The thyrohyoid has the unique distinction of being innervated by C1 fibres that travel with the hypoglossal nerve (CN XII). It is the only strap muscle to receive its innervation through a cranial nerve trunk.
| Origin | Oblique line of the thyroid cartilage |
|---|---|
| Insertion | Body and greater horn of the hyoid bone |
| Nerve Supply | C1 via the hypoglossal nerve — unique innervation by a fibre hitching a ride on CN XII |
| Blood Supply | Superior thyroid artery |
| Actions | Elevates the larynx during swallowing; Depresses the hyoid when the larynx is fixed |
|---|
The thyrohyoid's C1-via-CN XII innervation is clinically important — it is preserved in most CN XII palsy cases because the injury is typically below where the C1 fibres hitch on. The thyrohyoid membrane (between the thyroid cartilage and hyoid) contains the internal laryngeal nerve and superior laryngeal vessels — percutaneous laryngeal procedures target this membrane.
Palpated between the thyroid cartilage and hyoid bone during laryngeal elevation in swallowing.
The thyrohyoid membrane pierced percutaneously to deliver anaesthetic to the internal laryngeal nerve, suppressing the cough reflex for awake intubation.
