Spleen is a lymphatic organ that filters blood and supports immune defence, the body’s recognition and removal of foreign material. It lies in the upper left abdomen, beneath the diaphragm and behind the stomach. Unlike lymph nodes, which filter lymph returning from tissues, the spleen acts directly on circulating blood.
Where is the spleen located?
The spleen occupies the left hypochondriac region, the upper left area of the abdomen beneath the ribs. Its long axis follows approximately the direction of the tenth rib, and it lies deep to the ninth to eleventh ribs. The diaphragm, the muscular partition between the chest and abdomen, separates it from the left lung and the overlying chest wall.
The stomach lies in front of and towards the inner side of the spleen. The left kidney is behind and towards its inner side, while the left colic flexure—the bend where the transverse colon becomes the descending colon—lies below it. The tail of the pancreas approaches the spleen at its vessel-entry region.
What are the surfaces and hilum of the spleen?
The spleen has a smooth, convex outer surface and an inward-facing visceral surface, meaning the surface related to neighbouring abdominal organs. The named gastric, renal and colic surfaces are areas of this visceral surface. These relationships help explain its shape.
| Surface | Main anatomical relationship |
|---|---|
| Diaphragmatic surface of spleen | Faces the diaphragm and follows its curved contour. |
| Gastric surface of spleen | Faces the stomach. |
| Renal surface of spleen | Relates to the left kidney. |
| Colic surface of spleen | Relates to the left colic flexure. |
The hilum of spleen is a groove on the visceral surface where blood vessels, lymphatic vessels and nerves enter or leave. The pancreatic tail lies close to this region. The superior border, meaning the upper edge, commonly bears notches that help distinguish the spleen from neighbouring structures.
What holds the spleen in position?
The spleen is almost completely covered by peritoneum, the thin membrane that lines the abdominal cavity and covers many abdominal organs. This covering is absent at the hilum. Folds of peritoneum connect the spleen to nearby structures and provide routes for vessels.
- The gastrosplenic ligament connects the spleen to the stomach and carries the short gastric and left gastro-omental vessels, which supply parts of the stomach.
- The splenorenal ligament connects the spleen to the posterior abdominal wall near the left kidney and contains the main splenic vessels and the pancreatic tail.
These ligaments are peritoneal folds rather than the dense bands that connect bones at joints. Below the spleen, the phrenicocolic ligament, a fold between the diaphragm and colon, provides support without attaching directly to the spleen.
How is the spleen structured internally?
Beneath its peritoneal covering, the spleen has a capsule of fibrous connective tissue. Trabeculae, inward extensions of this capsule, form a supporting framework and carry vessels into the organ. Its working tissue is called splenic pulp and is divided into red pulp and white pulp.
Red pulp contains blood-filled channels called sinusoids and tissue between them called splenic cords. This arrangement brings circulating blood into contact with cells that remove ageing red blood cells and other material. Red blood cells are the cells that carry oxygen in the bloodstream.
White pulp consists of lymphoid tissue, tissue rich in immune cells called lymphocytes, arranged around small arteries. It supports immune responses to substances arriving in the blood. Red and white pulp are interspersed rather than arranged as a simple outer layer and inner core.
What are its blood supply, nerve supply and lymph drainage?
The splenic artery arises from the coeliac trunk, an arterial branch of the abdominal aorta that supplies upper abdominal organs. It follows a winding course along the upper border of the pancreas before dividing into branches near the hilum. These branches enter the spleen and distribute blood through its internal framework.
The splenic vein leaves the hilum and passes behind the pancreas. It joins the superior mesenteric vein behind the neck of the pancreas to form the portal vein. The portal vein carries blood from abdominal digestive organs and the spleen to the liver.
Nerve fibres reach the spleen through the coeliac plexus, a network of nerves around the coeliac trunk, and follow the splenic artery. The principal supply is sympathetic: part of the involuntary nervous system that regulates functions such as blood vessel tone.
Lymph, fluid collected from tissues by lymphatic vessels, drains from the spleen towards pancreaticosplenic lymph nodes along the splenic vessels. It then passes towards coeliac lymph nodes near the coeliac trunk. These nodes are small lymph-filtering structures, distinct from the spleen’s blood-filtering tissue.
What does the spleen do?
The spleen removes ageing or damaged red blood cells and helps recycle their components, including iron. It also supports immune recognition of foreign material carried in blood. These activities correspond broadly to the roles of red pulp and white pulp.
The spleen also holds a reserve of platelets, small blood components involved in clotting. Although blood passes through the spleen, it does not propel blood around the body; that is the heart’s role.
How can you explore the spleen in the 3D model?
In the 3D model next to this article, select the spleen, then rotate and zoom to change the viewing angle and scale. Isolate it to focus on the selected structure, or fade it to adjust its visibility without hiding it completely.
Switch layers on and off, and hide or isolate selected structures to adjust the view as you explore the model. Cut a section along the sagittal, coronal or transverse plane, or pull parts apart; rotate and zoom again to view the result from a different angle.