What is the structure that suspends the small intestine from the posterior body wall?

The correct answer is mesentery, which is a double layer of peritoneum that serves to anchor and support the small intestine to the posterior abdominal wall. The mesentery contains blood vessels, lymphatics, and nerves that supply the intestines, making it essential for both structural support and the transportation of nutrients. By providing this connection, the mesentery allows the small intestine to maintain its position while still permitting the necessary mobility for digestion and absorption.

The peritoneum, while involved in this structural support, refers more generally to the serous membrane that lines the abdominal cavity and covers the abdominal organs, not specifically to the supportive structure for the small intestine. The parietal pertains to the outer wall of a body cavity, and the cell membrane is a microscopic structure that surrounds individual cells; neither is relevant in the context of suspending bodily organs.