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 Naming

Anatomy & Physiology

10. Muscles

Muscle Naming

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Problem 24

Textbook Question

The muscles of the vertebral column include many posterior extensors but few anterior flexors. Why?

Verified step by step guidance

Understand the function of the vertebral column: The vertebral column is responsible for supporting the body, maintaining posture, and allowing movement. It must counteract the forces of gravity to keep the body upright.

Recognize the role of posterior extensors: Posterior extensor muscles, such as the erector spinae group, are crucial for extending the spine and maintaining an upright posture. These muscles work against gravity to prevent the body from collapsing forward.

Consider the role of anterior flexors: Anterior flexor muscles, such as the abdominal muscles, are involved in flexing the spine and bending forward. However, these muscles are less critical for maintaining posture because gravity naturally pulls the body forward.

Analyze the biomechanical advantage: The posterior extensors are more numerous and powerful because they must constantly work to counteract gravity and stabilize the spine during standing and movement. The anterior flexors are less prominent because their function is not as essential for maintaining posture.

Conclude with evolutionary and functional reasoning: The distribution of muscles reflects the body's adaptation to upright posture and bipedal locomotion. The posterior extensors are prioritized to support the spine and resist gravitational forces, while anterior flexors play a secondary role in specific movements like bending forward.

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Key Concepts

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

Muscle Function and Anatomy

The muscles of the vertebral column are categorized based on their functions: extensors and flexors. Extensors, primarily located posteriorly, are responsible for extending the spine and maintaining an upright posture, while flexors, found anteriorly, are fewer in number. This anatomical arrangement reflects the need for stability and support in the spine, as well as the mechanics of movement.

Postural Stability

Postural stability is crucial for maintaining balance and alignment of the body. The predominance of posterior extensor muscles helps to counteract the forward pull of gravity, providing support to the vertebral column. This stability is essential for activities such as standing, walking, and lifting, where the spine must remain aligned and stable.

Biomechanics of Movement

Biomechanics studies the mechanical aspects of movement in living organisms. In the context of the vertebral column, the balance between extensor and flexor muscles influences how the spine moves and bears loads. The design of the spine, with more extensors, allows for greater control and strength during extension and rotation, which are vital for various physical activities.

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Textbook Question

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Textbook Question

If 'adductor' is part of the name of a muscle, what does that tell you about the muscle?

a. It is a wide muscle.

b. It is a long muscle.

c. It raises a body part.

d. It pulls a body part toward the midline.