the fifth cranial nerve, also known as the trigeminal nerve (CN V), is responsible for general sensation in the face, including the anterior two-thirds of the tongue. This sensation includes touch, pain, and temperature.
The trigeminal nerve has three main divisions:
- Ophthalmic division (V1)
- Maxillary division (V2)
- Mandibular division (V3)
The general sensation from the anterior two-thirds of the tongue is mediated by the mandibular division (V3) of the trigeminal nerve. This branch carries sensory information from the tongue to the brainstem.
Regarding relay in the brainstem, sensory information from the anterior two-thirds of the tongue travels through the mandibular division of the trigeminal nerve and then synapses in the trigeminal sensory nucleus (or trigeminal nucleus) located in the brainstem.
However, the nucleus tractus solitarius (NTS) is primarily associated with processing visceral sensory information, such as taste sensation from the posterior one-third of the tongue via the glossopharyngeal nerve (CN IX) and the vagus nerve (CN X). So, while the NTS is not directly involved in processing general sensation from the anterior two-thirds of the tongue, it does play a role in processing taste sensation from the posterior one-third of the tongue.