Which one of the following is the correct sequence of cranial nerves in chordates ?

Options

A. Facial, abducens, auditory, glossopharyngeal
B. Auditory, facial, abdunces, glossopharyngeal
C. Abducens, facial, auditory, glossopharyngeal
D. Glossopharyngeal, facial, auditory, abducens

Answer

To determine the correct sequence of cranial nerves in chordates, we need to identify the order of the specific cranial nerves mentioned in the options provided. Here’s a step-by-step breakdown of the solution:

### Step 1: Understand the Cranial Nerves
Chordates have 12 pairs of cranial nerves that emerge from the brain. Each cranial nerve is numbered based on its position from the front (anterior) to the back (posterior) of the brain.

### Step 2: Identify the Nerves in the Options
The options provided in the question include:
- Option A: Facial, Abducens, Auditory, and Glossopharyngeal
- Option B: Auditory, Facial, Abducens, and Glossopharyngeal
- Option C: Abducens, Facial, Auditory, and Glossopharyngeal
- Option D: Glossopharyngeal, Facial, Auditory, and Abducens

### Step 3: Recall the Order of Cranial Nerves
The relevant cranial nerves for this question are:
- 6th: Abducens
- 7th: Facial
- 8th: Auditory (also known as Vestibulocochlear)
- 9th: Glossopharyngeal

### Step 4: Arrange the Nerves in the Correct Sequence
Based on the numbering:
1. Abducens (6th)
2. Facial (7th)
3. Auditory (8th)
4. Glossopharyngeal (9th)

Thus, the correct sequence is: Abducens, Facial, Auditory, and Glossopharyngeal.

### Step 5: Identify the Correct Option
From the options provided, Option C matches the correct sequence:
- Option C: Abducens, Facial, Auditory, and Glossopharyngeal.

### Conclusion
The correct answer to the question is **Option C**.

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