Blood Supply Of The GI Tract Flashcards
Where does the abdominal aorta lie
Lies just to the left of the midline on the posterior abdominal wall
Right and left common iliac arteries
Branches of the abdominal aorta
Supply the pelvis and lower limbs
At what level does the aorta bifurcate
L4/5
3 unpaired branches of the anterior aspect of the abdominal aorta
Coeliac trunk
Superior mesenteric artery
Inferior mesenteric artery
At what level does the coeliac trunk branch from the aorta
T12
At what level does the superior mesenteric artery branch from the aorta
L1
At what level does the inferior mesenteric artery branch from the aorta
L3
What does the coeliac trunk supply
Foregut: oesophagus, stomach, first 1/2 of duodenum, liver, gallbladder, pancreas, spleen
What does the superior mesenteric artery supply
Midgut: second 1/2 of duodenum, Jejunum, ileum, caecum, appendix, ascending colon, proximal 2/3 transverse colon
What does the inferior mesenteric artery supply
Hindgut: distal 1/3 transverse colon, descending colon, sigmoid colon, rectum
3 branches of coeliac trunk
Left gastric artery
Splenic artery
Common hepatic artery
Left gastric artery supplies…
Stomach
Splenic artery supplies…
Spleen
Stomach
Pancreas- branches come off as travels to spleen
Common hepatic artery supplies…
Liver
Gallbladder
Stomach
Duodenum
Branches of superior mesenteric artery (SMA)
Jejunal and ileal branches
Ileocolic artery
Right colic artery
Middle colic artery
Jejunal and ileal branches supply…
Jejunum and ileum
Ileocolic artery supplies…
Ileum
Caecum
Appendix
Ascending colon
Right colic artery supplies…
Ascending colon
At what level is the aortic hiatus in the diaphragm
T12
Middle colic artery supplies…
Transverse colon
Branches of inferior mesenteric artery (IMA)
Left colic artery
Sigmoid branches
Superior rectal artery
Left colic artery supplies…
Descending colon
Sigmoid branches supplies…
Sigmoid colon
Superior rectal artery supplies…
Rectum
Mesenteric ischaemia
thrombus in a mesenteric artery (or one of its branches) leading to hypoperfusion of the segment of gut the vessel supplies. Can progress to infarction of the gut. Mortality is high.
Ulcers of the stomach and duodenum
may erode through nearly vessels and cause severe intra-abdominal bleeding.
Abdominal aortic aneurysm
part of the wall of the aorta weakens and bulges / expands. Rupture has a high mortality – older people, sudden onset severe abdominal / back pain, rapid bleeding, circulatory shock.
Systemic veins
Carry venous blood directly to inferior vena cava
Blood does NOT pass through liver
Examples of systemic veins in abdomen
Renal veins
Adrenal veins
Hepatic veins
Examples of paired branches of abdominal aorta
Renal arteries
Gonadal arteries
Lumbar arteries
Unpaired branches of abdominal aorta
Celiac trunk
Superior mesenteric
Inferior mesenteric
Left gastro-omental artery
Branch of splenic artery
Supplies left border of stomach and part of omentum
When does the common hepatic artery —-> hepatic artery proper
When gastroduodenal artery branches off
What does the hepatic artery proper branch into
Right and left hepatic arteries
What does the right gastro-omental arise from
Gastroduodenal from common hepatic artery
What does the left gastro-omental arise from
Splenic artery
Which arteries supply to greater curvature of the stomach
Right and left gastro-omental arteries
Anastomose
Which arteries supply the lesser curvature of the stomach
Left and right gastric arteries
Anastomose
Portal veins
carry nutrient-rich venous blood from the gut to the liver
Blood then enters the hepatic veins and returns to the inferior vena cava
Examples of portal veins
Superior and inferior mesenteric veins
Portal system
Inferior mesenteric vein unites with splenic vein
Splenic vein unites with superior mesenteric vein to form hepatic portal vein
Hepatic portal vein enters liver
Blood is processed, nutrients removed, and the venous blood then enters the hepatic veins, which join the inferior vena cava.
Why don’t anastomosed vessels burst
Smaller branching arteries supply the surrounding viscera
So blood is constantly removed
Marginal artery
Anastomose of left colic and middle colic
Liver metastases
from colon cancer – cancers of the colon often metastasize to the liver because venous blood from the colon is carried first to the liver via the portal system.
Portal hypertension
high blood pressure in the portal system because of obstruction to flow through the portal vein or liver. Can lead to distended veins and bleeding at sites of portosystemic anastomoses.
Order of portal system
Inferior mesenteric vein + splenic vein ——> + superior mesenteric vein ——> Hepatic portal vein ——> liver ——>hepatic veins (systemic) ——> inferior vena cava
Venous drainage of distal oesophagus
BOTH
Azygos —> superior vena cava
AND
Gastric veins —> portal veins —> liver —> inferior vena cava
Branches of coeliac trunk clockwise
Left gastric
Splenic
Common hepatic
Branches of superior mesenteric artery clockwise
Jejunal and ileal branches
Ileocolic
Right colic
Middle colic
Branches of inferior mesenteric artery clockwise
Left colic
Sigmoid
Superior rectal
Name of anastomoses of left and middle colic arteries
Marginal artery
Left portal vein supplies
Quadrate, caudate and left lobes of liver
Right portal vein
Receives the cystic vein
Supplies right lobe of liver
At what level does the portal vein form
L2
Where is the Meissner’s plexus located
Submucosa of small intestine