Liver Anatomy Flashcards
What are the surfaces of the liver?
- diaphragmatic
- visceral
- bare area
- recesses
What is the subphrenic recess?
Separates the liver from the diaphragm
Divided longitudinally by falciform ligament
What is the hepatorenal recess?
Separates the liver from the right kidney
Where do the subphrenic and hepatorenal recesses meet?
Anteriorly
What are the lobes of the liver?
4 lobes: large right (includes 2 accessory lobes) and left
What are the properties of the liver lobes?
Attached to the anterior wall by the peritoneum via the falciform ligament
What is the falciform ligament?
Divides subphrenic recess into 2 regions
Continues as ligamentum teres
What are the ligaments of the liver?
Falciform ligament
Coronary ligament
Triangular ligament
(all formed from peritoneum)
Posteriorly what are the right and left liver lobes separated into?
- caudate lobe: between fissure for ligamentum venosum and groove for IVC (next to IVC as begins with C), superior
- quadrate lobe: between fissure for ligamentum teres and gall bladder, inferior
- bare area: no periteoneum between A/P coronary ligaments, gallbladder fossa and porta hepatis
What does the lesser omentum connect to the liver?
Hepatoduodenal and hepatogastric ligaments
Lesser omentum is divided into the hepatoduodenal and hepatogastric ligaments
What is the porta hepatis?
- gateway to the liver
- made up of hepatic portal vein, hepatic artery and bile duct
What are the Couinaud segments?
Hepatic artery and portal vein subdivide lobes into eight segments
Divided vertically by hepatic veins and horizontally by left and right portal veins
Each segment has its own vessels (portal triad + hepatic vein)
What is the role of the hepatic vein?
Flow through liver returns through here to IVC
What carries blood into liver lobule sinusoids?
Branches of hepatic artery and portal vein
What forms the portal vein and where?
Splenic and superior mesenteric veins meet posterior to head of pancreas
Where does the inferior mesenteric vein drain?
To splenic vein
What are the portosystemic anastomoses?
Anastomoses between veins of portal circulation and systemic circulation, provides alternative circulatory routes when there is a blockage in liver/portal vein
What is cirrhosis?
consequences of chronic liver disease
replacement of liver tissue by fibrosis, scar tissue and regenerative nodules (due to damage) leading to loss of liver function
What is portal hypertension?
When portal pressure gradient is greater than 5mmHg
What is the portal pressure gradient?
Pressure between portal vein and IVC
What are oesophageal varices?
- occur at anastomoses of left gastric vein with oesophageal veins as gastro-oesophageal junction
- present with haematemesis (vomiting blood)
- treated with oesophageal banding (tie around to cut off blood supply so falls off)
- portal hypertension so blood cannot get through liver and backtracks up oesophagus to systemic system which is not built for overload so vessels twist
What are some causes of oesophageal varices?
- peptic/gastroduodenal ulcers
- tumors
- erosion of oesophagus
- gastroenteritis
What is ascites?
- fluid in peritoneal space
- due to: portal hypertension, hypoalbuminemia, aldosterone related renal sodium retention with consequent blood volume expansion
What is caput medusae?
- recanalized umbilical vein within falciform ligament
- paraumbilical veins radiate superiorly to intercostal veins and inferiorly to inferior epigastric vein
How can you tell the difference between haemorrhoids and ano-rectal varices?
Rectal varices are not haemorrhoids
rectal varices - due to portal hypertension as formation of portosystemic shunts, bleed massively
Varices always due to portal hypertension but haemorrhoids not always
Which veins are portal and which are systemic?
Systemic - internal iliac vein, middle rectal vein, inferior rectal vein
Portal - inferior mesenteric vein, superior rectal vein
What drains the oesophagus?
Portal - left gastric vein
Systemic - azygos and hemiazygos
- oesophageal varices, haematemesis
What drains the rectum?
Portal - superior rectal vein
Systemic - inferior rectal vein
- recto-anal varices
What drains the anterior abdominal wall?
Portal - paraumbilical veins
Systemic - intercostal and inferior epigastric veins
- caput medusae
What drains the retro-peritonel organs?
Portal - duodenal, pancreatic, right/left colic veins
Systemic - lumbar veins
- retroperitoneal haemorrhage
What are the parts of the biliary tree?
Cystic duct neck body L+R hepatic ducts common hepatic ducts bile duct (lies in groove on posterior surface of pancreas) Hepatopancreatic ampulla of Vater fundus major duodenal papilla surrounded by sphincter of Oddi
How is bile secreted?
- by liver at a constant rate of 40ml/hour
- canaliculi drain into interlobar ducts
- bile ducts form left and right hepatic ducts at porta hepatis
- right hepatic duct -> right lobe and left hepatic duct -> left lobe, caudate and quadrate lobe
- bile ducts leave the porta hepatis -> form common hepatic duct
What is the significance of the gall bladder?
concentrates bile
related to hepatic flexure of colon and duodenum
inflamed gall bladder (cholecystitis) herniates into colon and duodenum
pain in right upper quadrant (right flank and right scapula)
What is the blood supply to the gallbladder?
From common hepatic artery -> right hepatic artery -> cystic artery
In what abdominal quadrant is the liver in?
Right hypochondrium
What is the pringle manoeuvre?
Clamp hepatoduodenal ligament to interrupt flow of blood through hepatic artery and portal vein controlling bleeding from the liver and allowing you to identify the source of bleeding
What is the free border of the lesser omentum?
Hepatoduodenal ligament
What is the blood supply to the liver?
25% coeliac trunk and 75% portal circulation
How does the coeliac trunk supply the liver?
Coeliac trunk -> common hepatic artery (gives off supply to gastroduodenal proper) -> hepatic artery proper
How oxygenated is the portal supply to the liver?
Blood already been processed through intestines so around 50% oxygenated
superior mesenteric vein forms portal vein
superior mesenteric vein formed from inferior mesenteric vein
What does caval mean?
systemic
opposite to portal
porto-systemic anastomoses can also be porto-caval anastomoses
What is the difference between the portal system and the systemic system?
Systemic: heart -> arteries-> coeliac trunk SMA IMA -> proper hepatic artery to liver -> capillary bed around liver -> hepatic vein -> IVC
portal: arteries -> coeliac trunk SMA IMA -> capillary bed in intestines -> hepatic portal vein -> hepatic vein -> IVC
What is a proto-systemic anastomosis?
Where the portal system overlaps with the systemic system allowing the blood to reroute where there is hypertension and blood cannot follow the normal route (collateral flow)
What are the 3 main porto-systemic anastomoses?
- oesophagus: proximal 2/3 of oesophagus drains into vena cava systemically via azygos and hemiazygos veins, distal 1/3 into hepatic portal vein via portal system via left gastric vein
rectus: superior drains into portal system via superior rectal vein at top 1/3, bottom 2/3 drains into systemic system via inferior rectal vein - umbilical: superficial veins of abdomen drain into systemic system into femoral/great saphenous vein then vena cava, in fetal development umbilical vein comes from placenta and some goes to the liver, not in use but still a passageway
How can portal hypertension lead to anaemia and thrombocytopenia?
splenomegaly -> hyperactive spleen -> clears premature RBCs
How does cirrhosis cause ascites?
Liver produces albumin -> cirrhosis of liver means albumin not produced -> no oncotic effect -> fluid not drawn into vessels and leaks into interstitium and abdomen peritoneum = lymphatic retention
How does ascites result in renal sodium retention?
Veins bulge due to lymphatic retention -> body thinks it is going into hypovolemic shock -> aldosterone kicks in -> blood vessels vasoconstrict to compensate -> suprarenal gland releases aldosterone to signal for sodium retention -> water retention -> blood volume expansion -> ascites exacerbated
Where do the internal and external venous plexi drain?
Internal - above pectinate line into the portal system
External - into systemic system
(veins of rectum and anal canal)
What is Murphy’s sign?
to differentiate pain in right upper quadrant
positive in cholecystitis
ask patient to breathe out then place hand below costal margin on RHS mid clavicular line (gallbladder location), patient inspires and normally abdominal contents pushed downward as diaphragm moves down, if patient stops breathing in and comes in contact with fingers may catch a breath, test is positive as gallbladder is tender
same test must not elicit pain on LHS
What is the role of the ampulla of Vater?
hepatopancreatic ampulla/duct
formed from union of pancreatic duct and common bile duct
at the major duodenal papilla
SM sphincters regulate flow of bile and pancreatic secretion into the duodenum and prevents duodenal contents entering ampulla
