Sensory nerve supply of larynx below the level of vocal cord is:
**Core Concept**
The larynx receives its sensory innervation from various nerves, which are crucial for the protection of the airway and maintenance of vocal cord function. The sensory nerve supply of the larynx below the level of the vocal cord is primarily provided by the recurrent laryngeal nerve, a branch of the vagus nerve.
**Why the Correct Answer is Right**
The recurrent laryngeal nerve provides sensory innervation to the larynx below the level of the vocal cord, including the mucous membrane lining the laryngeal cartilages, the epiglottis, and the aryepiglottic fold. This nerve also supplies the mucous membrane of the laryngeal ventricle and the saccule. The recurrent laryngeal nerve plays a vital role in the sensation of the larynx, enabling the individual to detect irritants and maintain a patent airway.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the internal laryngeal nerve, a branch of the superior laryngeal nerve, provides sensory innervation to the larynx above the level of the vocal cord, not below.
* **Option B:** This option is incorrect because the external laryngeal nerve, another branch of the superior laryngeal nerve, primarily supplies the cricothyroid muscle, not the sensory innervation of the larynx below the vocal cord.
* **Option D:** This option is incorrect because the superior laryngeal nerve, which includes both internal and external branches, provides sensory innervation to the larynx above the level of the vocal cord, not below.
**Clinical Pearl / High-Yield Fact**
The recurrent laryngeal nerve is often injured during thyroid surgery, leading to vocal cord paralysis and alterations in the sensory innervation of the larynx.
**Correct Answer:** C.