Application Potential of Polymeric Nanoconstructs for Colon-Specific Drug Delivery

Parts of the Colon

The large intestine is approximately 1.5 m and divided into various segments such as caecum, ascending colon, hepatic flexure, transverse colon, splenic flexure, appendix, descending colon, sigmoid colon, rectum and anus. The caecum has out-pouching in the interior; extends beyond ileocaecal junction and is in continuation with the ascending colon superiorly. There is a narrow diverticulum called vermiform appendix at the angle between the caecum and terminal part of ileum. The colon is covered by a pink lining known as mucosa. The ascending colon transcends upwards from the caecum and it bends to the left at the hepatic flexure to form transverse colon. Hepatic flexure is located inferior to the lobe of the liver (Mitchell, Vogl, & Adam, 2009). Splenic flexure is located just inferior to the spleen, higher and more posterior than the right colic flexure and is connected to the diaphragm by phrenicocolic ligament (Mitchell, R. D., Vogl, A. W., & Adam, W. M., 2009). The descending colon transcends down from the left side of the abdominal cavity then folds towards the midline. Sigmoid colon is a S-shaped curve situated in the pelvic region near the left iliac crest which continues downwards to form the rectum.