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

9. Muscle Tissue

Introduction to Muscles and Muscle Tissue

Anatomy & Physiology

9. Muscle Tissue

Introduction to Muscles and Muscle Tissue

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Multiple Choice

Which muscle acts as the prime mover of the extension of the arm at the shoulder joint?

Triceps brachii

Biceps brachii

Pectoralis major

Deltoid

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Verified step by step guidance

Step 1: Understand the movement described in the problem. The extension of the arm at the shoulder joint refers to moving the arm backward, away from the front of the body, which involves the posterior muscles of the shoulder and arm.

Step 2: Review the anatomy of the muscles listed in the options. The triceps brachii is primarily responsible for extending the forearm at the elbow joint, not the shoulder. The biceps brachii is involved in flexion of the forearm and supination, not extension. The pectoralis major is responsible for flexion, adduction, and medial rotation of the arm, not extension.

Step 3: Focus on the deltoid muscle. The deltoid has three parts: anterior, middle, and posterior. The posterior fibers of the deltoid are responsible for extension of the arm at the shoulder joint.

Step 4: Confirm the role of the posterior deltoid as the prime mover for arm extension at the shoulder joint. It works by contracting and pulling the humerus backward, enabling the extension movement.

Step 5: Conclude that the correct answer is 'Deltoid,' specifically the posterior fibers, as they act as the prime mover for the extension of the arm at the shoulder joint.