Blood supply to the gut CAM
Learning Objectives
Understand anatomy and distribution of the 3 unpaired arteries of the abdominal aorta.
Describe blood supply to the liver and formation of the hepatic portal vein.
Review autonomic nerve supply to the gut.
Blood Supply and Drainage
Overview of Blood Supply to the Gut
The gastrointestinal system is supplied by 3 unpaired arteries:
Foregut: Coeliac trunk
Midgut: Superior mesenteric artery (SMA)
Hindgut: Inferior mesenteric artery (IMA)
Other abdominal arteries include:
Renal arteries
Gonadal arteries
Lumbar arteries
Divisions of the Gut Tube
Foregut
Supplied by the coeliac trunk (T12).
Midgut
Supplied by the superior mesenteric artery (L1).
Hindgut
Supplied by the inferior mesenteric artery (L3).
Abdominal Aorta and Arteries
Coeliac trunk: T12
Superior mesenteric artery (SMA): L1
Inferior mesenteric artery (IMA): L3
Aortic bifurcation into common iliac arteries occurs at L4.
Detailed Blood Supply Contributions
Coeliac Trunk:
Branches include:
Splenic artery
Left gastric artery
Common hepatic artery
Supplies the foregut (e.g., abdominal esophagus, stomach, liver, gallbladder, pancreas, proximal duodenum).
Blood Supply to the Stomach
Blood supply derived from:
Gastric arteries in the lesser omentum
Gastroepiploic arteries in the greater omentum
Includes:
Left gastroepiploic artery
Right gastroepiploic artery
Right gastric artery
Short gastric arteries
Extensive anastomoses between these circuits, particularly from the pancreatoduodenal region.
Common Hepatic Artery Components
Contains:
Hepatic artery proper
Gastroduodenal artery
Cystic artery and branches to left and right hepatic arteries
Right gastric artery.
Blood Supply to Spleen and Pancreas
Supplied by:
Common hepatic artery
Hepatic artery proper
Gastroduodenal artery
Pancreatoduodenal artery branches.
Anastomoses between coeliac trunk and SMA via pancreatoduodenal arteries.
Midgut Blood Supply - Superior Mesenteric Artery (SMA)
Supplies:
Jejunum and ileum via jejunal and ileal arteries
Ascending and transverse colon via ileocolic and right/middle colic arteries.
Arises from L1 between mesentery layers.
Branches of Superior Mesenteric Artery (SMA)
Includes:
Jejunal and ileal branches
Ileocolic artery (supplies appendix)
Right colic artery
Middle colic artery
Inferior pancreaticoduodenal artery.
Anastomoses between Coeliac and SMA
Key connections include:
Anterior and posterior superior pancreaticoduodenal arteries.
Comparison of Jejunum and Ileum
Jejunum:
Longer vasa recta, fewer arcades, less fat, larger lumen, more vascular.
More prominent Peyer’s patches.
Ileum:
Shorter vasa recta, more arcades, more fat, smaller lumen, less vascular.
Blood Supply to the Colon - SMA
Includes:
Marginal artery
Middle colic
Right colic
Ileocolic
Appendicular.
Blood Supply to the Descending Colon - IMA
Comprised of:
Marginal artery
Left colic
Sigmoid arteries
Superior rectal artery.
Rectal Blood Supply
Supplied by:
Superior rectal artery (from IMA)
Middle rectal artery (from internal iliac artery)
Inferior rectal artery (from pudendal artery).
Vulnerability during Ischemia
During artery blockage (e.g., atherosclerosis), watershed areas are spared due to dual supply. Systemic hypoperfusion (e.g., DIC or heart failure) increases risk of ischemia due to reliance on distal branches.
Hepatic Portal System of Veins
75% of blood flow to the liver is via portal vein (25% from hepatic artery).
Formed by:
Splenic vein
Superior mesenteric vein (SMV) which meets retroperitoneally behind pancreas.
Inferior mesenteric vein (IMV).
Involves 4 important sites of porto-systemic anastomoses.
Formation of the Hepatic Portal Vein
Comprised of:
Splenic vein
Superior mesenteric vein
Inferior mesenteric vein
Left gastric vein.
Autonomic Nervous System in Gut Control
Parasympathetic Division
Associated with rest and digest functions.
Vagus nerve (CN X) and pelvic splanchnic nerves (S2-4).
Effects:
Increased motility and peristalsis
Increased secretion of digestive enzymes
Relaxation of sphincters
Stimulation of enteric nervous system.
Sympathetic System
Postganglionic fibers from:
Coeliac ganglion
Superior mesenteric ganglion
Inferior mesenteric ganglion.
General effects include:
Dilated pupils
Inhibited salivation, peristalsis, and secretion
Increased heart rate and glucose production.
Lymphatic Drainage of the Gut
Follows arterial supply, ultimately draining to cisterna chyli and thoracic duct.
Lymphatic Drainage of Foregut
Drains via local lymph nodes:
Gastric, hepatic, pancreatosplenic, pancreatoduodenal, pyloric lymph nodes.
These drain into coeliac lymph nodes (around the coeliac trunk) and into the thoracic duct.
Lymphatic Drainage of Midgut
Primarily via superior mesenteric lymph nodes:
Includes mesenteric, ileocolic, right colic, and middle colic, ultimately draining to thoracic duct.
Lymphatic Drainage of Hindgut
Involves inferior mesenteric lymph nodes related to the IMA:
Local nodes include left colic, sigmoid, and superior rectal lymph nodes.
Drains into superior mesenteric or directly into cisterna chyli.
Lymphatics and Metastatic Pathways
Cancer Spread Pathways
Gastric Cancer:
Spreads via celiac nodes to thoracic duct.
Involved in Virchow’s node (left supraclavicular node) which indicates abdominal malignancy.
Colon Cancer:
Right-sided (ascending colon) drains to superior mesenteric nodes.
Left-sided (descending/sigmoid colon) drains to inferior mesenteric nodes.
Rectal Cancer:
Above pectinate line drains to inferior mesenteric and internal iliac nodes; may metastasize to para-aortic nodes.
Below the pectinate line drains to superficial inguinal nodes, which can be palpated.
Additional Overview
Unpaired abdominal arteries:
Coeliac trunk, superior mesenteric artery, inferior mesenteric artery.
Unpaired veins draining to portal vein:
Splenic vein, superior mesenteric vein, inferior mesenteric vein.
Sympathetic and parasympathetic nerve connections throughout the gut, involved in gut function and regulation.
Lymphatic drainage organized by specific regions corresponding to arterial supply (coeliac, superior mesenteric, inferior mesenteric lymph nodes).