Mark the incorrect pair:

Options

A. Ulnar nerve -Musician nerve
B. Median nerve -Labourer's nerve
C. Jacobson's - Branch of IX nerve cranial nerve
D. Trochlear nerve - Dentist nerve

Answer

To solve the question of identifying the incorrect pair, we will analyze each option provided in the question step by step.

### Step-by-Step Solution:

1. **Identify the First Pair: Ulnar Nerve - Musician's Nerve**
- The ulnar nerve is indeed referred to as the musician's nerve because it controls the fine movements of the fingers, which are essential for playing musical instruments.
- **Conclusion**: This pair is **correct**.

2. **Identify the Second Pair: Median Nerve - Laborer Nerve**
- The median nerve is the main nerve of the forearm and is often referred to as the laborer nerve due to its role in hand movements and grip.
- **Conclusion**: This pair is **correct**.

3. **Identify the Third Pair: Jacobson's Branch of the 9th Nerve - Cranial Nerve**
- Jacobson's branch is indeed a branch of the glossopharyngeal nerve (9th cranial nerve) and is correctly matched.
- **Conclusion**: This pair is **correct**.

4. **Identify the Fourth Pair: Trochlear Nerve - Dentist Nerve**
- The trochlear nerve is not known as the dentist nerve. The dentist nerve is more commonly referred to as the inferior alveolar nerve, which is associated with dental procedures.
- **Conclusion**: This pair is **incorrect**.

### Final Answer:
The incorrect pair is **Trochlear Nerve - Dentist Nerve** (Option 4).

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