Joint between humerus and radio-ulna is
(a) Ball & socket
(b) Pivot
(c) Gliding
(d) Hinge

Options

A. Ball & socket
B. Pivot
C. Gliding
D. Hinge

Answer

To determine the type of joint between the humerus and the radio-ulna, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Bones Involved**: The question refers to the humerus (the upper arm bone) and the radio-ulna (the two bones in the forearm, namely the radius and ulna).

2. **Understand the Joint Location**: The joint between the humerus and the radio-ulna is located at the elbow. This is where the upper arm meets the forearm.

3. **Determine the Type of Joint**:
- The elbow joint allows for flexion and extension movements, which are characteristic of a specific type of joint.
- The options given are:
- (a) Ball & socket
- (b) Pivot
- (c) Gliding
- (d) Hinge

4. **Analyze Each Option**:
- **Ball & Socket**: This type of joint allows for rotational movement in multiple directions (e.g., shoulder joint). This is not applicable here.
- **Pivot**: This joint allows for rotation around a single axis (e.g., the joint between the first and second cervical vertebrae). This is not the case for the elbow.
- **Gliding**: This joint allows bones to glide past each other in a limited manner (e.g., joints in the wrist). This is not applicable to the elbow.
- **Hinge**: This joint allows movement primarily in one direction (flexion and extension), which is exactly how the elbow functions.

5. **Conclusion**: Based on the analysis, the joint between the humerus and the radio-ulna is classified as a **hinge joint**. Therefore, the correct answer is **(d) Hinge**.

### Final Answer:
The joint between the humerus and radio-ulna is (d) Hinge.