The sensory supply to the larynx is from the:

• Superior laryngeal nerve - above the vocal cords

The external laryngeal branch provides the motor supply to the cricothyroid muscle.

The internal laryngeal branch passes beneath the mucosa of the piriform fossa, and provides the sensory supply to the interior of the larynx as far as the vocal cords (Fig 1a).

Laryngoscopy may induce vagal reflexes via stimulation of the internal laryngeal nerve, which provides the sensory supply to the vallecula.

• Recurrent laryngeal nerve - below the vocal cords

The sensory supply to the larynx is from the:

• Superior laryngeal nerve - above the vocal cords
• Recurrent laryngeal nerve - below the vocal cords

This provides the sensory supply to the larynx below the vocal cords and the motor supply to all the intrinsic muscles of the larynx, apart from the cricothyroid muscle (Fig 1b).

The right recurrent laryngeal nerve passes under the subclavian artery to ascend to the larynx in the groove between the oesophagus and the trachea.

The left recurrent laryngeal nerve passes under the aortic arch to ascend in the groove between the oesophagus and the trachea.