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

8. Joints

Joint Movements

Anatomy & Physiology

8. Joints

Joint Movements

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Problem 9

Textbook Question

Bone movement at a joint is described around an invisible line known as a/an:
a. Synarthrosis
b. Axis
c. Sagittal plane
d. Amphiarthrosis

Verified step by step guidance

Step 1: Understand the terminology in the question. The problem is asking about the invisible line around which bone movement occurs at a joint. This line is referred to in anatomical terms.

Step 2: Review the options provided: a. Synarthrosis, b. Axis, c. Sagittal plane, d. Amphiarthrosis. Synarthrosis and Amphiarthrosis are types of joints, while Axis and Sagittal plane refer to anatomical concepts.

Step 3: Clarify the concept of 'Axis.' In anatomy, an axis is an invisible line around which rotation or movement occurs. For example, the movement of the head around the atlantoaxial joint occurs around an axis.

Step 4: Compare the term 'Axis' with the other options. Synarthrosis refers to immovable joints, Amphiarthrosis refers to slightly movable joints, and the Sagittal plane is a directional term describing a plane dividing the body into left and right halves. None of these describe the invisible line for movement.

Step 5: Conclude that the correct term describing the invisible line around which bone movement occurs at a joint is 'Axis,' based on the anatomical definition.

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Key Concepts

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

Axis

In biomechanics, the axis refers to an imaginary line around which movement occurs at a joint. It is crucial for understanding how bones rotate and move in relation to one another. Different types of joints have specific axes of rotation, which can be vertical, horizontal, or oblique, influencing the range and type of motion.

Types of Joints

Joints can be classified into several types based on their structure and function, including synarthrosis (immovable), amphiarthrosis (slightly movable), and diarthrosis (freely movable). Understanding these classifications helps in identifying how movement occurs at different joints and the mechanics involved in joint movement.

Planes of Movement

The sagittal plane is one of the three primary anatomical planes and divides the body into left and right halves. Movements that occur in this plane include flexion and extension, which are essential for understanding how joints function during various physical activities. Recognizing the relationship between planes and joint movement is vital for analyzing biomechanics.