Table of contents

1. Introduction to Anatomy & Physiology5h 43m
2. Cell Chemistry & Cell Components12h 36m
3. Energy & Cell Processes10h 6m
4. Tissues & Histology10h 3m
5. Integumentary System2h 20m
6. Bones & Skeletal Tissue2h 16m
7. The Skeletal System2h 35m
8. Joints2h 17m
9. Muscle Tissue2h 33m
10. Muscles1h 11m
11. Nervous Tissue and Nervous System1h 35m
12. The Central Nervous System1h 6m
- Introduction to the Central Nervous System
  18m
- The Cerebrum
  48m
13. The Peripheral Nervous System1h 26m
14. The Autonomic Nervous System1h 38m
15. The Special Senses2h 41m
16. The Endocrine System2h 48m
17. The Blood3h 22m
18. The Heart3h 42m
19. The Blood Vessels3h 35m
20. The Lymphatic System3h 16m
21. The Immune System14h 37m
22. The Respiratory System3h 20m
23. The Digestive System2h 5m
24. Metabolism and Nutrition4h 0m
25. The Urinary System2h 39m
26. Fluid and Electrolyte Balance, Acid Base Balance37m
27. The Reproductive System2h 5m
28. Human Development1h 21m
29. Heredity3h 32m

10. Muscles

Muscle Actions

Anatomy & Physiology

10. Muscles

Muscle Actions

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Problem 9.1a

Textbook Question

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?

Verified step by step guidance

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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