Bell's palsy occurs due to lesion of

Appeared in: UPPSC 2017

Explanation

Bell's palsy is defined as an acute, idiopathic, unilateral paralysis of the facial muscles.
This paralysis results from inflammation and dysfunction of the 7th cranial nerve (the facial nerve).
The facial nerve controls all the muscles of facial expression, so its inflammation leads to characteristic signs like a drooping mouth and inability to close the eye on the affected side.
While the exact cause is unknown, it is often linked to a reactivation of a viral infection, such as herpes simplex virus.

Option A: A lesion of the 5th cranial nerve (Trigeminal nerve) primarily affects facial sensation and the muscles used for chewing (mastication).
Option C: The brachial plexus is a network of spinal nerves (C5-T1) that supplies the arm and hand. It is not a cranial nerve and has no function related to the face.
Option D: A lesion of the 12th cranial nerve (Hypoglossal nerve) affects the muscles of the tongue, leading to problems with speech, swallowing, and tongue movement (e.g., the tongue deviates towards the side of the lesion when protruded).

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Cranial Nerve Disorders as background academic context rather than a clinical decision trigger.
Nursing care for a patient with Bell's palsy is crucial for preventing complications. The inability to close the eye can lead to corneal dryness, ulceration, and vision loss. Nurses must educate the patient on eye care, including using artificial tears, wearing an eye patch, and taping the eyelid shut at night.
Psychosocial support is vital. The sudden change in facial appearance can be distressing, and nurses should provide reassurance that the condition is usually temporary and offer support for body image concerns.
Pain management may be necessary, as some patients experience pain behind the ear before or during the paralysis.

How to Approach the Question

First, identify the key term in the question stem: 'Bell's palsy'.
This is a factual recall question that tests your knowledge of common neurological disorders.
Access your memory of the cranial nerves and their associated pathologies.
Recall that Bell's palsy is the specific name for idiopathic paralysis of the facial nerve.
Match 'facial nerve' to its corresponding cranial nerve number, which is VII or the 7th cranial nerve.
Evaluate the other options to confirm your choice. The 5th nerve relates to sensation/chewing, the 12th to the tongue, and the brachial plexus to the arm, none of which match the facial paralysis of Bell's palsy.

Concept Tested & Keywords

QAowFbJltdRIF9f94MOJzx

E6 Medicine Harrison 22e Part 2 p. 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.