Ileum

The final, longest, and narrowest section of the small intestine. It is joined at its upper end to the jejunum and at its lower end to the large intestine (comprising the caecum, colon, and rectum). The function of the ileum is to absorb nutrients from food that has been digested in the stomach and the first 2 sections of the small intestine (the duodenum and the jejunum). Occasionally the ileum becomes obstructed, for example by pushing through a weakness in the abdominal wall (see hernia) or by becoming caught up with scar tissue following abdominal surgery (see adhesion). Other disorders of the ileum include Meckel’s diverticulum and diseases in which absorption of nutrients is impaired, such as Crohn’s disease, coeliac disease, tropical sprue, and lymphoma.