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.
It has two main divisions: the cochlear nerve, which is responsible for transmitting sound information, and the vestibular nerve, which is responsible for transmitting information about balance and head position.
Therefore, it is the single cranial nerve that maintains both hearing and balance.

Option B: The Vagus nerve (CN X) is primarily involved in autonomic functions of the thoracic and abdominal viscera, as well as motor control of the larynx and pharynx. It does not have a primary role in hearing or balance.
Option C: The Facial nerve (CN VII) controls the muscles of facial expression, taste from the anterior part of the tongue, and secretion from lacrimal and salivary glands. It is not involved in hearing or balance, although it does innervate the stapedius muscle in the middle ear.
Option D: The Trochlear nerve (CN IV) is a motor nerve that innervates a single muscle of the eye (the superior oblique), which is responsible for moving the eye downward and inward. It has no function related to hearing or balance.

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.
Nurses assess CN VIII function at the bedside using simple tests. Hearing can be checked with a whisper test, and balance can be assessed with the Romberg test, where the patient stands with feet together and eyes closed.
Damage to CN VIII, for example from an acoustic neuroma (a tumor on the nerve), can cause a combination of hearing loss, tinnitus (ringing in the ear), and vertigo (dizziness/loss of balance). Recognizing these symptoms is crucial for early diagnosis and intervention.
What if? If a patient presents with sudden-onset vertigo but their hearing is perfectly normal, the issue might be with the vestibular branch of CN VIII specifically, or a central cause in the brainstem or cerebellum, rather than a problem affecting the entire nerve or the cochlea.

How to Approach the Question

First, identify the key functions mentioned in the question: 'hearing' and 'balance'.
Next, recall the 12 cranial nerves and their primary functions. This is a foundational knowledge recall question.
Systematically review the options provided and match the functions to the correct nerve.
The Vestibulocochlear nerve's name itself is a clue: 'vestibulo-' relates to the vestibular system (balance) and '-cochlear' relates to the cochlea (hearing).
Eliminate the other nerves based on their known primary roles: Vagus (visceral control), Facial (facial muscles), and Trochlear (eye movement).

Concept Tested & Keywords

QlRWqc_mu1VPh1oOvRgwxf

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

E6 Anatomy Applied Ashalatha 4e p. 430-432

E6 Nelson Textbook of Pediatrics(2024) — Volume 2 p. 1360-1362

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.