Final answer:
The ascending colon is retroperitoneal and begins at the ileocecal valve, the transverse colon is intraperitoneal and begins at the right colic flexure, the sigmoid colon is intraperitoneal and ends at the rectum, and the descending colon is retroperitoneal and begins at the left colic flexure.
Step-by-step explanation:
Direct answer in 2 lines:
- The ascending colon originates at the ileocecal valve and is retroperitoneal.
- The transverse colon originates at the right colic flexure and is intraperitoneal.
- The sigmoid colon terminates at the rectum and is intraperitoneal.
- The descending colon originates at the left colic flexure and is retroperitoneal.
Explanation in 200 words:
The colon is a part of the large intestine and is subdivided into several segments, each with unique anatomical features and positions within the abdominal cavity. The initial section of the colon, right after the ileocecal valve (where the small intestine ends), is the ascending colon. This portion moves upward on the right side of the abdomen and is retroperitoneal, meaning it lies behind the peritoneum, the lining of the abdominal cavity. It continues to the right colic flexure, also known as the hepatic flexure, where it sharply turns to become the transverse colon. This section is intraperitoneal and is suspended by the mesocolon to the posterior abdominal wall.
After reaching the left colic flexure or splenic flexure, the colon then becomes the descending colon. Like the ascending colon, the descending portion is also retroperitoneal as it goes down the left side of the abdomen. Lastly, the colon transitions into the sigmoid colon, an intraperitoneal S-shaped section that terminates at the rectum, leading eventually to the anus.