Which cavity includes both the cranial and spinal cavities?

The correct answer is the dorsal cavity, as it encompasses both the cranial cavity and the spinal cavity. The cranial cavity houses the brain, while the spinal cavity encloses the spinal cord, together forming a significant component of the central nervous system. The classification of these cavities under the dorsal cavity is based on their posterior positioning in the body, aligned along the back side (dorsum).

In contrast, the ventral cavity houses organs within the thoracic and abdominal regions, but it does not include the cranial or spinal cavities. The abdominopelvic cavity refers to a section of the ventral cavity and is specifically associated with the abdomen and pelvis, further excluding the cranial and spinal cavities. The thoracic cavity is a division of the ventral cavity containing the lungs and heart, and does not connect to the cranial or spinal regions. Therefore, the dorsal cavity correctly identifies the area that collectively includes the cranial and spinal cavities.