1 by 3 by 5 inches, 7 ounces, between ribs 9 and 11
Mnemonic
The 1, 3, 5, 7, 9, 11 rule:
- 1 inch thick
- 3 inches wide
- 5 inches long
- 7 ounces in weight
- Lies against ribs 9 to 11
- Along the axis of the 10th rib, in the left hypochondrium
It is intraperitoneal, connected by the gastrosplenic ligament (short gastric and left gastroepiploic vessels) and the splenorenal ligament (splenic vessels and the tail of the pancreas).
The tail of the pancreas reaches the splenic hilum in most people, which is why it is injured in splenectomy and why a pancreatic tail tumour can present with splenic vein thrombosis and isolated gastric varices.
An enlarged spleen grows towards the right iliac fossa, moves with respiration, has a palpable notch and you cannot get above it, which distinguishes it from a kidney.
Expansion
- 1 x 3 x 5 inches in dimensions
- 7 ounces in weight (about 200 g)
- Lies deep to ribs 9 to 11, along the axis of the tenth rib
- 1 organ, with its long axis parallel to rib 10
The normal spleen is not palpable, it must enlarge to about three times its size before it becomes so, because it must first descend below the costal margin.
Its position behind the lower left ribs explains why fractures of ribs 9 to 11 on the left raise the possibility of splenic rupture, and why a delayed rupture can follow apparently minor trauma once a subcapsular haematoma expands.
The spleen is entirely intraperitoneal, covered in peritoneum except at the hilum.