Number of cranial nerves in mammals in a. 10 pairs b. 8 pairs c. 12 pairs d. 16 pairs
Hint: The cranial nerves are sequentially numbered from the front of the brain to the back, in relation to their location. They arise from the brain's surface, and move through the skull's base foramina.
Complete answer: > Option A is incorrect. Cranial nerves are the nerves that originate from the brainstem and pass through the openings of the skull to the periphery of the head. Fish and amphibians have 10 pairs of nerves since the successor nerves are not surrounded by the skull and are also known as spinal nerves. The fish's first spinal nerve is large and supports gill and opercular structures designed to be integrated into the skull.
> Option B is incorrect. Eight pairs of cranial nerves are present in no species on this planet. Hence, the correct answer in mammals would be 12 pairs of cranial nerves.
> Option C is correct. Cranial nerves are the peripheral nervous system's paired nerves which directly connect the muscles and sense organs of the head and thoracic region to the brain. There are 12 pairs of cranial nerves in mammals including olfactory, visual, oculomotor, trochlear, trigeminal, abducens, facial, vestibulocochlear, glossopharyngeal, vagus, peripheral, and hypoglossal. These nerves transmit information between the brain and body parts, mainly to and from head and neck areas, such as the specific senses of vision, taste, smell and hearing.
> Option D is incorrect. No organisms can be found in this world, with 16 pairs of cranial nerves. So, 12 pairs of cranial nerves in mammals would be the correct answer.
Hence, The correct answer is option (C).
Note: The cranial nerves mainly include motor and sensory supply to the structures within the head and neck. The sensory supply includes both "normal" sensation like temperature and touch, and "individual" senses like taste, vision, smell, balance, and hearing. The vagus nerve (X) provides a sensory and autonomic (parasympathetic) supply to neck structures and even to most chest and abdominal organs.