Which one of the following bones is not the part of axial skeleton ?

Options

A. Hyoid bone
B. Sacrum
C. Sphenoid bone
D. Clavicle

Answer

**Step-by-Step Solution:**

1. **Understand the Axial Skeleton**: The axial skeleton consists of the bones that form the long axis of the body. This includes the skull, vertebral column, ribs, and sternum.

2. **Identify the Options**: The question provides four options. We need to evaluate each one to determine if it is part of the axial skeleton or not.

3. **Evaluate Each Option**:
- **Option A: Hyoid Bone**: This bone is located in the neck and supports the tongue. It is considered part of the axial skeleton.
- **Option B: Sacrum**: This is part of the vertebral column, which is included in the axial skeleton.
- **Option C: Sphenoid Bone**: This bone is part of the skull and is also included in the axial skeleton.
- **Option D: Clavicle**: The clavicle, or collarbone, is part of the pectoral girdle and serves as an attachment for the upper limbs. It is not part of the axial skeleton; instead, it belongs to the appendicular skeleton.

4. **Conclusion**: Since the clavicle is the only bone listed that is not part of the axial skeleton, the correct answer is **Option D: Clavicle**.