Question

How many pairs of cranial nerves originate from the brain of a rat?
A. 12.
B. 8.
C. 9.
D. 11.
E. 10.

Answer 1

Hint: The cranial nerves in rats provide motor and sensory supply mainly to the structures within the head and neck. The sensory supply includes both "general" sensation such as temperature and touch, and "special" senses such as taste, vision, smell, balance and hearing.

Complete answer:
There are 12 pairs of cranial nerves that originate from the rat's brain and brain stem. Among these 12, each has specialised functions for different senses of the body.
Olfactory nerve (CN I)
Optic nerve (CN II)
Oculomotor nerve (CN III)
Trochlear nerve (CN IV)
Trigeminal nerve (CN V)
Abducens nerve (CN VI)
Facial nerve (CN VII)
Auditory (or vestibulocochlear)nerve (CN VIII)
Glossopharyngeal nerve (CN IX)
Vagus nerve (CN X)
Spinal accessory nerve(CN XI)
Hypoglossal nerve (CN XII)

Hence, the correct answer is option (A).

Additional information:
Brain of a rat is divided into 3 basic parts.
Cerebral hemispheres - The large cerebral hemispheres lie under the frontal and parietal bones. They are separated by a deep fissure. The cerebral hemispheres are associated with integration of information.
Olfactory bulb- it is a small bulb shape structure that lies anterior to the cerebral hemispheres and posterior to the nasal bones. Olfactory region of the brain is associated with smell.
Cerebellum - The cerebellum is the area between the interparietal bone and posterior cerebral hemispheres. It is divided into three lobes, two lateral hemispheres and one medial vermis. Here the main function of the cerebellum is to control, coordination and maintain body equilibrium.
 Medulla oblongata - The medulla oblongata is the area situated between the cerebellum and the spinal cord. It control and manages heart rate, blood pressure, respiration and hormonal secretions

Note: In rats the cranial nerves are a group of 12 nerves that occur in pairs and arises directly from the brain. The olfactory and optic are the first two pairs of the cranial nerve that arise from the cerebrum, whereas the remaining ten pairs of cranial nerves emerge from the brain stem.