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 11

Textbook Question

The muscles that rotate the radius without producing either flexion or extension of the elbow are the
(a) Brachialis and brachioradialis
(b) Pronator teres and supinator
(c) Biceps brachii and triceps brachii
(d) a, b, and c.

Verified step by step guidance

Understand the question: The problem is asking which muscles are responsible for rotating the radius without causing flexion or extension at the elbow joint. This means we are looking for muscles that specifically perform rotational movements (pronation or supination) of the forearm.

Review the anatomy of the forearm: The radius is one of the two bones in the forearm, and its rotation is responsible for pronation (palm facing downward) and supination (palm facing upward). The muscles involved in these movements are located in the forearm and attach to the radius.

Analyze the options: (a) The brachialis and brachioradialis are primarily involved in flexion of the elbow, not rotation. (b) The pronator teres and supinator are specifically responsible for pronation and supination of the forearm, respectively, without causing flexion or extension at the elbow. (c) The biceps brachii and triceps brachii are primarily involved in flexion and extension of the elbow, not rotation.

Focus on the correct muscles: The pronator teres rotates the radius medially (pronation), and the supinator rotates the radius laterally (supination). These muscles act directly on the radius to produce rotation without affecting the elbow joint's flexion or extension.

Conclude the correct answer: Based on the analysis, the correct choice is the pair of muscles that perform rotation of the radius without causing flexion or extension at the elbow. This corresponds to option (b), the pronator teres and supinator.

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Key Concepts

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

Forearm Rotation

Forearm rotation refers to the movement of the radius and ulna bones in the forearm. This movement can occur in two primary directions: pronation, where the palm faces down, and supination, where the palm faces up. Understanding these movements is essential for identifying which muscles are involved in rotating the radius without affecting the elbow joint.

Muscle Functions

Different muscles in the forearm have specific functions related to movement. The pronator teres and supinator are primarily responsible for pronation and supination, respectively. Recognizing the roles of these muscles helps in determining which ones can rotate the radius without causing flexion or extension at the elbow.

Elbow Joint Mechanics

The elbow joint primarily allows for flexion and extension, which are movements that decrease or increase the angle between the forearm and upper arm. Understanding the mechanics of the elbow joint is crucial for analyzing how certain muscles can rotate the radius while keeping the elbow stable and not engaged in flexion or extension.