Question

Which of the following cranial nerves is a parasympathetic nerve?
A. Facial
B. Auditory
C. Abducens
D. Accessory spinal

Answer 1

Hint: Parasympathetic nerves arise from the central nervous system. Parasympathetic nerves function when the body is at rest. Functions like tears, salivation in the mouth are performed by the parasympathetic cranial nerve for facial activities.

Step by step answer:The parasympathetic nervous system is regarded as part of the autonomic nervous system. It controls various activities like lacrimation (tears), salivation, sexual arousal, digestion, etc. when the body is at rest. The cranial nerves involved are the glossopharyngeal nerve, oculomotor nerve, vagus nerve, and facial nerve.

The facial cranial nerve controls the reflexes of tear generation and salvation in the mouth. This nerve functions by controlling facial glands and arises from the central nervous system under the parasympathetic branch.
The auditory cranial nerve is the part of the vestibulocochlear nerve. This cranial nerve relays auditory sensory information from the cochlea to the brain. This is not a parasympathetic nerve.
The abducens cranial nerve supplies the muscles causing side-to-side movement of eyeballs. It is not included in parasympathetic nerves. As it not only functions at rest but actively participates in fast and slow eyeball movements in an active state of the body.
The accessory spinal nerve has a somatic motor function in muscles. This means that it provides movement and no sensation. It originates from the upper part of the spinal cord and is not a parasympathetic nerve.
Thus, the correct answer is the Facial nerve, option A.

Note: The parasympathetic nerves with sympathetic nerves make up the Autonomous nervous system. The parasympathetic nervous system is different from the sympathetic nervous system as they function for ‘feed or breed’ and ‘flight or fight’ respectively.