What is included in the axial skeleton?

The axial skeleton is a key component of the human skeletal system, composed of the bones that form the central axis of the body. This includes the skull, which houses and protects the brain, the rib cage, which safeguards the thoracic organs and provides structural support, and the spine (vertebral column), which supports the head and provides a flexible yet stable connection throughout the body.

The other choices pertain to different parts of the skeletal system. The shoulder and pelvic girdles mentioned in the first option are part of the appendicular skeleton, which connects the limbs to the axial skeleton. The arms and legs referenced in the third choice are also part of the appendicular skeleton, as they are the limbs that extend from the central axis. Similarly, the hands and feet mentioned in the fourth choice are components of the appendicular skeleton. Thus, the skull, rib cage, and spine distinctly define the axial skeleton, while the other options represent the structures associated with the limbs and girdles.