Impluse generated in the taste buds of the tongue reach the cerebral cortex via:
**Core Concept**
The transmission of taste sensations from the tongue to the brain is a complex process involving multiple neural pathways. The primary taste pathways are mediated by the facial nerve (cranial nerve VII) and the glossopharyngeal nerve (cranial nerve IX), which convey taste information from the anterior two-thirds and posterior one-third of the tongue, respectively.
**Why the Correct Answer is Right**
The impulses generated in the taste buds of the tongue are transmitted to the brain through the facial nerve (cranial nerve VII) and the glossopharyngeal nerve (cranial nerve IX). These nerves contain sensory fibers that synapse in the solitary nucleus of the brainstem, from where the taste information is relayed to the ventral posterior medial nucleus of the thalamus. The thalamus then sends the taste information to the primary gustatory cortex in the insula, which is responsible for processing and interpreting the taste sensations. The insula is located in the frontal and parietal lobes of the cerebral cortex.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the transmission of taste sensations from the tongue to the brain.
**Option B:** The vagus nerve (cranial nerve X) is primarily involved in conveying sensory information from the viscera and is not directly involved in the transmission of taste sensations from the tongue.
**Option C:** The trigeminal nerve (cranial nerve V) is primarily involved in conveying sensory information from the face and is not directly involved in the transmission of taste sensations from the tongue.
**Clinical Pearl / High-Yield Fact**
The loss of taste sensation, known as ageusia, can be caused by damage to the facial nerve (cranial nerve VII) or the glossopharyngeal nerve (cranial nerve IX), which are responsible for conveying taste information from the tongue to the brain.
**Correct Answer:** C. The glossopharyngeal nerve (cranial nerve IX) is primarily involved in conveying taste information from the posterior one-third of the tongue.