c. The ileum is the third, or distal, portion of the small intestine. It is about 16
feet in length and constitutes about three-fifths of the small intestine. It begins at the
distal end of the jejunum and terminates at the ileocecal valve, which guards the
opening between the ileum and the proximal portion of the large intestine. The ileum
and the jejunum are coiled throughout the central and lower portions of the abdominal
Figure 3-5. The duodenum in relation to the accessory organs of digestion.