Which of the following bones is the only bone in the body that is not in contact with another bone?
(a) Ethmoid bone
(b) Atlas
(c) Hyoid bone
(d) Floating ribs

Options

A. Ethmoid bone
B. Atlas
C. Hyoid bone
D. Floating ribs

Explanation

To solve the question of which bone in the body is the only one that is not in contact with another bone, we can analyze each option provided:

1. **Ethmoid bone**: This bone is located in the skull and is part of the nasal cavity structure. It is in contact with other bones in the skull, such as the frontal and sphenoid bones.

2. **Atlas**: The atlas is the first cervical vertebra in the spine. It is in contact with the occipital bone of the skull above and the axis (the second cervical vertebra) below.

3. **Hyoid bone**: The hyoid bone is located in the neck and is unique because it does not articulate with any other bone. Instead, it is suspended by ligaments and muscles, serving as an attachment point for various muscles of the head and neck.

4. **Floating ribs**: Floating ribs are the last two pairs of ribs in the rib cage. While they do not attach to the sternum, they are still connected to the vertebrae in the spine.

Based on this analysis, the only bone that is not in contact with any other bone in the body is the **hyoid bone**.

**Final Answer**: (c) Hyoid bone

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