Paralysis of jaw muscles is due to loss of function of which cranial nerve ?

Options

A. III
B. V
C. VII
D. X

Answer

**Step-by-Step Solution:**

1. **Understanding Cranial Nerves**: The human body has 12 pairs of cranial nerves, each with specific functions. It is essential to identify which cranial nerve is responsible for the movement of the jaw muscles.

2. **Identifying Relevant Cranial Nerves**: The question asks about paralysis of jaw muscles. The cranial nerves that could potentially be involved include:
- Oculomotor nerve (Cranial Nerve III)
- Trigeminal nerve (Cranial Nerve V)
- Facial nerve (Cranial Nerve VII)
- Vagus nerve (Cranial Nerve X)

3. **Analyzing Functions of Each Nerve**:
- **Oculomotor Nerve (Cranial Nerve III)**: Primarily responsible for eye movements and pupil constriction. It does not control jaw muscles.
- **Trigeminal Nerve (Cranial Nerve V)**: This nerve has both sensory and motor functions. It is responsible for sensation in the face and motor functions such as chewing (jaw movement).
- **Facial Nerve (Cranial Nerve VII)**: Controls facial expressions and taste sensations but does not directly control jaw muscles.
- **Vagus Nerve (Cranial Nerve X)**: Involved in autonomic functions like digestion and heart rate, not in jaw movement.

4. **Conclusion**: Since the trigeminal nerve (Cranial Nerve V) is responsible for the motor functions of the jaw muscles (specifically through its mandibular branch), paralysis of the jaw muscles is due to the loss of function of the trigeminal nerve.

5. **Final Answer**: The cranial nerve responsible for the paralysis of jaw muscles is the **Trigeminal Nerve (Cranial Nerve V)**.

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