CN III : Trivia Questions On Oculomotor Nerve! Quiz

2.

Postganglionic parasympathetic fibers of CN III innervate which muscles?

Superior, inferior and medial rectus muscles
Ciliary muscles
Inferior oblique muscle
Muscles of facial expression
Sphincter pupillae muscles

Correct Answer(s)

A. Ciliary muscles
A. Sphincter pupillae muscles

Explanation

The postganglionic parasympathetic fibers of CN III innervate the ciliary muscles and the sphincter pupillae muscles. These muscles are responsible for controlling the shape of the lens and the size of the pupil, respectively. The ciliary muscles help with accommodation, which is the process of adjusting the lens to focus on near or distant objects. The sphincter pupillae muscles constrict the pupil, reducing the amount of light entering the eye.

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3.

Damage to CN III results in permanent dilatation of the pupil.

True
False

Correct Answer

A. True

Explanation

Damage to the third cranial nerve (CN III) can lead to permanent dilatation of the pupil. CN III is responsible for controlling the muscles that constrict the pupil, so if it is damaged, the pupil may remain dilated. This condition is known as "fixed and dilated pupil" and is often associated with other symptoms such as ptosis (drooping of the eyelid) and eye movement abnormalities. Therefore, the statement that damage to CN III results in permanent dilatation of the pupil is true.

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4.

Postganglionic parasympathetic fibers of CN III travel via which nerves?

Trigeminal nerves
Facial nerves
Short ciliary nerves
Auriculotemporal nerves

Correct Answer

A. Short ciliary nerves

Explanation

The correct answer is short ciliary nerves. The postganglionic parasympathetic fibers of CN III, also known as the oculomotor nerve, travel via the short ciliary nerves. These nerves innervate the ciliary muscles and the sphincter pupillae muscles of the eye, which control accommodation and pupil constriction respectively. The trigeminal nerves are responsible for general sensation in the face, while the facial nerves control the muscles of facial expression. The auriculotemporal nerves are branches of the trigeminal nerve that supply sensory innervation to the skin of the ear and temple region.

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5.

CN III parasympathetic fibers act to...?

Dilate the pupil
Constrict the pupil
Accommodate the lens for near vision
Accommodate the lens for long vision

Correct Answer(s)

A. Constrict the pupil
A. Accommodate the lens for near vision

Explanation

CN III parasympathetic fibers constrict the pupil and accommodate the lens for near vision. The parasympathetic fibers of CN III, also known as the oculomotor nerve, innervate the sphincter pupillae muscle in the iris, causing it to contract and constrict the pupil. This constriction allows less light to enter the eye, thus protecting the retina from excessive light exposure. Additionally, these fibers also innervate the ciliary muscle, which controls the shape of the lens. When the parasympathetic fibers are activated, they cause the ciliary muscle to contract, allowing the lens to become more rounded, which facilitates near vision.

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CN III : Trivia Questions On Oculomotor Nerve! Quiz

Preganglionic parasympathetic fibers of CN III terminate in which ganglion?

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Postganglionic parasympathetic fibers of CN III innervate which muscles?

Damage to CN III results in permanent dilatation of the pupil.

Postganglionic parasympathetic fibers of CN III travel via which nerves?

CN III parasympathetic fibers act to...?