the spleen is associated with the left kidney and splenic flexure of the colon, while medially the stomach and pancreas are intimately associated with spleen. The spleen is stabilized in its left upper quadrant locations by five peritoneal attachments termed ligaments. Medially the splenogastric ligament contains the short gastric vessels, while the splenophrenic ligament runs from the left hemidiaphragm to the superior pole of the spleen. The spleno-colic and splenoomental ligaments fix the lower splenic pole with the splenic flexure of the colon and the left lateral aspect of the omentum, respectively. The splenorenal ligament, an anterior traversing segment of the posterior peritoneum, envelops the splenic vessels and tail of the pancreas (Fig. 13-1).

The spleen receives its arterial supply from the splenic artery, a branch of the celiac axis. The splenic artery generally branches into two to four vessels that then enter the spleen at the hilum. These main splenic artery tributaries branch into the trabecular arteries which then branch into the central arteries,

Figure 13-1 Anatomy of the spleen and surrounding organs. (Source: Adapted from Zollinger RM, Zollinger RM Jr. Atlas of Surgical Operations, 7th ed. New York: McGraw-Hill, 1993.)

surrounded by white pulp, that send radial branches into the red pulp consisting of macrophage-lined sinusoids. The sinusoids coalesce into venules that merge to form the splenic vein. The splenic vein courses on the caudal aspect of the pancreas to join the superior mesenteric vein at the level of the head of the pancreas to form the portal vein. Because of the portal venous drainage of the spleen, portal hypertension is one of the most common causes of splenomegaly. The short gastric vessels also provide arterial supply and venous drainage, which provides a conduit between the portal and systemic circulation.

Microscopically and functionally, the spleen is divided into two zones, the white pulp, surrounding the central arteries which is composed of T and B lymphocytes and the red pulp which is predominantly composed of cells of the reticuloendothelial system. The white pulp is comprised of the periarterial lymphatic sheaths containing T lymphocytes and the more peripheral germinal centers composed of B lymphocytes and antibody-producing plasma cells. The red pulp is composed of vascular sinusoids separated by splenic cords (cords of Billroth). The splenic cords contain macrophages with long dendritic processes that create a labyrinth-like network, through which blood cells slowly percolate (Fig. 13-2).

Blood Pressure Health

Blood Pressure Health

Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...

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