Question

Which of the following cranial nerves is responsible for the motor innervation of the muscles of mastication?

• A. Trigeminal nerve
• B. Facial nerve
• C. Glossopharyngeal nerve
• D. Hypoglossal nerve

Hint:

Remember: Trigeminal nerve (V) = sensory to face + motor to muscles of mastication.

Answer 1

The Correct Option is A

In the context of cranial nerves and their functions, the task is to identify which nerve is responsible for the motor innervation of the muscles of mastication (chewing). Understanding the role of each cranial nerve is crucial:-

1. Trigeminal Nerve (Cranial Nerve V): The trigeminal nerve is mainly responsible for sensation in the face. It has three branches, but the mandibular branch specifically provides motor innervation to the muscles of mastication. These muscles include the masseter, temporalis, medial pterygoid, and lateral pterygoid. Thus, the trigeminal nerve enables the movement involved in chewing.

2. Facial Nerve (Cranial Nerve VII): This nerve controls the muscles of facial expression, not mastication. It is involved in other functions like blinking and smiling.

3. Glossopharyngeal Nerve (Cranial Nerve IX): It mainly innervates the pharynx and is involved in the gag reflex and swallowing, not mastication.

4. Hypoglossal Nerve (Cranial Nerve XII): This nerve controls tongue movements but is not involved in mastication directly.

Given these explanations, the Trigeminal nerve is responsible for the motor innervation of the muscles of mastication.

Answer 2

The cranial nerves are an essential part of the peripheral nervous system, and they have various functions including sensory, motor, or both. In this context, we need to identify which of the listed cranial nerves provides motor innervation to the muscles involved in mastication.

Here's how to solve this:

1. Identify the function of each cranial nerve provided in the options:
   • Trigeminal nerve (Cranial Nerve V): This nerve is responsible for sensory innervation to the face as well as motor innervation to the muscles of mastication, including the masseter, temporalis, medial pterygoid, and lateral pterygoid muscles.
   • Facial nerve (Cranial Nerve VII): This nerve primarily handles motor functions for facial expression muscles and also provides taste sensations to the anterior two-thirds of the tongue.
   • Glossopharyngeal nerve (Cranial Nerve IX): This nerve is involved in taste and sensory functions in the posterior one-third of the tongue and also assists in swallowing.
   • Hypoglossal nerve (Cranial Nerve XII): This nerve primarily controls the muscles of the tongue.
2. Determine which nerve has the motor function for chewing (mastication).
3. The correct choice is the Trigeminal nerve as it innervates the muscles responsible for this function.

By understanding these functions, we can confirm that the correct answer is the Trigeminal nerve