Cranial Nerves: Function, Anatomy And Location

Cranial Nerves: Function, Anatomy And Location

Question 1. Nerve supply to the tongue.
Answer:

1. Motor nerves:

• Palatoglossus muscle – by the cranial root of the vagus nerve
• All other muscles – hypoglossal nerve.

2. Sensory nerves:

• General sensation – lingual nerve.
• A taste sensation for anterior 2/3rd except vallate papillae chorda tympani.
• General sensation and taste for the posterior 1/3rd including circumvallate papillae – glossopharyngeal Posterior most part of the tongue vagus nerve.

Question 2. Pathways of taste.
Answer:

First-order neurons:

• Taste fibers of the facial nerve (VII), glossopharyngeal (IX) nerve, and vagus (X) nerve run, into the nucleus of tractus solitarious (NTS) in the medulla.
• The cell bodies of the second-order neurons are located in NTS and their axons ascend to join the medial lemniscus and terminate with V nerve fibers in the posteroventral nucleus of the thalamus.
• The third-order neurons arise and end in the inferior part of the ipsilateral postcentral gyrus.