Which of these cranial nerves contains preganglionic parasympathetic fibers?
options:
olfactory , ?I
optic, II
oculomotor, III
trochlear, IV
trigeminal, V
abducens, VI
facial, VII
vestibulocochlear, VIII
glossopharyngeal, IX
vagus, X
accessory, XI
hypoglossal, XII
The correct answer and explanation is :
The cranial nerves that contain preganglionic parasympathetic fibers are:
- Oculomotor nerve (III)
- Facial nerve (VII)
- Glossopharyngeal nerve (IX)
- Vagus nerve (X)
Correct Answer:
Oculomotor (III), Facial (VII), Glossopharyngeal (IX), and Vagus (X) contain preganglionic parasympathetic fibers.
Explanation:
The parasympathetic nervous system is responsible for “rest and digest” functions. The preganglionic parasympathetic fibers originate in the brainstem and travel via specific cranial nerves to synapse in ganglia near their target organs.
- Oculomotor Nerve (III)
- Originates in the Edinger-Westphal nucleus.
- Synapses in the ciliary ganglion.
- Controls pupil constriction (miosis) and accommodation of the lens.
- Facial Nerve (VII)
- Originates in the superior salivatory nucleus.
- Synapses in the pterygopalatine and submandibular ganglia.
- Stimulates lacrimal, submandibular, and sublingual glands for tear and saliva production.
- Glossopharyngeal Nerve (IX)
- Originates in the inferior salivatory nucleus.
- Synapses in the otic ganglion.
- Stimulates the parotid gland to produce saliva.
- Vagus Nerve (X)
- Originates in the dorsal motor nucleus of the vagus.
- Has numerous ganglia near thoracic and abdominal organs.
- Provides parasympathetic control to the heart, lungs, and most of the gastrointestinal tract.
Excluded Nerves:
- Olfactory (I), Optic (II), Trochlear (IV), Trigeminal (V), Abducens (VI), Vestibulocochlear (VIII), Accessory (XI), and Hypoglossal (XII) do not contain parasympathetic fibers.
