The Spleen

Spleen

The spleen is the largest organ in the immune system. Located in the left upper abdomen, behind the stomach and under the ribs, the spleen is  commonly fist-shaped, purple, and about 4 inches long in adults. Because the spleen is protected by the rib cage, you can’t easily feel it unless it’s abnormally enlarged.

These are links to some web sites with more information about the spleen:

Children’s Hospital of Pittsburgh

Wikipedia

WebMD