17.Large intestine

• Divisions of the large intestines

  • Cecum
  • Appendix
  • Colon - ascending
  • Colon - transverse
  • Colon - descending
  • Colon - sigmoid
  • Rectum
  • Anal canal
• Taenia coli


  • Three thickened bands of muscles
• Haustra


  • Sacculations
• Appendices epiploicae


  • Fatty tags
• Parts of the colon

  • Transverse colon
  • Sigmoid colon
  • Descending colon
  • Rectum
  • Ascending colon
  • Anal colon
• Transverse colon length: 38 cms/ 15 inches
• Sigmoid colon length: 25–38 cms/ 10-15 inches
• Descending colon length: 25 cms/ 10 inches
• Rectum length: 13 cms/ 5 inches
• Ascending colon length: 13 cms/ 5 inches
• Anal colon length: 4 cms/ 1 and 1⁄2 inch
• Cecum


  • Blind-ended pouch situated in the R iliac fossa
  • Around 2 I/2 inches (6 cms) long
  • With peritoneum
  • Movable
  • No mesentery
• Blood supply to cecum

  1. Supplied by anterior / posterior cecal A from ileocolic A – SMA

  2. Drained by anterior / posterior cecal V to ileocolic V – SMV
• Appendix


  • Wormlike, blind intestinal diverticulum
  • Short triangular mesentery - mesoappendix
  • 3 - 5 inches (6 -10 cms) in length
  • Base is attached to the posteromedial of cecum about 1 inch below the ileocecal junction
  • Lies in the R iliac fossa
• Locating the appendix


  1. Identify the teniae coli of the cecum

  2. Trace them to the base of the appendix
• Relation of appendix to anterior abdominal wall

  Base is situated one third of the way up the line joining the right ASIS to the umbilicus / McBurney point
• Inside the abdomen, the base of the appendix is easily found by identifying the teniae coli of the cecum and tracing them to the base of the appendix
• Positions where the appendix may be found

  • Retrocecal
  • Pelvic
  • Ileocecal
  • Subcecal
• Appendix Blood Supply


  • Supplied by appendicular A from ileocolic A
  • Drained by appendicular V to the posterior cecal V - SMV
• Appendicitis


  • May become inflamed as a result of either an obstruction by a stool, which forms a fecalith (common in adults) or hyperplasia of its lymphatic tissue (common in children)
• Ascending Colon


  • Passes superiorly on the R side from cecum to the R lobe of liver where it turns to the L at R colic / hepatic flexure
  • About 5 inches/ 13 cms long
  • Supplied by ileocolic and right colic A from SMA
  • Drained by ileocolic and right colic V to SMV
• Transverse Colon


  • About 15 inches (38 cms) longest, largest & most mobile
  • Occupies the umbilical region, crosses from the R colic flexure to the L colic / splenic flexure
  • With transverse mesocolon which suspend the transverse colon from Ant border of the pancreas
  • Supplied mainly by middle colic A from SMA, also by Right colic from SMA and L colic from IMA
  • Drained by superior & inferior mesenteric V
• Descending Colon


  • Approximately 10 inches (25 cms) long
  • Passes retroperitoneally from the L colic flexure into the L iliac fossa where it continues with sigmoid colon
  • Supplied by L colic & sigmoid A from IMA
  • Drained by IMV
• Sigmoid Colon


  • S-shaped loop
  • Approximately 10-15 inches (25-38 cm) long
  • Extends from the iliac fossa to the 3rd sacral vertebra - rectum
  • With fan-shaped sigmoid mesocolon
• Anterior relations of sigmoid colon

  In males - urinary bladder

  In females - uterus and vagina
• Posterior relations of sigmoid colon

  Rectum and sacrum
• Blood supply of sigmoid colon

  Supplied by sigmoid artery from inferior mesenteric artery

  Drained by inferior mesenteric vein
• Sigmoid volvulus


  • Twists around the sigmoid mesocolon and may become obstructed
  • Patients may experience left sided colicky pain, abdominal distention and hematochezia as a result of compromise of the sigmoid arteries
• Diverticulosis


  Refers to diverticula that are not inflamed
• Diverticulitis


  • Inflamed
  • If ruptured, contents may irritate the parietal peritoneum, resulting in pain that is localized to the LLQ
  • Patients may have hematochezia