3. (Aeronautics) any structure corresponding to or resembling the keel of a ship, such as the central member along the bottom of an aircraft fuselage. 4. (Biology) biology a ridgelike part; carina. 5. a poetic word for ship.
Transverse colon and sigmoid colon. The transverse colon and the sigmoid colon have a mesentery (ie, transverse mesocolon and sigmoid mesocolon, respectively), but the ascending colon and descending colon are retroperitoneal, while the cecum is intraperitoneal but uses the mesentery of the ileum.
The sigmoid colon is a hollow tube approximately 2 Â½ inches (7 cm) in diameter and 16 inches (40 cm) long. A band of smooth muscle tissue running the length of the colon contracts to form many small pouches called haustra in the walls of the sigmoid colon....