Which bone forms the back of the skull?

The occipital bone is the correct answer because it is the bone that forms the posterior aspect of the skull. It is situated at the lower back part of the cranial cavity and comprises the base and back of the skull. One of its key features is the foramen magnum, a large opening through which the spinal cord passes to connect with the brain. This bone plays a crucial role in protecting the brain and supporting the structure of the skull.

In contrast, the temporal bone is located on the sides and base of the skull, involved in housing the structures of the ear and contributing to the sides of the cranium. The sphenoid bone, often described as the "keystone" of the skull, is situated in the middle and contributes to the floor of the cranium and the eye sockets. Lastly, the parietal bones form the sides and roof of the skull but do not encompass the back portion. This anatomical distinction clearly illustrates why the occipital bone is recognized specifically as the bone forming the back of the skull.