Question

Tongue is innervated by these cranial nerves
(A). IVth
(B). Vth
(C). VIIth
(D). IXth
Choose the correct answer from the options given below:

• A. (A), (B) and (D) only.
• B. (A), (B) and (C) only.
• C. (A), (B), (C) and (D).
• D. (B), (C) and (D) only.

Hint:

The tongue's sensory innervation is split into two regions:
- Anterior 2/3: CN V (general feel) + CN VII (taste).
- Posterior 1/3: CN IX (both feel and taste).

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
The tongue has a complex developmental origin, arising from several pharyngeal arches.
As a result, it receives sensory, special sensory (taste), and motor innervation from multiple different cranial nerves.

Step 2: Detailed Explanation:
Let us analyze the cranial nerves that supply the tongue:
- Cranial Nerve V (Trigeminal) (B): The lingual nerve, a branch of the mandibular division of CN V, provides general somatic sensation (temperature, pain, touch) to the anterior two-thirds of the tongue. Thus, CN V is involved.
- Cranial Nerve VII (Facial) (C): The chorda tympani nerve, a branch of CN VII, joins the lingual nerve to provide special sensory taste sensation to the anterior two-thirds of the tongue. Thus, CN VII is involved.
- Cranial Nerve IX (Glossopharyngeal) (D): This nerve provides both general somatic sensation and special taste sensation to the posterior one-third of the tongue. Thus, CN IX is involved.
- Evaluating Cranial Nerve IV (Trochlear) (A): The trochlear nerve is a motor nerve that exclusively innervates the dorsal oblique extraocular muscle of the eye. It plays no role in tongue innervation.
Therefore, only cranial nerves V, VII, and IX are involved in the innervation of the tongue.

Step 3: Final Answer:
The cranial nerves that innervate the tongue are (B), (C), and (D). This corresponds to option (D).