Which one is a ball and socket joint

Options

A. Knee joint
B. Elbow joint
C. Humerus and pectoral girdle
D. Skull and atlas.

Answer

**Step-by-Step Solution:**

1. **Understanding Joint Types**:
- Begin by identifying the types of joints. A ball and socket joint allows for a wide range of movement, including rotation. It consists of a spherical head of one bone fitting into a cup-like cavity of another bone.

2. **Analyzing the Options**:
- The options provided are:
- A) Knee joint
- B) Elbow joint
- C) Humerus and pectoral girdle
- D) Skull and atlas

3. **Evaluating Each Option**:
- **Knee Joint**: This is a hinge joint, allowing movement primarily in one direction (flexion and extension). Therefore, it is not a ball and socket joint.
- **Elbow Joint**: This is also a hinge joint, allowing flexion and extension. Thus, it is not a ball and socket joint.
- **Humerus and Pectoral Girdle**: This forms the shoulder joint, which is a classic example of a ball and socket joint. The head of the humerus fits into the shallow socket of the scapula (pectoral girdle), allowing for a wide range of motion.
- **Skull and Atlas**: This joint allows for nodding and rotation of the head but is classified as a pivot joint, not a ball and socket joint.

4. **Conclusion**:
- Based on the analysis, the correct answer is **C) Humerus and pectoral girdle**, as it forms a ball and socket joint.

---