How many major closed cavities does the human body have?

• A. One
• B. Two
• C. Three
• D. Four

Answer: (B)

The main concept is that the body has two large closed spaces that are protected and not open to the outside: the dorsal and the ventral cavities. The dorsal cavity runs along the back and contains the brain (in the cranial part) and the spinal cord (in the vertebral part). The ventral cavity sits in the front and is separated from the dorsal by the diaphragm; it’s further divided into the thoracic cavity (which holds the heart and lungs) and the abdominopelvic cavity (which houses most of the abdominal and pelvic organs). So, while you can describe several smaller regions within these cavities, there are two major closed cavities in the body.