Mr. Bell presents with the inability to move certain muscles on one side of his face. You ask him to make various facial expressions and find that on his right side he is unable to purse his lips, pull in his cheeks, elevate his upper lip, and smirk. What muscles is Mr. Bell unable to contract?

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Identify the muscles responsible for the facial expressions Mr. Bell is unable to perform.

For pursing lips, consider the orbicularis oris muscle.

For pulling in cheeks, consider the buccinator muscle.

For elevating the upper lip, consider the levator labii superioris muscle.

For smirking, consider the zygomaticus major muscle.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Facial Muscles

Facial muscles are a group of muscles that control facial expressions. They are primarily innervated by the facial nerve (cranial nerve VII) and include muscles such as the orbicularis oris, buccinator, and zygomaticus. Understanding these muscles is crucial for diagnosing conditions like Bell's palsy, where muscle control is impaired.

Cranial Nerve VII (Facial Nerve)

The facial nerve, or cranial nerve VII, is responsible for the motor control of the facial muscles. It also carries sensory information from the taste buds of the anterior two-thirds of the tongue. Damage to this nerve can lead to weakness or paralysis of facial muscles, as seen in Mr. Bell's case.

Bell's Palsy

Bell's palsy is a condition characterized by sudden, temporary weakness or paralysis of the muscles on one side of the face. It is often caused by inflammation of the facial nerve and can result in difficulty with facial expressions, as well as other symptoms like drooping of the mouth or eyelid. Recognizing the signs of Bell's palsy is essential for appropriate management and treatment.

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