13. Anatomy of Abdominal Visceral Vessels

I. Abdominal Visceral Arteries

• Abdominal aorta runs anterior to vertebral bodies from diaphragm to bifurcation
• Major unpaired visceral branches

1. Celiac trunk → T12 level → Foregut
2. Superior mesenteric artery (SMA) → L1 level → Midgut
3. Inferior mesenteric artery (IMA) → L3 level → Hindgut

1. Celiac Trunk

• First major unpaired branch of abdominal aorta
• Arises at T12 level, just below aortic hiatus
• Supplies foregut organs

• Lower esophagus
• Stomach
• Proximal duodenum to major papilla
• Liver, gallbladder, extrahepatic biliary tree
• Pancreas partly
• Spleen

Main Branches

1. Left gastric artery

• Smallest celiac branch
• Supplies lesser curvature of stomach and lower esophagus
• Anastomoses with right gastric artery

2. Splenic artery

• Tortuous course along superior border of pancreas
• Supplies spleen, pancreatic body/tail and stomach
• Branches

• Pancreatic branches → Pancreatic body and tail
• Short gastric arteries → Fundus of stomach
• Left gastroepiploic artery → Greater curvature of stomach
• Terminal splenic branches → Spleen

3. Common hepatic artery

• Runs toward hepatoduodenal ligament
• Branches

• Proper hepatic artery → Right and left hepatic arteries → Liver
• Right hepatic artery usually gives cystic artery → Gallbladder
• Right gastric artery → Lesser curvature; anastomoses with left gastric artery
• Gastroduodenal artery → Right gastroepiploic artery + superior pancreaticoduodenal arteries

2. Superior Mesenteric Artery (SMA)

• Arises from abdominal aorta at L1 level
• Passes posterior to neck of pancreas, anterior to third part of duodenum
• Supplies midgut organs

• Distal duodenum from major papilla
• Jejunum and ileum
• Cecum and appendix
• Ascending colon
• Proximal two-thirds of transverse colon

Main Branches

• Inferior pancreaticoduodenal artery → Head of pancreas + distal duodenum
• Jejunal and ileal arteries → Small bowel via arterial arcades and vasa recta
• Ileocolic artery → Terminal ileum, cecum, appendix, proximal ascending colon
• Right colic artery → Ascending colon; may be absent/variable
• Middle colic artery → Proximal two-thirds of transverse colon

3. Inferior Mesenteric Artery (IMA)

• Arises from abdominal aorta at L3 level
• Supplies hindgut organs

• Distal one-third of transverse colon
• Descending colon
• Sigmoid colon
• Upper rectum

Main Branches

• Left colic artery → Descending colon + distal transverse colon
• Sigmoid arteries → Sigmoid colon
• Superior rectal artery → Upper rectum

II. Abdominal Visceral Veins

Portal Venous System

• Portal system drains gastrointestinal tract, spleen, pancreas and gallbladder to liver
• Main formation → SMV + splenic vein → Portal vein
• Portal vein enters liver at porta hepatis inside hepatoduodenal ligament
• Portal triad in hepatoduodenal ligament

• Common bile duct → Right anterior
• Proper hepatic artery → Left anterior
• Portal vein → Posterior

1. Superior Mesenteric Vein (SMV)

• Drains midgut territory
• Tributaries

• Small intestine veins
• Ileocolic, right colic and middle colic veins
• Ascending colon and proximal two-thirds of transverse colon
• Pancreaticoduodenal veins from pancreatic head/duodenum
• Usually right gastroepiploic vein also drains to SMV

2. Inferior Mesenteric Vein (IMV)

• Drains hindgut territory
• Usually joins splenic vein; sometimes joins SMV or SMV-splenic confluence
• Tributaries

• Left colic vein → Distal transverse/descending colon
• Sigmoid veins → Sigmoid colon
• Superior rectal vein → Upper rectum

3. Splenic Vein

• Runs posterior to pancreas
• Joins SMV behind neck of pancreas → Portal vein
• Tributaries

• Splenic veins → Spleen
• Pancreatic veins → Pancreatic body and tail
• Short gastric veins → Fundus of stomach
• Left gastroepiploic vein → Greater curvature
• Usually IMV

4. Gastric Veins

• Left gastric vein → Portal vein; important in esophageal varices
• Right gastric vein → Portal vein
• Short gastric veins → Splenic vein
• Left gastroepiploic vein → Splenic vein
• Right gastroepiploic vein → SMV

Systemic Venous System

• Middle and inferior rectal veins → Internal iliac veins → Common iliac veins → IVC
• Esophageal veins → Azygos system → SVC
• Retroperitoneal veins/body wall veins → Caval system

III. Important Anastomoses and Collateral Circulation

Arterial Anastomoses

• Pancreaticoduodenal arcades → Celiac trunk ↔ SMA

• Superior pancreaticoduodenal arteries from gastroduodenal artery
• Inferior pancreaticoduodenal artery from SMA
• Important collateral route in celiac/SMA stenosis

• Marginal artery of Drummond → Continuous arcade along mesenteric border of colon

• Connects ileocolic/right colic/middle colic/left colic/sigmoid branches
• SMA ↔ IMA collateral
• Important during colectomy and vascular ligation

• Arc of Riolan / meandering mesenteric artery → Inconstant central collateral

• Connects middle colic artery (SMA) ↔ left colic artery (IMA)
• May enlarge in chronic mesenteric arterial stenosis

• Rectal arterial anastomoses

• Superior rectal artery → IMA
• Middle/inferior rectal arteries → Internal iliac system
• Important in rectal surgery and pelvic collateral flow

Portosystemic Anastomoses

IV. Lymphatic Drainage and Surgical Relevance

Lymphatic Drainage

• Abdominal visceral lymphatics usually follow arterial supply
• Foregut lymph → Celiac nodes
• Midgut lymph → Superior mesenteric nodes
• Hindgut lymph → Inferior mesenteric nodes
• Nodes → Intestinal lymph trunks → Cisterna chyli → Thoracic duct

Surgical Relevance

• Knowledge of vessels defines safe ligation planes in gastrectomy, pancreatectomy, colectomy and liver surgery
• Oncological surgery follows vascular lymph drainage → Lymphadenectomy around named vessels
• Colon cancer resection → Ligate segmental artery with lymph nodes along vascular pedicle
• Watershed areas are ischemia-prone

• Splenic flexure / Griffith point → SMA-IMA border
• Rectosigmoid / Sudeck point → IMA-superior rectal collateral border

• Portal hypertension surgery/endoscopy must consider varices and portosystemic collaterals
• Splenic vein thrombosis can cause left-sided portal hypertension → Gastric varices
• Mesenteric ischemia often involves SMA territory → Severe pain, bowel necrosis risk
• Hepatoduodenal ligament anatomy is critical for Pringle maneuver

• Pringle maneuver compresses portal triad → Temporary control of hepatic inflow bleeding