Solid organ lying in the left upper quadrant.
It is not a part of the alimentary tract, but drains to the portal system.
Imperial rule of 1,3,5,7,9,11: (averages, does vary considerably)
- size 1x3x5in (11cm in longest axis; 22cm = massive splenomegaly)
weight 7oz (150g)
- lies between 9th & 11th ribs (along axis of 10th rib)
Lies in the LUQ, in peritoneum of original
left leaf of dorsal mesogastrium; splits this into its two
Lies posteriorly with convexity against diaphragm, concavity related to stomach, tail of pancreas, L kidney.
- lower pole doesnŐt extend beyond midaxillary line in health; not usually palpable.
below its lower pole phrenocolic
ligament attaches splenic flexure to diaphragm
- pushes splenic flexure ahead when enlarging, hence dull to percussion unlike a kidney mass which has air over it.
All of its surfaces are invested in visceral peritoneum; leaves of greater omentum pass from its hilum to greater curve of stomach as the gastrosplenic ligament
- this is
very short, often only 1cm; careful control of stomach GC
necessary when mobilising this or can be damaged.
- and backwards to the front of the left kidney as the lienorenal ligament.
These are usually bloodless, except in portal hypertension.
pushes colon ahead \ colon never overlies it (thus percussion over spleen always dull cf kidney). ¨ follows line of 10th rib to direction of umbilicus as it grows.
- must at least double in size before its anterior border becomes palpable; has a notch.
gastric: lies between hilum and notched anterior border;
concave renal: lies behind hilum;
5% of CO
artery: runs along upper border
of pancreas, gives off dorsal pancreatic artery and 2-10
unnamed branches to pancreas and great pancreatic a.
- In 2/3, a branch arises from midpoint running up behind peritoneum to post. aspect of stomach, = posterior gastric artery.
Terminates as smaller branches to spleen, left gastroepiploic and short gastrics (x3-4); passes through the lienorenal ligament at the hilum; gives 2-3 branches, which form >5 more then enters spleen.
- hence spleen has segmental supply; upper & lower polar segments, and 1-5 central segments
- artery dividing near spleen = magistral pattern (30%), earlier division = distributing splenic pattern (70%) (important in splenic conservation)
Splenic vein: confluence of 2-6 tributaries in splenorenal ligament. Receives L gastroepiploic vein; upper/lower polar branches may drain well beyond hilum. (290)
- is valveless
- meets superior mesenteric behind the neck of the pancreas portal vein.
Lymph: nodes at hilum --> pancreaticosplenic nodes --> coeliac nodes (299)
Nerves: coeliac plexus (sympathetic only)
Begins in 6th week as mesodermal condensation in the dorsal mesogastrium & divides that structure into lienorenal and gastrosplenic ligaments.
Comes to lie at L margin of lesser sac
intra-abdominally; unlike the pancreas (which also develops in
the dorsal mesogastrium)
Spleen forms from fusion of foetal splenules.
- the splenic notch is due to incomplete fusion
- splenunculus (accessory spleens) due to failure of fusion (20% population, rarely larger than 2cm).
- these lie along the course of development: splenic artery, hilum, lienorenal and gastrosplenic ligaments, but also mesentery, in pelvis (female gonads), testicles; though most found close to spleen.
1. Search for and remove accessory spleens in above locatios during splenectomy for haematologic reasons.
- found in 10-30%; typically only 1; can be
multiple; us <3cm
- apart from above, also reported in liver
2. Magistral pattern recognition important in splenic conservation.
3. For elective splenectomy, open gastrocolic
omentum, isolate splenic artery and dissect with care, quit
- then splenic vein laterally.
- in massive splenomegaly, ned to eembolizing aretry first
- in lap, either dissect hilar first then
mobilize; or didvide posteriro leaf first; dpends on surgeon