The internal laryngeal nerve is a branch of the vagus nerve. It forms from the division of the superior laryngeal nerve into external and internal laryngeal branches at the level of the hyoid bone.
The internal laryngeal nerve descends within the carotid sheath posterior to the internal carotid artery and then passes anteromedially at the level of thyrohyoid membrane. It pierces the thyrohyoid membrane to emerge within the laryngeal part of the pharynx in the piriform recess. From the piriform recess, the nerve fibres distribute as, according to their type:
- somatic sensory fibres from the mucosae of:
- larynx above the vocal cords
- special visceral sensory fibres that carry the sensation of taste from the region of the valleculae
The somatic sensory fibres have their cell bodies in the inferior vagal ganglion and synapse with the sensory nucleus of the trigeminal nerve within the medulla. The special visceral sensory fibres have their cell bodies in the inferior vagal ganglion and synapse in the nucleus of tractus solitarius.