Spleen

The spleen is the larget primary lymphoid organ found on the left side of the abdomen inferior to the diaphragm, in the peritoneal cavity.

The functions of the spleen are: immune surveillance, proliferation and maturation of lymphocytes and degradation of senescent and damaged erythrocytes

The spleen is underneath the left part of the diaphragm, and has a smooth, convex surface that faces the diaphragm, the diaphragmatic surface of the spleen. It is underneath the ninth, tenth, and eleventh ribs.

The other side, the visceral surface of the spleen, is divided by a ridge into two regions: an anterior gastric portion, and a posterior renal portion:

• The gastric surface (gastric impression of spleen) is directed forward, upward, and toward the middle, is broad and concave, and is in contact with the posterior wall of the stomach and the left colic flexure to form the colic impression of the spleen. Below this, the spleen is in contact with the tail of the pancreas, forming the pancreatic impression of spleen. On the gastric surface is located the hilum of the spleen, the point of attachment for the gastrosplenic ligament, and the point of insertion for the splenic artery and splenic vein.

• The renal surface (renal impression of spleen) is directed medialward and downward. It is somewhat flattened, considerably narrower than the gastric surface, and is in relation with the upper part of the anterior surface of the left kidney and occasionally with the left adrenal gland.

The spleen has two (or three) borders :

• The superior border that bounds the gastric impression of spleen

• The inferior border that bounds renal impression of spleen

• An anterior border is described by some authors, bounding the colic impression of the spleen

The spleen has two extremities, an anterior and a posterior.

There are four ligaments attached to the spleen: gastrosplenic ligament, splenorenal ligament, splenocolic ligament, and phrenicocolic ligament.