Answers. Best Answer: The abdominopelvic and thoracic cavities are subdivisions of the ventral body cavity. The cranial and spinal cavities are parts of the dorsal body cavity. The cranial body cavity is totally surrounded by bone ...he abdominopelvic and thoracic cavities are subdivisions of the __(1)__ body cavity; the cranial and spinal cavities are parts of the __(2)__ body cavity. The __(3)__ body cavity is totally surrounded by bone and provides very good protection to the structures it contains. Add your answer. Source.