Anatomy of the Colon
The colon, also known as the large intestine or large bowel, is made up of muscle and is the distal part of the gastrointestinal tract. (1) It’s a 150 cm tube that starts from the cecum and ends in the anal canal, consisting of the following regions: (2,3)
1. Cecum
- Position: The cecum is a large tubelike part of the colon attached to the ileum, the final part of the small intestines, via the ileocecal valve.
- Function: It absorbs water and electrolytes that aren’t digested and absorbed in the small intestines and mixes its contents with mucus.
2. Ascending Colon (Traveling Up)
- Position: The ascending colon is a retroperitoneal structure that extends upward to the right side of the abdomen.
- Function: This part absorbs the remaining water and essential nutrients, creating a solid stool.
3. Transverse Colon (Traveling horizontally)
- Position: The horizontal, intraperitoneal part of the colon extends from the right colic flexure to the spleen, creating a 90-degree turn. It is the least fixed and most variable part of the colon.
- Function: The transverse colon is essential for further absorption and storage of the stool.
4. Descending Colon (Traveling Down)
- Position: The descending colon extends inferiorly toward the pelvis and is located on the left side of the abdomen, passing over the lateral border.
- Function: It passes stool from the transverse colon to the sigmoid part, where it will eventually be emptied into the rectum.
5. Sigmoid Colon
- Position: The sigmoid colon forms a 40 cm long, S-shaped segment located in the left lower part of the abdomen.
- Function: This final part of the colon stores stool wastes to be expelled from the body through the rectum.
Functions of the Colon (4)
1. Water and Electrolytes Absorption
The primary function of the colon is to absorb the remaining water, nutrients, and vitamins from indigestible residues of food from the small intestines, solidifying it into the stool to be ready to be expelled from the body.
2. Hydration
The colon helps absorb and retain water, which helps in maintaining the body’s hydration levels.
3. Storage of Beneficial Bacteria
The colon consists of live, beneficial microorganisms that digest food and prevent the growth of pathogenic bacteria, maintaining the gut microbiota.
4. Production of Mucus
The colon produces a lubricating agent called mucus to moisturize its lining and create a smooth pathway for stools to pass.
Signs of Pain in the Colon
Various underlying causes can cause pain in the colon, which can be mild, moderate, or severe. Understanding colon conditions and their associated symptoms is crucial for optimal management. These symptoms include the following: (5,6)
1. Abdominal Pain
Irritable bowel syndrome (IBS), irritable bowel disease (IBD), colitis, and other digestive conditions can cause sharp abdominal pain and cramping.
2. Bloating
The production of gas, bloating, and feeling uncomfortably full can be signs of blockage or inflammation in the colon.
3. Bowel Movement Changes
Infections, inflammations, colon conditions, or colorectal cancer can cause chronic diarrhea, constipation, or unexpected sudden changes in bowel function.
4. Blood in Stool
Finding blood in stool is a concerning indicator of an underlying cause, such as hemorrhoids, anal fissures, or colorectal cancer.
5. Fatigue and Malaise
General fatigue and muscle weakness can occur due to colon conditions, such as Crohn’s disease or ulcerative colitis, which cause blood loss and essential nutrient deficiencies.
References
- https://fascrs.org/patients/diseases-and-conditions/a-z/the-colon-what-it-is,-what-it-does
- https://teachmeanatomy.info/abdomen/gi-tract/colon/
- https://www.ncbi.nlm.nih.gov/books/NBK507857/#:~:text=The%20role%20of%20the%20ascending,be%20emptied%20into%20the%20rectum.
- https://www.cancer.gov/publications/dictionaries/cancer-terms/def/colon
- https://my.clevelandclinic.org/health/body/22134-colon-large-intestine
- https://www.healthline.com/health/pain-in-colon
