Which nerve maintains hearing and balance?

Appeared in: AIIMS Raipur NO - 2019 (Shift-2)

Explanation

The Vestibulocochlear nerve (CN VIII) is a special sensory nerve with two primary functions: hearing and equilibrium (balance).
It is composed of two distinct parts: the cochlear nerve, which transmits auditory signals, and the vestibular nerve, which transmits signals related to balance and head position.
Damage to this nerve can lead to symptoms like hearing loss, tinnitus (ringing in the ears), and vertigo (dizziness or a spinning sensation).

Option B: The Vagus nerve (CN X) is primarily involved in parasympathetic control of the viscera (heart, lungs, digestive tract), as well as motor control of the larynx and pharynx for speech and swallowing.
Option C: The Facial nerve (CN VII) is mainly responsible for controlling the muscles of facial expression, taste from the anterior part of the tongue, and stimulating salivary and lacrimal glands.
Option D: The Trochlear nerve (CN IV) is a motor nerve that innervates a single extraocular muscle, the superior oblique, which helps move 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 nurse must be able to perform a basic cranial nerve assessment. For CN VIII, this includes the whisper test for hearing and observing the patient's gait and balance (Romberg test).
Complaints of dizziness (vertigo), ringing in the ears (tinnitus), or sudden hearing loss are red flags that require a thorough neurological assessment and prompt reporting to the physician.
What if? If a patient presents with unilateral hearing loss, vertigo, AND facial drooping on the same side, the nurse should suspect a potential lesion, such as an acoustic neuroma (a tumor on CN VIII), which can compress the nearby facial nerve (CN VII) as it grows. This requires urgent neurosurgical evaluation.

How to Approach the Question

First, identify the key functions mentioned in the question: 'hearing' and 'balance'.
This is a factual recall question that requires knowledge of the 12 cranial nerves and their specific functions.
Systematically review the options and match the functions to the correct nerve.
Recall that 'cochlea' relates to hearing and 'vestibular system' relates to balance.
The name 'Vestibulo-cochlear' itself provides a strong clue, as it combines the terms for the two systems it serves.
Eliminate the other nerves based on their known primary functions: Vagus (visceral control), Facial (facial muscles), and Trochlear (eye movement).

Concept Tested & Keywords

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E6 Anatomy Grays 43e Vol 1 Part 3 p. 34-36

E6 Anatomy Applied Ashalatha 4e p. 430-432

Practise the full AIIMS Raipur NO - 2019 (Shift-2)

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