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.
See Article History. Sigmoid colon, a terminal section of the large intestine that connects the descending colon to the rectum; its function is to store fecal wastes until they are ready to leave the body. The sigmoid colon derives its name from the fact that it is curved in the form of an S (Greek sigma: Ï). Its size depends upon the amount of waste material in it, but when contracted its diameter is only about one inch (2.5 centimetres). The internal surface of the sigmoid colon is similar to that of the rest of the large intestine. The smooth mucous membrane lining secretes mucus and enzymes, and the liningâs surface cells can absorb fluids. Most of these activities occur, however, higher up in the intestinal tract.