Which structure is not part of the axial skeleton?

The limb bones are not part of the axial skeleton because they belong to the appendicular skeleton. The axial skeleton consists of the skull, vertebral column, and ribs, which serve to support and protect the head, neck, and trunk of the body. In contrast, the appendicular skeleton includes the bones of the limbs and the girdles that attach the limbs to the axial skeleton. This distinction is essential for understanding the organization of the human skeleton and the specific roles each component plays in movement and support.