Question

All cranial nerves are related to parasympathetic nerve fibers except
A. Oculomotor
B. Facial
C. Accessory spinal
D. Vagus

Answer 1

Hint: Cranial nerves emerge from the brain including the brainstem, that relay information between the brain and different parts of the body including vision, taste, smell, and hearing. There are twelve pairs of the cranial nerve which includes the Olfactory nerve (I), Optic nerve(II), Oculomotor nerve(III), Trochlear nerve (IV), Trigeminal nerve (V), Abducens nerve (VI), Facial nerves (VII), Auditory nerve (VIII), Glossopharyngeal nerve (IX), Vagus nerve (X), Spinal accessory nerve (XI), Hypoglossal nerve (XII).

Complete answer:
The cranial nerve is part of the Peripheral Nervous System (PNS) but structurally Olfactory (I), Optic (II), Trigeminal (V) nerves are part of the Central Nervous System (CNS).

The parasympathetic Nervous System is one of the divisions of the Peripheral Nervous System that is responsible for activities that occur during rest. Nerve fibers of the parasympathetic nervous system arise from the central nervous system. Cranial nerves specifically, the Oculomotor nerve (III), Facial nerve (VII), Glossopharyngeal (IX), and Vagus nerve (X) receive parasympathetic fibers. Three spinal nerves which lie in the sacrum (S2, S3, S4) called pelvic splanchnic nerves also receive parasympathetic fibers.

The parasympathetic Nervous System promotes the synthesis of glycogen, digestion, and other normal day-to-day functions. It increases the activity of intestinal muscles, increases gastric secretion, and causes relaxation of the pyloric sphincter, and helps in digestion and absorption of food.

As only cranial nerve (III), (VII), (IX), (X) is involved in parasympathetic relay, the Accessory Spinal nerve which is (XI) nerve is not associated with parasympathetic fibers.

So, the correct answer is Option (C) Accessory Spinal.

Note: Apart from the Parasympathetic Nervous System, there is another division of the Peripheral Nervous System, which is called the Sympathetic Nervous system responsible for activities during fight or flight response. These two divisions together constitute the Autonomic Nervous System.