Transverse Colon

Overview

The transverse colon is a major segment of the large intestine, situated between the ascending colon and the descending colon. It is the longest and most mobile part of the colon, playing a key role in the absorption of water, electrolytes, and the final stages of nutrient digestion. The transverse colon is also involved in the movement and storage of fecal material before it moves to the rectum for excretion.

Location

The transverse colon is located in the upper abdomen and extends across the body from right to left. Specifically, it:

• Begins at the hepatic flexure (right colic flexure), where it transitions from the ascending colon

• Passes horizontally across the abdomen, just below the stomach and diaphragm, and reaches the splenic flexure (left colic flexure), where it transitions into the descending colon

• Is suspended from the posterior abdominal wall by the mesocolon, a peritoneal fold

• Is positioned above the small intestine and below the liver and spleen

Structure

The transverse colon has several structural features that contribute to its function:

• Length: Approximately 45–60 cm long, depending on individual anatomical variations

• Shape: Arises at a right angle from the ascending colon and curves horizontally across the abdomen to the left side

• Wall composition: The transverse colon, like other parts of the large intestine, has four layers: mucosa, submucosa, muscularis externa (with the outer longitudinal muscle forming the teniae coli), and serosa

• Haustra: The colon’s characteristic sacculations (pouches) are more pronounced in the transverse colon, formed by the contraction of the teniae coli

• Vascular supply: Blood is supplied by branches of the superior mesenteric artery (SMA), including the middle colic artery

• Lymphatic drainage: Drained by the mesenteric lymph nodes along the vessels

Function

The transverse colon serves several critical functions within the digestive system:

• Absorption: Absorbs water, electrolytes, and some remaining nutrients, transforming liquid chyme from the small intestine into semi-solid stool

• Storage: Acts as a temporary storage site for fecal material before it moves to the descending colon and rectum for elimination

• Fermentation: Hosts a large microbial community that ferments undigested carbohydrates and produces gases and short-chain fatty acids

• Conduction: Facilitates the movement of contents toward the rectum via peristalsis and mass movements

Physiological Role(s)

The transverse colon plays a key role in overall digestive function:

• Fluid and electrolyte balance: It reabsorbs the majority of water and electrolytes from the fecal material, helping maintain hydration and proper electrolyte levels in the body

• Microbial digestion: Ferments complex carbohydrates, fibers, and other indigestible materials, producing short-chain fatty acids that provide energy for the body

• Regulation of motility: The transverse colon is involved in the movement of food remnants through the large intestine, helping regulate the frequency and timing of bowel movements through coordinated peristaltic waves and mass movements

Clinical Significance

The transverse colon is associated with several clinical conditions, which can be diagnosed and treated through imaging and other diagnostic techniques:

• Colorectal cancer: The transverse colon is a common site for the development of adenocarcinoma, which may present with symptoms like abdominal pain, changes in bowel habits, or rectal bleeding

• Diverticulosis: The formation of diverticula (pouches) in the colon wall, more common in the sigmoid colon but can also affect the transverse colon, potentially leading to diverticulitis

• Colonic volvulus: The transverse colon can become twisted in a condition called volvulus, leading to obstruction, ischemia, and bowel perforation if untreated

• Chronic constipation: Dysfunctional peristalsis in the transverse colon may lead to delayed stool movement, causing constipation and discomfort

• Inflammatory bowel disease (IBD): Conditions like ulcerative colitis or Crohn’s disease can affect the transverse colon, causing inflammation, ulcers, and pain

• Radiological imaging: The transverse colon is frequently evaluated using techniques such as barium enema, CT scan, and colonoscopies to diagnose disorders like cancer, diverticulosis, and colitis

Treatment for conditions affecting the transverse colon may involve medications, dietary changes, or surgical interventions such as resection, stenting, or colostomy in severe cases.