Which bone forms the back and base of the skull?

Which bone forms the back and base of the skull?

• A. Occipital bone
• B. Temporal bone
• C. Sphenoid bone
• D. Parietal bone

Answer: (A)

The bone that forms the back and base of the skull is the occipital bone. It sits at the posterior-inferior part of the cranium and makes most of the posterior cranial fossa, which is the base area at the back of the skull. A key feature is the foramen magnum, the large opening where the brainstem continues as the spinal cord. The occipital bone also has the occipital condyles that articulate with the first cervical vertebra, allowing head nodding. The external surface shows the external occipital protuberance and the nuchal lines for neck muscle attachments. The other bones listed contribute to various regions of the skull but not the back and base in the same way: temporal bones are on the sides and contribute to the base in parts, the sphenoid contributes to the middle and base anteriorly, and the parietal bones form the crown and sides rather than the back/base.

The bone that forms the back and base of the skull is the occipital bone. It sits at the posterior-inferior part of the cranium and makes most of the posterior cranial fossa, which is the base area at the back of the skull. A key feature is the foramen magnum, the large opening where the brainstem continues as the spinal cord. The occipital bone also has the occipital condyles that articulate with the first cervical vertebra, allowing head nodding. The external surface shows the external occipital protuberance and the nuchal lines for neck muscle attachments. The other bones listed contribute to various regions of the skull but not the back and base in the same way: temporal bones are on the sides and contribute to the base in parts, the sphenoid contributes to the middle and base anteriorly, and the parietal bones form the crown and sides rather than the back/base.