The cranial nerve affected in Bell's Palsy is:

ESIC Nursing Officer -2019 (Shift -1)

Applied Physiology

Easy

Appeared in: ESIC Nursing Officer -2019 (Shift -1)

Explanation

Bell's Palsy is defined as an idiopathic, unilateral paralysis of the facial muscles.
This paralysis is caused by inflammation and swelling of the seventh cranial nerve (CN VII), also known as the facial nerve.
The facial nerve controls the muscles of facial expression, so its dysfunction leads to the characteristic signs of Bell's Palsy, such as facial drooping.
The condition is distinct from disorders of other cranial nerves, which have different functions related to sensation, eye movement, or swallowing.

Option B: Cranial nerve IX, the glossopharyngeal nerve, is primarily responsible for taste on the posterior third of the tongue, sensation from the pharynx, and swallowing. It does not control the muscles of facial expression.
Option C: Cranial nerve V, the trigeminal nerve, is the main sensory nerve for the face and also controls the muscles of mastication (chewing). While it provides sensation to the face, it does not control the muscles of expression that are paralyzed in Bell's Palsy.
Option D: Cranial nerve III, the oculomotor nerve, controls most of the eye's movements, the constriction of the pupil, and helps lift the eyelid. Its dysfunction affects eye movement, not the muscles of the lower face.

Visual 1: Diagram - An illustration of the 12 cranial nerves, highlighting the path of the facial nerve (CN VII) to show its distribution across the face.
Visual 2: Infographic - A side-by-side comparison of a normal face and a face affected by Bell's Palsy, labeling key signs like eyebrow droop, inability to close the eye, and drooping of the mouth corner.
Visual 3: Flowchart - A simple flowchart showing the proposed pathophysiology: Viral Infection -> Inflammation of CN VII -> Nerve Compression -> Facial Paralysis.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Anatomy and pathophysiology of Bell's Palsy and the function of cranial nerves as background academic context rather than a clinical decision trigger.
The most critical nursing intervention for a patient with Bell's Palsy is protecting the eye on the affected side. Since the patient cannot blink or close their eyelid completely, the cornea is at high risk for drying, abrasion, or ulceration. Instilling artificial tears and applying an eye patch are essential.
Patient education is key. Reassure the patient that the condition is not a stroke and that most people have a full recovery. Teach facial exercises to maintain muscle tone and prevent atrophy.
What if? If a patient with facial weakness also presents with weakness in the arm and leg on the same side, it is a medical emergency. This pattern suggests a central cause like a stroke (supranuclear lesion), not Bell's Palsy (a peripheral nerve lesion), and requires immediate escalation and neuroimaging.

How to Approach the Question

First, identify the key term in the question: 'Bell's Palsy'.
This is a factual recall question that requires knowledge of basic neuroanatomy.
Recall the definition of Bell's Palsy, which is paralysis of the facial muscles.
Connect the function (facial muscle control) to the correct cranial nerve. The facial nerve (CN VII) is named for its primary function.
Mentally review the functions of the other options to confirm they are incorrect. CN V is for sensation/chewing, CN IX is for swallowing/taste, and CN III is for eye movement. This process of elimination confirms CN VII is the only logical answer.

Concept Tested & Keywords

Concept Tested: Anatomy and pathophysiology of Bell's Palsy and the function of cranial nerves.
Stem keywords: Bell's Palsy, cranial nerve
Lead-in keywords: affected in
Negative lead-in flag: false

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