Bell’s palsy occurs due to lesion of

Appeared in: UPPSC 2017

Explanation

Bell's palsy is defined as an acute, unilateral paralysis or weakness of the facial muscles.
This condition is caused by inflammation, swelling, or compression of the 7th cranial nerve, also known as the facial nerve.
The facial nerve controls the muscles of facial expression, making its dysfunction the direct cause of the symptoms seen in Bell's palsy, such as facial drooping and inability to close the eye.
The onset is typically abrupt, with maximum weakness developing within 48 hours.

Option A: A lesion of the 5th cranial nerve (trigeminal nerve) affects facial sensation and the muscles of mastication (chewing).
Option C: The brachial plexus is a network of nerves that supplies the arm and hand. It is not a cranial nerve and is not involved in facial movement.
Option D: A lesion of the 12th cranial nerve (hypoglossal nerve) affects the motor function of the tongue.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Etiology of Bell's Palsy and Cranial Nerve Function as background academic context rather than a clinical decision trigger.
Nurses play a key role in managing Bell's palsy by providing supportive care, including eye protection to prevent corneal damage, assisting with nutrition, and offering psychosocial support due to the altered facial appearance.
Patient education is critical, focusing on the nature of the condition, the expected recovery timeline (usually gradual improvement over weeks to months), and the importance of adhering to prescribed treatments like corticosteroids.
What if? If a patient presented with facial drooping AND weakness in their arm and leg on the same side, the priority would shift from Bell's palsy to suspecting a stroke (cerebrovascular accident), requiring immediate emergency medical services activation.

How to Approach the Question

First, identify the key term in the question: "Bell's palsy".
Recall the definition and pathophysiology of Bell's palsy from your knowledge of neurological disorders. The core feature is unilateral facial paralysis.
Connect this primary symptom to the function of the cranial nerves. The facial nerve (cranial nerve VII) is responsible for controlling the muscles of facial expression.
Evaluate the options based on this connection. The 5th nerve relates to sensation/chewing, the brachial plexus to the arm, and the 12th nerve to the tongue.
Eliminate the options related to other functions and select the option that correctly identifies the nerve responsible for facial expression.

Concept Tested & Keywords

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E6 Medicine Harrison 22e Part 2 pp. 1459-1461, 1458-1460

E6 Nelson Textbook of Pediatrics(2024) — Volume 2 p. 1714-1716

Practise the full UPPSC 2017

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