Which of the following cranial nerves is NOT involved with eyes?

Appeared in: UPRVUNL - 2021

Explanation

The Accessory nerve, or Cranial Nerve XI, is a motor nerve.
Its primary function is to innervate the sternocleidomastoid and trapezius muscles.
These muscles are responsible for turning the head, flexing the neck, and shrugging the shoulders.
The Accessory nerve has no sensory or motor function related to the eyes.

Option A: The Optic nerve (CN II) is entirely dedicated to the sense of vision, transmitting signals from the retina to the brain.
Option C: The Abducens nerve (CN VI) is a motor nerve that innervates the lateral rectus muscle, which abducts the eye (moves it laterally).
Option D: The Trochlear nerve (CN IV) is a motor nerve that innervates the superior oblique muscle, responsible for moving the eye downward and inward.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Functions of Cranial Nerves as background academic context rather than a clinical decision trigger.
A thorough cranial nerve examination is a fundamental part of a neurological assessment, helping nurses and doctors to localize potential lesions in the brainstem or along the nerve pathways.
Damage to the Accessory nerve (e.g., from neck surgery or trauma) can lead to a drooping shoulder, winging of the scapula, and weakness in turning the head against resistance.
What if a patient presents with double vision and an inability to look outward with one eye? This would suggest a palsy of the Abducens nerve (CN VI), a critical finding that requires investigation for causes like increased intracranial pressure, microvascular disease (common in diabetes), or a tumor.

How to Approach the Question

First, identify the core of the question. It asks to find the cranial nerve that is an exception—the one NOT involved with the eyes.
Systematically review the function of each option provided.
Recall or deduce the function of the Optic nerve (CN II). The name itself implies vision. This nerve is involved with the eyes.
Recall the function of the Abducens nerve (CN VI). 'Abducens' relates to 'abduction,' or moving away from the midline. This nerve moves the eye outward.
Recall the function of the Trochlear nerve (CN IV). This nerve controls the superior oblique muscle of the eye.
Recall the function of the Accessory nerve (CN XI). This nerve controls muscles in the neck and shoulder (trapezius and sternocleidomastoid). It has no role in eye function.

Concept Tested & Keywords

Concept Tested: Functions of Cranial Nerves
Stem keywords: cranial nerves, eyes
Lead-in keywords: NOT
Negative lead-in flag: The question asks to identify the option that does NOT fit the criteria.

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E6 Medicine Harrison 22e Part 2 p. 1462-1464

E6 Medicine Harrison 22e Part 1 p. 276-278

E6 Anatomy Grays 43e Vol 1 Part 3 p. 99-101

Practise the full UPRVUNL - 2021

Attempt every question from this paper in a timed mock, then review the full solution for each one.