Spleen
The spleen is an organ found in all vertebrates. Similar in structure to a large lymph node, it acts primarily as a blood filter. The word spleen comes from Ancient Greek σπλήν (splḗn).
The spleen plays important roles in regard to red blood cells (erythrocytes) and the immune system. It removes old red blood cells and holds a reserve of blood, which can be valuable in case of hemorrhagic shock, and also recycles iron. As a part of the mononuclear phagocyte system, it metabolizes hemoglobin removed from senescent red blood cells (erythrocytes). The globin portion of hemoglobin is degraded to its constitutive amino acids, and the heme portion is metabolized to bilirubin, which is removed in the liver
SPLEEN ANATOMY
- dimensions
- soft , vascular and purple in colour
- average
- 1 inch or 2.5cm thick
- 3 inches or 7.5 cm broad
- 5 inches or 12.4 cm long
- 7 ounces in weight
- related to 9 and 11 ribs
- mnemonic
- 1,3,5,7,9,11
- external features
- ends
- anterior or lateral end
- expanded more like a border
- posterior or medial end
- rounded
- rests of upper pole of left kidney
- borders
- superior
- notched near anterior end
- inferior
- rounded
- intermediate
- rounded and directed to right
- surfaces
- diaphragmatic
- convex and smooth
- visceral
- concave and triangular
- angles
- anterobasal
- spleen in enlarged it is called
- clinical angle of spleen
- posterobasal
- junction of inferior border
- with lateral or anterior end of spleen
- hilum
- arterial supply
- supplied by splenic artery
- largest branch of celiac trunk
- tortous in its course to allow movements for spleen
- passes through lineorenal ligament to reach hilum of spleen
- it gives five more branches here
- with in spleen it divides repeatedly to form straight vessels called pencilli
- lymphatic drainage
- a few lymphatics from connective tissue of capsule
- drain in to panreaticosplenic lymph node
- functions of spleen
- phagocytosis
- hemopoiesis
- immune response
- increased lymphopoiesis
- storage of rbc
- development
- from mesoderm
- cephalic part of left layer of dorsal mesogastrium
- development occurs during 6 th week of intrauterine life
- many nodules develop fuse to form lobulated spleen
- if they fail to fuse they form
- accesory spleens
- location
- wedge shaped organ
- tetrahedral in shaoe
- lies in hypogastrium
- partly in epigastrium
- wedged in between fundus of stomach and diaphragm
- position
- along long axis of 10th rib
- directed forwards , downwards and laterally
- 45 degree with horizontal plane
- relations
- peritoneal relation
- gastrosplenic ligament
- extends from hilum of spleen to greater curvature of stomach
- contains short gastric vessels
- lienorenal ligament
- hilum of spleen to anterior surface of left kidney
- contains tail of pancreas
- phrenicocolic ligament
- not attached to spleen
- fold of peritoneum
- from splenic flexure of colon to diaphragm
- opposite 11th rib in midaxillary line
- also called as sustentaculum lienis
- visceral relation
- visceral surface
- gastric impression
- fundus of stomach
- lies b/w superior and intermediate borders
- largest and most concave impression
- renal impression
- left kidney
- lies b/w inferior and intermediate borders
- colic impression
- splenic flexure of colon
- occupies a triangular area adjoining anterior end of spleen
- lower part related to phrenicocolic ligament
- pancreatic impression
- for tail of pancreas
- hilum
- lies on inferomedial part of gastric impression
- transmits splenic vessels and nerves
- diaphragmmatic surface
- venous drainage
- splenic vein is formed at hilum
- it has a straight course
- joins superior mesenteric vein
- to form portal vein
- nerve supply
- sympathetic fibres are derived from celiac plexus
- vasomotor in nature
- supply smooth muscle in capsule