T2 L9: The liver

• How is the venous drainage of the gut like?

  according to direction of blood:

  1. Hindgut: inferior mesenteric vein
  2. Midgut: Superior mesenteric vein
  3. Foregut: (A) Splenic vein to Hepatic portal vein or straight into (B) HPV

  Hepatic veins from liver drain directly into inferior vena cava

  
• How is the blood supply to rectum and anal canal like?

  • inferior mesenteric artery -> (1) Superior rectal artery -> Rectum and anal canal superior to pectinate line
  • internal iliac artery -> (2) Middle rectal artery -> Anastomoses with superior and inferior rectal arteries
  • internal iliac artery -> internal pudendal artery -> (3) Inferior rectal artery -> Anal canal below pectinate line

  
• How is the lymphatic drainage of GI tract like?

  • Foregut: Celiac nodes ( -> ) Intestinal trunk
  • Midgut: Superior mesenteric nodes ( -> ) Intestinal trunk
  • Hindgut: Inferior mesenteric nodes ( -> ) lumbar trunks
  • inferior rectum and anal canal above pectinate line: Common iliac nodes ( -> ) lumbar trunks
  • anal canal below pectinate line: Superficial inguinal nodes ( -> ) lumbar trunks
• What is Cisterna chyli?

  Dilated lymphatic sac at the base of the thoracic duct.

  Drains lymph from the 3 lymphatic trunks in the GI tract:

  1. Right lumbar trunk
  2. Intestinal trunk
  3. Left lumbar trunk

  -> cisterna chyli -> thoracic duct
• How is the sympathetic innervation of the GI system?

  Foregut: Greater (thoracic) splanchnic nerve

  Midgut: Lesser (thoracic) splanchnic nerve

  Kidneys: Least (thoracic) splanchnic nerve

  Hindgut: Lumbar splanchnic nerves
• How is the Parasympathetic innervation of the GI system?

  Foregut and midgut: Vagus nerve (CNX)

  Hindgut: Pelvic splanchnic nerves

  
• What are the characteristics of splanchnic nerves?

  sympathetic fibres that don't synapse
• What are the 3 sympathetic ganglia of the abdomen?

  1. Celiac ganglion - greater splanchnic nerve - foregut
  2. Superior mesenteric ganglion - lesser splanchnic nerve - midgut
  3. Inferior mesenteric ganglion - lumbar splanchnic nerve - hindgut

  
• What are the 3 parts of the prevertebral plexus?

  1. Coeliac plexus
  2. Aortic plexus
  3. Superior hypogastric plexus

  
• Blood / Lymph / Nerves of Foregut?

  Arteries: Celiac trunk

  Veins: Splenic / portal

  Lymphatics: Celiac nodes

  Sympathetic nerves: Greater splanchnic

  Parasympathetic nerves: Vagus nerve
• Blood / lymph / nerves of the midgut?

  Arteries: Superior mesenteric

  Veins: Superior mesenteric

  Lymph: Superior mesenteric nodes

  Sympathetic nerves: Lesser splanchnic nerves

  Parasympathetic nerves: Vagus nerve
• Blood / lymph / nerves of the hindgut?

  Arteries: inferior mesenteric

  Veins: inferior mesenteric

  Lymph: Inferior mesenteric nodes

  Sympathetic nerves: lumbar splanchnic

  Parasympathetic nerves: pelvic splanchnic
• Liver: Introduction

  2.5% Total body weight

  20% of O2 consumption

  Moves with diaphragm

  Protected by right ribs 7 – 11

  Location:

  1. right hypochondrium
  2. epigastrium
  3. left hypochondrium

  
• What are the lobes and surfaces of the liver?

  1. Right lobe (anatomical)
  2. Left lobe (anatomical)
  3. Caudate lobe (accessory - arising from right lobe)
  4. Quadrate lobe (accessory - arising from right lobe)

  
• What are the segments of the liver?

  8 segments

  Each with its own branch of:

  • hepatic artery
  • portal vein
  • common hepatic duct (portal triad)
  • hepatic vein

  
• What is a hepatic segmentectomy?

  resecting some segments of the liver

  it is possible as there is no overlap in blood supply to each segment, so can be resected if injured / affected by a tumour etc

  
• What is the liver connected to the diaphragm by?

  coronary ligament

  superior surface

  
• What divides the left and right lobes of the liver?

  Falciform ligament

  also connects liver to the anterior abdominal wall

  embryologically derived from ventral mesogastrium

  
• What is the Porta hepatis?

  Liver hilum (entrance / exit of portal triad in transverse fissure)

  Contents:

  • Hepatic ducts join to form common hepatic duct
  • Hepatic portal vein entering liver
  • Hepatic arteries (from proper hepatic artery) entering liver

  
• What are the different impressions of the liver?

  1. Gastric impression (by stomach)
  2. Oesophageal impression (by oesophagus)
  3. Duodenal impression (by duodenum)
  4. Colic impression (by colon - hepatic flexure)
  5. Renal impression (by kidneys)
  6. Suprarenal impression (by suprarenal glands)

  
• What are the ligaments of the liver?

  1. Falciform ligament
  2. Coronary ligament
  3. Triangular ligament

  
• What is the bare area of the liver?

  area of liver with no peritoneum

  encircled by coronary ligaments

  directly against the diaphragm

  
• What are the boundaries of the Lesser Sac?

  Superior: Liver

  Inferior: Transverse mesocolon

  Posterior: Pancreas, aorta, celiac trunk (retroperitoneal organs)

  Anterior: Lesser omentum

  
• What is the Epiploic foramen?

  opening in the hepatoduodenal ligament into lesser sac

  Boundaries:

  • Superior: liver
  • Inferior: 1st part of duodenum
  • Posterior: Inferior vena cava and right crus of diaphragm
  • Anterior: Portal triad (in free edge of lesser omentum)

  
• What is the Portal Triad?

  run in free edge of lesser omentum (hepatoduodenal ligament)

  contents:

  1. Common bile duct
  2. Proper hepatic artery
  3. Hepatic portal vein
  4. Lymphatic vessels
  5. Nerves from hepatic plexus

  
• What is Pringle's manoeuvre?

  haemostat used to clamp hepatoduodenal ligament to stop blood flow through proper hepatic artery and hepatic portal vein

  
• What are the recesses of the liver?

  Recess: potential space where peritoneal fluid or metastases can localise

  1. Subphrenic space: between liver and diaphragm
  2. Right Subhepatic space: between inferior surface of liver and kidney
  3. Hepatorenal recess / Pouch of Morrison: extension of subhepatic space between liver and kidney. Fluid often accumulates here when patient is supine.

  
• How is the prenatal circulation through the liver?

  oxygenated blood → (1) umbilical vein → liver. Can either:

  • go through (2) hepatic portal vein → hepatic lobules in liver
  • or (3) ductus venosus → (4) inferior vena cava

  
• What is the embryological remnant of the umbilical vein in postnatal circulation?

  Ligamentum teres

  
• What is the embryological remnant of the ductus venosus in postnatal circulation?

  Ligamentum venosum

  
• What are the remnants of the umbilical vein in the adult liver?

  Ligamentum teres (fissure for round ligament)

  extending from Falciform ligament

  
• What is the remnant of ductus venosus in the adult liver?

  Ligamentum venosum

  
• What was the function of ductus venosus?

  shunt umbilical blood directly into IVC
• What was the function of umbilical vein?

  carry oxygenated blood from placenta

  Small paraumbilical veins may remain in substance of ligament
• What is the dual blood supply of liver?

  1. Celiac trunk → Common hepatic artery → Proper hepatic artery → Left & right hepatic arteries (oxygen rich, 25%)
  2. Hepatic portal vein (nutrient rich, 75%), coming from:
  3. superior mesenteric artery
  4. inferior mesenteric artery
  5. splenic vein

  
• What happens at the hepatic sinusoids?

  mixing of blood coming from hepatic arteries and hepatic portal vein

  
• What is the route of blood supply and drainage in and through the liver?

  2 blood supplies:

  1. Proper hepatic artery (oxygen rich, 25%) → hepatic arteries
  2. Hepatic portal vein (nutrient rich, 75%)

  → hepatic sinusoids (mix) → central veins → hepatic veins → inferior vena cava

  
• What is the structure of the hepatic lobule?

  Hexagonal

  bile duct, branch of hepatic portal vein and branch of hepatic artery on edges

  sinusoids draining into central vein

  
• What are Portostystemic Anastamoses and what are 3 examples?

  collateral circulation between systemic and portal circulation

  1. Oesophagus
  2. Peri-umbilical region
  3. Anal canal

  
• How does the Portosytemic Anastomosis occur in the oesophagus region?

  Anastamosis of

  • Left gastric vein (portal - drains into hepatic portal vein)
  • Oesophageal vein (systemic - drains into azygos veins)

  In portal hypertension, causes: Oesophageal varices