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 forms the posterior border of the armpit and is responsible for extending and adducting the humerus?

Pectoralis major

Biceps brachii

Deltoid

Latissimus dorsi

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Verified step by step guidance

Step 1: Understand the anatomy of the armpit region. The posterior border of the armpit is formed by muscles located on the back side of the body, specifically those involved in movements of the shoulder and arm.

Step 2: Review the function of the latissimus dorsi muscle. This muscle is responsible for extending, adducting, and medially rotating the humerus. It is a large, flat muscle that spans the lower back and inserts into the humerus.

Step 3: Compare the functions of the other muscles listed in the problem. The pectoralis major is located on the anterior chest and primarily functions in flexion and adduction of the humerus. The biceps brachii is involved in flexion of the elbow and supination of the forearm. The deltoid is responsible for abduction of the arm.

Step 4: Identify the muscle that matches the description provided in the problem. The latissimus dorsi forms the posterior border of the armpit and is responsible for extending and adducting the humerus, making it the correct answer.

Step 5: Confirm your understanding by visualizing or referencing anatomical diagrams of the latissimus dorsi and its role in forming the posterior border of the armpit.