The joint of radio-ulna with the upper arm is

Options

A. hinge joint
B. socket joint
C. pivot joint
D. none of these.

Explanation

### Step-by-Step Solution:

1. **Understanding Joints**: A joint is a point where two bones meet, allowing for movement. The type of joint determines the range and direction of movement.

2. **Identifying the Joint in Question**: The question specifically asks about the joint between the radius and ulna with the upper arm, which is the humerus. This joint is commonly referred to as the elbow joint.

3. **Types of Joints**: There are several types of joints in the human body, but the most relevant for this question are:
- **Synovial Joints**: These joints have a fluid-filled cavity (synovial fluid) that allows for considerable movement.
- **Hinge Joints**: These allow movement in one direction, similar to the way a door opens and closes.
- **Ball and Socket Joints**: These allow for rotational movement in multiple directions (e.g., shoulder and hip joints).
- **Pivot Joints**: These allow for rotational movement around a single axis (e.g., the joint between the first two vertebrae).

4. **Determining the Type of Joint at the Elbow**: The elbow joint, where the humerus connects with the radius and ulna, is a synovial joint. More specifically, it is classified as a hinge joint because it allows for bending and straightening (flexion and extension) but does not allow for movement in the opposite direction (like a door).

5. **Conclusion**: Therefore, the joint of the radius and ulna with the upper arm (humerus) is classified as a **hinge joint**.

### Final Answer:
The joint of the radio-ulna with the upper arm is a **hinge joint**.

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