Blood Supply to the Gut

Question 1

What are the three divisions of the gut and which main arteries are they supplied by (and at which spinal level)?

Answer 1

Foregut = coeliac trunk (T12)
Midgut = Superior mesenteric artery (L1)
Hindgut = Inferior mesenteric artery (L3)

Question 2

What spinal level does the coeliac trunk arise from and what does it trifurcate into?

Answer 2

• The coeliac trunk arises from the abdominal aorta at the level T12. It immediately trifurcates into:
  o Left gastric artery
  o Splenic artery
  o Common hepatic artery

Question 3

Which arteries supply the stomach?

Answer 3

See diagram in notes for locations
Oesophageal branches 
Left gastric artery
Short gastric branches
Left gastroepipolic artery
Right gastroepipolic artery
Superior prancreaticoduodenal artery
Gastroduodenal artery
Right gastric artery

Question 4

What are the components of the common hepatic artery?

Answer 4

Right hepatic artery
Left hepatic artery
Common hepatic artery
Right gastric artery
Gastroduodenal artery
Hepatic artery proper
Cystic artery

Question 5

What does the superior mesenteric artery branch into?

Answer 5

Middle colic artery
Inferior pancreaticoduodenal artery
SMA
Right colic artery
Jejunal and ileal branches
Ileocolic artery
Appendicular artery

Question 6

What are the differences between the jejunum and ileum?

Answer 6

Jejunum:

• Longer vasa recta
• Fewer arcades
• More vascular
• Less fat in mesentery
• Larger lumen

Ileum:

• Shorter vasa recta
• More arcades
• More fat in mesentery
• Smaller lumen
• Peyer’s patches

Question 7

What does the inferior mesenteric artery branch into?

Answer 7

• Left colic artery
• Sigmoidal artery
• Superior rectal artery

Question 8

What are the components of the rectal blood supply?

Answer 8

Superior rectal artery (IMA)
Middle rectal artery (internal iliac artery)
Inferior rectal artery (pudendal artery)

Question 9

What are the contributors to the hepatic portal vein?

Answer 9

Superior mesenteric vein
Inferior mesenteric vein
Splenic vein

Question 10

What are the veins serving the gut?

Answer 10

See diagram in notes

Question 11

How is the nervous system organised?

Answer 11

Somatic (sensory and motor to somites: musculoskeletal system, and skin)
Visceral (sensory and motor to viscera (organs) - parasympathetic and sympathetic)

Question 12

What spinal levels are the sympathetic nerves at? What do they initiate?

Answer 12

Sympathetic Nerves (T1-L2)
-	Fight or flight response:
o	Pupil dilation 
o	Cardiac acceleration
o	Inhibition of digestion
o	Piloerection
o	Vasoconstriction
o	Urinary filling
o	Sweating
o	Ejaculation

Question 13

What spinal levels are the parasympathetic nerves at? What do they initiate?

Answer 13

Parasympathetic nerves (CN III, VII, IX, X and spinal nerves S2-4) 
-	Rest and digest response:
o	Pupillary constriction 
o	Salivation/Lacrimation 
o	Cardiac deceleration
o	Stimulates digestion
o	Colon motility
o	Urination/defication
o	Erection

Question 14

What are the two types of outflow in the autonomic nervous system?

Answer 14

Parasympathetic = craniosacral outflow
Sympathetic = thoracolumbar outflow

Question 15

Which arteries, veins, nerves and ganglion supply the foregut?

Answer 15

Arterial supply: Coeliac trunk
Venous drainage: Splenic vein
Sympathetic nerve: Greater splanchnic nerve
Sympathetic ganglion: Coeliac ganglion
Parasympathetic nerve: Vagus X

Question 16

Which arteries, veins, nerves and ganglion supply the midgut?

Answer 16

Arterial supply: Superior mesenteric artery
Venous drainage: Superior mesenteric vein
Sympathetic nerve: Lesser and least splanchnic nerve
Sympathetic ganglion: Superior mesenteric ganglion
Parasympathetic nerve: Vagus X

Question 17

Which arteries, veins, nerves and ganglion supply the hindgut?

Answer 17

Arterial supply: Inferior mesenteric artery
Venous drainage: Inferior mesenteric vein
Sympathetic nerve: Lumbar splanchnic nerve
Sympathetic ganglion: Inferior mesenteric ganglion
Parasympathetic nerve: Sacral outflow (S2-4 - aka pelvic splanchnic nerves)