The example of pivot joint is

Options

A. hip joints
B. metacarpophalangeal joints
C. ankle joints
D. radioulnar joints

Answer

To determine the example of a pivot joint from the given options, we will analyze each option based on the characteristics of pivot joints.

### Step-by-Step Solution:

1. **Understand the Definition of a Pivot Joint:**
A pivot joint is a type of synovial joint where the rounded end of one bone fits into a ring formed by another bone. This structure allows for rotational movement around an axis.

2. **Analyze the Options:**
- **Hip Joints:** These are ball and socket joints, allowing for a wide range of movement but not specifically rotational movement around an axis. Therefore, hip joints are not an example of a pivot joint.
- **Metacarpophalangeal Joints:** These joints are classified as hinge joints, which allow movement in one plane (flexion and extension). Thus, they are not pivot joints.
- **Ankle Joints:** The ankle is primarily a gliding joint, allowing for limited movement between the bones of the lower leg and the foot. Hence, it is not a pivot joint.
- **Radial Ulnar Joints:** These joints are indeed pivot joints. They occur between the head of the radius and the radial notch of the ulna, allowing for rotational movement of the forearm.

3. **Conclusion:**
After analyzing all the options, the correct answer is the **Radial Ulnar Joints**, as they exemplify the characteristics of a pivot joint.

### Final Answer:
The example of a pivot joint is the **Radial Ulnar Joints**.

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