Answer: It is the DORSAL BODYCAVITY that is completely surrounded by bones and provide very good protection to the structure it contains.
Explanation:
Body cavity is that the space that contain fluid in the animal body. Cavities house the organs and structures. The two largest body cavities are ventral and dorsal body cavities.
The dorsal body cavity consist of cranial and spinal cavities and they are completely surrounded by bones that provides protection for the structures it contain.
The ventral cavity consist of abdominopelvic and thorasic cavities. The ventral cavity and the organs it accomodate are lined by a thin covering of serosa membrane
