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

To allow for flexion, which muscle unlocks the knee joint?

Popliteus

Rectus femoris

Biceps femoris

Gastrocnemius

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Verified step by step guidance

Understand the anatomy of the knee joint: The knee joint is a hinge joint that allows for flexion and extension. It is stabilized by ligaments and muscles, and unlocking the knee is necessary for initiating flexion.

Learn the role of the popliteus muscle: The popliteus is a small muscle located at the back of the knee. Its primary function is to 'unlock' the knee joint by rotating the femur laterally on the tibia when the leg is fixed, or medially rotating the tibia when the leg is free.

Compare the functions of the listed muscles: Rectus femoris is part of the quadriceps group and primarily extends the knee. Biceps femoris is part of the hamstring group and assists in knee flexion but does not unlock the knee. Gastrocnemius is a calf muscle that contributes to plantar flexion and assists in knee flexion but does not unlock the knee.

Identify the correct muscle for unlocking the knee: The popliteus muscle is specifically responsible for unlocking the knee joint to allow flexion, making it unique among the listed muscles.

Conclude that the popliteus muscle is the correct answer based on its anatomical function of unlocking the knee joint to initiate flexion.