Sensory supply of Larynk below vocal cord
Wait, the question is specifically about the sensory supply below the vocal cords. The recurrent laryngeal nerve provides sensory innervation to the laryngeal mucosa below the vocal cords in adults. This is important because any injury to the recurrent laryngeal nerve can lead to loss of sensation in that area, which might affect functions like coughing or phonation.
Now, thinking about the options. Let's say the options might include the vagus nerve, the superior laryngeal nerve, the recurrent laryngeal nerve, and maybe some other nerves like the phrenic or glossopharyngeal. The correct answer here should be the recurrent laryngeal nerve.
The superior laryngeal nerve, which is a branch of the vagus, splits into external and internal branches. The internal branch provides sensory innervation above the vocal cords. So if the question is about below, the superior laryngeal nerve isn't the answer. The vagus itself is the main nerve, but the specific branches are what matter here. The recurrent laryngeal nerve is a branch of the vagus, so it's the one responsible for the lower part.
Other nerves like the phrenic or glossopharyngeal aren't involved in laryngeal sensory supply. The phrenic nerve is for the diaphragm, and the glossopharyngeal is for the pharynx, not the larynx. So those can be ruled out.
Clinical pearl: Remember that the sensory innervation of the larynx is split at the level of the vocal cords. Above is superior laryngeal nerve, below is recurrent laryngeal nerve. This is crucial for understanding conditions like laryngeal trauma or nerve injuries. Also, the recurrent laryngeal nerve is vulnerable during thyroid surgery, which can lead to vocal cord paralysis.
**Core Concept** The larynx is divided into two sensory regions by the vocal cords. The area **below the vocal cords** is innervated by the **recurrent laryngeal nerve**, a branch of the vagus nerve (CN X), while the area above is supplied by the internal branch of the superior laryngeal nerve.
**Why the Correct Answer is Right** The **recurrent laryngeal nerve** (a branch of the vagus nerve) provides **sensory supply to the laryngeal mucosa below the vocal cords** in adults. It also innervates all intrinsic laryngeal muscles except the cricothyroid. This nerve loops around the subclavian artery (right) or aortic arch (left) before ascending to the larynx, making it vulnerable to injury during neck/thoracic surgeries.
**Why Each Wrong Option is Incorrect**
**Option A:** *Vagus nerve (CN X)* is incorrect because the vagus itself does not directly supply the larynx—its branches do.
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