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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Multiple Choice

The biceps brachii and brachialis both perform which of the following actions?

Abduction of the shoulder

Flexion of the elbow

Extension of the elbow

Pronation of the forearm

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Verified step by step guidance

Step 1: Begin by identifying the anatomical location and function of the biceps brachii and brachialis muscles. The biceps brachii is located in the anterior compartment of the upper arm and is primarily responsible for flexion of the elbow and supination of the forearm. The brachialis is also located in the anterior compartment and is a major flexor of the elbow.

Step 2: Understand the action of flexion at the elbow joint. Flexion refers to the movement that decreases the angle between the forearm and the upper arm, bringing the forearm closer to the body.

Step 3: Evaluate the other options provided in the question. Abduction of the shoulder involves moving the arm away from the midline of the body, which is performed by muscles like the deltoid, not the biceps brachii or brachialis. Extension of the elbow involves increasing the angle at the elbow joint, which is performed by the triceps brachii. Pronation of the forearm involves rotating the forearm so the palm faces downward, which is performed by muscles like the pronator teres and pronator quadratus.

Step 4: Compare the correct answer, 'Flexion of the elbow,' with the known actions of the biceps brachii and brachialis. Both muscles are involved in flexing the elbow joint, making this the correct choice.

Step 5: Conclude that the biceps brachii and brachialis are synergistic muscles that work together to perform flexion of the elbow, and this action aligns with their anatomical function and location.