Spleen
Splen (lien)
Lymphatic & immuneLymphaticsAbdomenLeft side
- What it is
- A soft, dark-purple, fist-sized organ tucked under the left dome of the diaphragm behind the stomach, lying along the 9th-11th ribs and fully protected by the rib cage. Its smooth outer (diaphragmatic) surface is convex; the inner (visceral) surface is concave and carries the hilum where the splenic vessels enter. A thin fibrous capsule wraps it.
- Function
- Filters the blood: old and damaged red cells are destroyed by macrophages in the red pulp, while the white pulp mounts immune responses to blood-borne microbes.
- Size
- About 12 x 7 x 4 cm, 150 g (range 80-300 g); the "odd numbers" rule: 1 x 3 x 5 inches, 7 oz, ribs 9-11
- Clinical note
- The organ most often injured in blunt abdominal trauma; it can bleed massively and sometimes must be removed. After splenectomy, patients are vulnerable to encapsulated bacteria (pneumococcus, meningococcus, Haemophilus) and need vaccination. A normal spleen cannot be felt: it must enlarge 2-3 times to be palpable below the ribs.