Nerve supply of circumvallate papillae is by-
**Core Concept**
The circumvallate papillae are specialized projections on the tongue that house taste buds, responsible for detecting sweet, sour, salty, and bitter tastes. The nerve supply of these papillae is crucial for transmitting taste sensations to the brain. The primary nerve responsible for this function is a branch of the trigeminal nerve.
**Why the Correct Answer is Right**
The circumvallate papillae receive their nerve supply from the glossopharyngeal nerve (cranial nerve IX), specifically through the lingual branch. This nerve branch is responsible for transmitting taste information from the posterior one-third of the tongue, including the circumvallate papillae. The lingual branch of the glossopharyngeal nerve carries sensory fibers that synapse in the nucleus solitarius of the medulla oblongata, ultimately transmitting taste information to the brain.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as the chorda tympani, a branch of the facial nerve (cranial nerve VII), is responsible for taste innervation of the anterior two-thirds of the tongue, not the circumvallate papillae.
**Option B:** This option is incorrect as the lingual nerve, a branch of the mandibular division of the trigeminal nerve (cranial nerve V), provides general sensory innervation to the tongue but not taste sensation.
**Option C:** This option is incorrect as the vagus nerve (cranial nerve X) is responsible for parasympathetic innervation of the tongue and other visceral functions, but not taste sensation.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that the nerve supply of the circumvallate papillae is crucial for assessing taste function in patients with neurological or otolaryngological disorders. A thorough understanding of the nerve supply can aid in diagnosing conditions such as glossopharyngeal neuralgia or taste disorders.
**Correct Answer:** C.