Which nerve is involved in Bell's palsy?

Appeared in: Haryana CHO - 2022

Explanation

Bell's palsy is an idiopathic condition causing sudden, unilateral weakness of the facial muscles.
It is caused by inflammation, swelling, or compression of the Facial Nerve, which is Cranial Nerve VII.
The Facial Nerve (CN VII) controls the muscles of facial expression (e.g., smiling, closing the eye), and its dysfunction leads to the characteristic signs of Bell's palsy.
Symptoms include facial drooping, inability to close the eyelid, drooling, and sometimes loss of taste on the anterior part of the tongue.

Option B: The Vagus Nerve (CN X) is primarily involved in autonomic functions of the viscera (like heart rate and digestion), swallowing, and phonation. It does not control the muscles of facial expression.
Option C: The Abducens Nerve (CN VI) is a motor nerve that innervates a single extraocular muscle, the lateral rectus, which is responsible for abducting the eye (moving it outward). It has no role in facial expression.
Option D: The Trigeminal Nerve (CN V) is the primary sensory nerve for the face and controls the muscles of mastication (chewing). While it provides sensation to the face, it does not control the muscles responsible for facial expression.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Cranial Nerve Disorders (Bell's Palsy) as background academic context rather than a clinical decision trigger.
The priority nursing intervention for a patient with Bell's palsy is to protect the affected eye from corneal abrasion and dryness, as the inability to blink or close the eyelid (lagophthalmos) leaves it exposed.
Nurses must educate the patient on using lubricating eye drops, wearing protective eyewear, and taping the eye shut at night.
Psychosocial support is crucial, as the sudden and dramatic change in facial appearance can cause significant emotional distress and body image issues.

How to Approach the Question

First, identify the key pathology mentioned in the question, which is 'Bell's palsy'.
Recognize that this is a factual recall question asking for the specific cranial nerve associated with this well-known condition.
Systematically review the functions of the cranial nerves provided as options.
Recall or deduce that Bell's palsy affects the muscles of facial expression.
Match the function of controlling facial expression to the correct cranial nerve, which is the Facial Nerve (CN VII).
Eliminate the other options by recalling their primary functions: Trigeminal (facial sensation, chewing), Abducens (eye movement), and Vagus (visceral functions).

Concept Tested & Keywords

QfxpT7NUCbDR0K6lRocbpr

E6 Anatomy Applied Ashalatha 4e p. 428-430

E6 Medicine Harrison 22e Part 2 p. 1457-1459

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

Practise the full Haryana CHO - 2022

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