Which nerve provides sensory innervation to the trachea and larynx below the vocal cords?

The recurrent laryngeal nerve is responsible for providing sensory innervation to the trachea and larynx below the vocal cords. This nerve branches off from the vagus nerve and loops around the aorta (on the left side) or the subclavian artery (on the right side) before ascending towards the larynx. Its primary function is to innervate the muscles of the larynx, except for the cricothyroid muscle, and it also carries sensory fibers from the area below the vocal cords, making it crucial for protective reflexes and sensation in this part of the respiratory tract.

The other options serve different functions. The internal laryngeal nerve mainly innervates the area above the vocal cords, while the external laryngeal nerve primarily supplies motor innervation to the cricothyroid muscle and some sensory innervation to the larynx but does not cover the lower parts. The glossopharyngeal nerve, while involved in taste and some aspects of swallowing and gag reflex in the pharynx, does not innervate the larynx or trachea. Therefore, the recurrent laryngeal nerve is the correct answer for sensory innervation below the vocal cords.