managed conservatively unless associated with airway compromise.
