Jejunum and ileum

Some key facts about the anatomy of the jejunum and ileum:

  • Total length: 6-7 meters together.
  • Plays an essential role in nutrient absorption.
  • There is no clear division between the jejunum and ileum. Changes between both are gradual.
  • If one draws a line from the right upper corner of the abdomen to its left lower corner, the jejunum generally lies above the line, but the ileum below it.
  • Both jejunum and ileum contain permanent circular folds (also called plicae circulares or valvular conniventes) projecting into the intestinal lumen.



  • Mostly located in the left upper quadrant, makes ~2/5 of the total length of the small intestine.
  • Has a thicker wall than the ileum due to the higher circular folds.



  • Mostly located in the right lower quadrant and connects to the cecum at the ileocecal junction.
  • Has a thinner wall in comparison to the jejunum.
  • Further in its mesentery (“creeps” onto the tube). 
  • The folds of the ileum are sparse and low, but it has distinctive patches of lymphoid tissue (Peyer’s patches) that are often several centimeters long.