Taste sensations from anterior 2/3rd of tongue are carried by:
## Core Concept
The question tests the understanding of the neural pathway for taste sensations, specifically focusing on the innervation of the tongue. The anterior two-thirds of the tongue is primarily innervated by the **lingual nerve**, a branch of the **mandibular division of the trigeminal nerve (V3)**, for general sensation, and the **chorda tympani nerve**, a branch of the **facial nerve (CN VII)**, for taste.
## Why the Correct Answer is Right
The correct answer, **chorda tympani nerve (a branch of facial nerve)**, is right because it is responsible for transmitting taste sensations from the anterior two-thirds of the tongue. The chorda tympani nerve joins the lingual nerve and, through it, reaches the anterior two-thirds of the tongue. The facial nerve (CN VII) is crucial for the transmission of taste from this part of the tongue.
## Why Each Wrong Option is Incorrect
- **Option A:** The **glossopharyngeal nerve (CN IX)** carries taste sensations from the posterior one-third of the tongue, not the anterior two-thirds. It is involved in the innervation of the stylopharyngeus muscle and provides sensory innervation, including taste, to the posterior tongue.
- **Option B:** The **trigeminal nerve (CN V)** provides general sensory innervation to the face, including the tongue for non-taste sensations like touch and temperature, but it does not directly carry taste sensations.
- **Option D:** The **vagus nerve (CN X)** carries taste sensations from the epiglottis and the back of the throat but not from the tongue.
## Clinical Pearl / High-Yield Fact
A key point to remember is that the **chorda tympani nerve**, a branch of the **facial nerve**, is responsible for taste sensation in the anterior two-thirds of the tongue. Damage to this nerve can result in altered taste sensation in this area. A classic clinical correlation is the potential for taste disturbances following middle ear infections or surgeries that might affect the nerve.
## Correct Answer: C. chorda tympani nerve.