Question

The cranial nerve which arises from the lateral side of the medulla oblongata and supplies the snout and jaws

• A. Trochlear
• B. Abducens
• C. Trigeminal
• D. Vagus

Hint:

Think of the Trigeminal nerve (V) as the "dentist's nerve." Just as it supplies your teeth and jaws, it does the same for a fish. It is the primary somatosensory nerve of the head.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
The question asks for the identity of a specific cranial nerve based on its origin (medulla oblongata) and its innervation area (snout and jaws).
Detailed Explanation:

• Cranial Nerve V (Trigeminal): This is the largest cranial nerve. In fishes, it arises from the lateral side of the anterior medulla oblongata/pons region. It is a mixed nerve (sensory and motor).

• Innervation: It divides into several branches. The maxillary and mandibular branches are responsible for supplying the jaws and the ophthalmic branch supplies the snout/forehead region. This matches the description in the question perfectly.

• Analysis of other options:
• Trochlear (IV): Arises from the midbrain and supplies the superior oblique eye muscle.

• Abducens (VI): Arises from the ventral surface of the medulla and supplies the lateral rectus eye muscle.

• Vagus (X): Arises from the medulla but primarily supplies the gills, heart, and digestive tract (viscera).

Step 2: Final Answer:
The Trigeminal nerve (Cranial Nerve V) is the one that supplies the snout and jaws.