Vasculature, innervation and lymphatics of the GI tract Flashcards
What organs does the coeliac trunk supply
Oesophagus Spleen Stomach Liver Gall bladder Pancreas 1st and 2nd part of duodenum
What does the superior mesenteric artery supply
3rd and 4th part of the duodenum Jejunum Ileum Appendix Ascending colon Caecum Proximal 2/3 of transverse colon
What does the inferior mesenteric artery supply
Distal 1/3 of transverse colon Descending colon Sigmoid colon Rectum Upper anal canal Urogenital Sinus
3 main branches of coeliac trunk
left gastric
splenic
common hepatic
Where does the coeliac trunk arise from?
Anterior surface of abdominal aorta at the vertebral level of T12
Where is the left gastric artery found and what branches does it give off
Upper part of the lesser curvature of stomach
Oesophageal branches
Where does the splenic artery travel to and what branches does it give off
Travels left towards the spleen along the superior border of the pancreas
Tortuous course
Gives branches to neck, body and tail of pancreas
Gives off short gastric branches and left gastroepiploic
What does the splenic artery and branches supply
Spleen
Neck, body and tail of pancreas
Short gastric branches - fundus of stomach
Left gastroepiploic - upper part of greater curvature of the stomach
What are the two terminal branches of the common hepatic artery
Hepatic artery proper
Gastroduodenal artery
What is the course of the hepatic artery proper and what does it supply
Ascends towards liver in the free edge of the lesser omentum, divides into right and left hepatic arteries
Right hepatic artery supplies the gallbladder by the cystic artery
What branches does the gastroduodenal artery give and what do they supply
Gives right gastroepiploic artery - lower part of greater curvature
Superior pancreaticoduodenal artery - splits into anterior and posterior branches that supply head of pancreas and duodenum
What does the right gastroepiploic artery anastomose with
L gastroepiploic artery
What does the right gastric artery anastomose with
Left gastric artery
Where is the superior mesenteric artery found
Arises from the anterior surface of the abdominal aorta at vertebral level L1
Lies behind the neck of the pancreas
Crosses anteriorly over the 3rd part of the duodenum
What is the inferior pancreaticoduodenal artery
First branch of superior mesenteric artery
Splits into anterior and posterior branches
Supplies duodenum and head and uncinate process
Branches of superior mesenteric on the left
numerous jejunal and ileal arteries supplying the jejunum and most of the ileum
3 branches of right side of superior mesenteric artery
Middle colic artery
Right colic artery
Ileocolic artery
Where does the middle colic artery supply and what are it’s branches
Enters transverse mesocolon
Supplies proximal 2/3 of transverse colon
Left and right branch
Left branch anastomoses with left colic and right branch anastomoses with right colic
Where does the right colic supply and what are its two branches
Supplies ascending colon
Ascending branch and descending branch
Where is the ileocolic artery found and what are it’s branches and theie supplies
Passes into right iliac fossa
Superior branch - ascending colon
Inferior branch towards ileocolic junction
What arteries are found in the inferior branch of the ileocolic artery
Colic branches
Caecal arteries
Appendicular artery
Ileal branch
Where is the inferior mesenteric artery found
Arises from the anterior surface of the abdominal aorta at vertebral level of L3
About 1.5 inches above the bifurcation of the aorta
Passes downwards and to the left, crossing the left common iliac artery
Branches of the inferior mesenteric artery
Left colic artery
Several sigmoid arteries
Superior rectal artery
What does the left colic artery supply
Ascending branch - supplies distal 1/3 of transverse colon and upper part of Descending colon
Descending branch- Lower part of descending colon
What is the superior rectal artery
Terminal branch of inferior mesenteric artery
Descends into pelvic cavity to supply the rectum to the level of the internal anal sphincter
Anastomosis with middle rectal artery and inferior rectal artery
What 3 arteries supply the rectum
Superior rectal artery - from inferior mesenteric artery
Middle rectal artery - branch of the internal iliac artery
Inferior rectal artery - branch of the internal pudendal artery
Anastomose together
What is the marginal artery
Single arterial trunk that connects superior mesenteric and inferior mesenteric arteries
Runs along inner border of the colon
Formed by anastomosing branches of the ileocolic, right colic, middle colic, left colic and sigmoid arteries
What are the two venous systems of the abdomen
Portal venous system - venous blood passes through the liver for processing
Systemic venous system - venous blood that joins the inferior vena cava without going to the liver
How is the IVC formed
Union of common iliac veins at L5
How is the protal vein formed
Union of splenic vein and superior mesenteric vein
Behind neck of pancreas
L2
Course of the portal vein
Enters the liver and breaks up into sinusoids and then hepatic veins that drain into the IVC
What is present between lobules of the liver
Portal triads - branch of hepatic artery, branch of portal vein and a bile duct tributary
How does blood supply and drainage occur in liver lobule
Arterial and portal venous blood passes into sinusoids between liver cells
Bile passes travels in the opposite direction, towards the bile duct to exit the liver
What does the superior mesenteric vein drain?
Small intestine (jejunal and ileal veins)
Caecum (ileocolic v.)
Ascending colon (right colic v.)
proximal part of transverse colon (middle colic v.)
Also receives right gastroepiploic v., inferior pancreaticoduodenal v.
Pathway of superior mesenteric vein
Begins in right iliac fossa, ascends in the mesentery of small intestine
Joins the splenic vein behind the neck of pancreas
What does the inferior mesenteric vein drain
Rectum (rectal veins)
Sigmoid colon (sigmoid veins)
Descending colon (left colic vein)
Distal transverse colon (left colic vein)
Pathway of inferior mesenteric vein
Begins as the superior rectal vein
Receives sigmoid vein and left colic vein
It ascends behind the body of he pancreas and joins the splenic vein
Tributaries of the portal vein
Right and left gastric vein Cystic veins Paraumbilical veins Superior mesenteric vein Splenic vein
What are the tributaries of splenic vein and what does it drain
Short gastric vein, left gastroepiploic vein from greater curvature, pancreatic veins and inferior mesenteric veins
Drains the spleen
Communications between portal ns systemic venous systems
Oesophageal - gastroesophageal junction
Rectal - superior rectal vein anastomoses with the middle and inferior veins
Paraumbilical - paraumbilical veins anastomose with veins draining the anterior abdominal wall
What are the 3 preaortic lymph nodes that drain the abdomen and what do they drain into
Coeliac group, superior mesenteric group and inferior mesenteric group
Eventually drain into cisterna chyli -> thoracic duct
Key difference between sympathetic pathway and parasympathetic pathway
Sympathetic - short preganglionic neuron, log post ganglionic neuron
Parasympathetic - long preganglionic and short post ganglionic
Pathway of sympathetic division of GI tract
Originate from thoracic and lumbar region
Pre-ganglionic fibres leave spinal cord and synapse in sympathetic chain ganglia or travel through sympathetic chain without synapsing
Long postganglionic fibres then travel to target tissue
Pathway of parasympathetic division of GI tract neurons
Originate in the brainstem in the cranial nerves or from the sacral region for controlling pelvic region
Vagus nerve innervates abdominal viscera
Pelvic nerves innervate pelvic viscera
Long preganglionic fibres
Ganglia are usually near or on target tissue
Short post-ganglionic fibres
Sympathetic splanchnic nerves in the abdomen
Greater splanchnic - coeliac
Lesser splanchnic - aorticorenal, sometimes coeliac, superior mesenteric
Least splanchnic - aorticorenal
Lumbar splanchnic - inferior mesenteric ganglion
4 main sympathetic ganglia
Coeliac
Aorticorenal
Superior mesenteric
Inferior mesenteric
What parts of the GI tract does the vagus nerve supply
Supplies oesophagus to proximal part of colon (foregut, midgut) and other organs derived from the foregut and midgut
Parasympathetic splanchnic nerves
Pelvic splanchnic (S2-S4)
Supplies hindgut
