A body cavity is a space or compartment in the body that is lined with cells and contains fluid. Body cavities can also be potential spaces that normally contain small amounts of fluid but can become enlarged due to physiological or pathological causes. The cell layer and fluid serve as a protection for the organs that are located inside a body cavity. There are multiple cavities inside the human body, and several can be grouped together. Such is the case of the dorsal body cavity. The dorsal body cavity houses the brain and spinal cord via the cranial cavity and the vertebral cavity. The thoracic cavity houses the lungs and heart (among other organs and structures) via the mediastinum and pleural cavities. The abdominopelvic cavity houses the abdominal and pelvic organs. Together, the thoracic cavity and the abdominopelvic cavity are known as the ventral body cavity.