Anatomy of the liver Flashcards
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Approx weight of liver
1.4-1.6kg weight
Location of liver
Located below diaphragm: mostly the right hypochondrium and epigastrium, but extends into left hypochondrium
Main functions of the liver
- Detoxification
- Protein synthesis
- Production of bile - accessory GI organ
- Glycogen storage
Relations of the liver
- Below diaphragm
- Right wrt stomach
- Above the colon
- Overlies gallbladder
Position of liver in relation to ribs
The liver extends from the 5th rib to the bottom of the rib cage
Describe anterior view of liver
Right and left lobes separated by falciform ligament with ligamentum teres
Describe posterior view of liver
- Caudate lobe superior to the quadrate lobe
- Gastric impression on the left lobe and renal impression on the right lobe
What is the porta hepatis
Is a deep 5cm fissure in the interior surface of the liver through which all of the neruovascular structures (except hepatic veins) and hepatic ducts enter or leave the liver
Location of the porta hepatis….
Porta hepatis is located beneath the left portion of the right lobe of the liver, nearer to its posterior surface than its anterior border
What does the porta hepatis divide
The quadrate and caudate lobes
What is the bare area?
Area on the upper part of the right lobe where it is not covered by peritoneum as it connects with diaphragm 5hhm
Which ligaments separate the right and left lobes?
Falciform (ant) and lesser omentum (post) ligaments
Falciform ligament
- Links diaphragm to upper surface liver
- Ligamentum teres(aka round ligament) at lower end
Round ligament
Obliterated left umbilical vein extends to umbilicus
Coronary ligaments
Link diaphragm to liver
Lesser omentum
Links liver to stomach
What are the peritoneal folds?..
- Falciform ligament
- Lesser omentum
- Round ligament
- Coronary ligaments
What is the lesser omentum?
- From lesser curvature stomach to porta hepatis
- Has a free margin (ventral mesentery)
- Close to the stomach
What does the lesser omentum enclose?
Hepatic artery, portal vein, bile duct, lymph vessels and gastric arteries and veins
Blood supply to gut
Foregut - coeliac artery/trunk
Midgut - SMA
Hindgut - IMA
Blood supply to liver
Coeliac artery - left gastric, splenic and hepatic
Level of coeliac artery
T12/L1 level
What does the coeliac artery also supply?
Duodenum and pancreas
In what % of people are hepatic artery variations seen?
40-45%
What are the most common cases of hepatic artery variations?
- Right hepatic artery replaced to the SMA
- Left hepatic artery replaced to the left gastric artery
- Trifurcation of the common hepatic artery into right hepatic, left hepatic and gastroduodenal artery
What are the normal branches of the hepatic artery?
- Right gastric artery
- Gastroduodenal artery
- Hepatic artery proper
What is porta hepatis the entry/exit point for?
- Hepatic artery proper
- Hepatic portal vein
- Common hepatic duct
- Nerves and lymphatics
What are liver anatomic lobes subdivided into?
Couinaud segments
What do the branches of hepatic artery and portal vein carry blood into?
Sinusoids
What are sinusoids?
Small blood vessels
What structures form the portal triad?
Bile duct branch, hepatic artery and portal vein
What are liver lobules?
Hexagon shaped functional units of the liver which contain hepatocytes (60% liver cells)
What do hepatocytes secrete?
Hepatocytes secrete bile
Where are portal triads located in the liver?
At the corners
Functions of hepatocytes
- Synthesis and release of plasma proteins into blood (albumin)
- Deaminates amino acids (release of urea into blood)
- Bilirubin to bile pigment
- Bile salts for emulsification of fats
Where is the central vein found
center of a hepatic lobule
Describe the drainage from central veins
Central veins drain into the sublobular vein which then drains into hepatic veins
What drains into the central vein?
Mixed blood from the two sources (portal and hepatic) in the sinusoids passes through the hepatocytes and into the central vein
What do the hepatic veins ultimately drain into?
IVC
What are portal systemic anastomosis and why are they important?
- Communications between some branches of the portal and systemic systems (portocaval anastomosis)
- Very important if portal vein blocked or passage via liver meets resistance - portal hypertension
- Allows collateral return of blood to heart
Give 4 examples of portal systemic anastomosis
- Abdominal part of oesophagus - left gastric tributaries* with oesophageal branches azygos
- Anal canal - Superior rectal* anastomoses with middle and inferior rectal
- Umbilicus - Paraumbilical veins* with epigastric veins
- Veins of colon, duodenum, pancreas, liver* with renal, lumbar and phrenic
- portal
What is portal hypertension?
obstruction of portal vein which causes an increase in pressure(hypertension)
Signs of portal hypertension
Varicoses and caput medusa
What is the portacaval shunt?
Reduction of hypertension via diversion of blood from portal to systemic
Blood diverted from portal to IVC
What percentage of blood does the portal vein convey to the liver?
70%
Why has the portacaval shunt been abandoned?
Advent of TIPS(transjugular intrahepatic portosystemic shunting)
Where is bile secreted into by the canaliculi?
Bile canaliculi
How much bile is secreted per hour?
40 ml/hr
What do the left and right hepatic ducts merge to form?
common hepatic duct
Describe the biliary tree
- Common hepatic duct joins with the cystic duct to form the common bile duct
- Common bile duct joins with the pancreatic duct hepatopancreatic ampulla of vater
Lymph drainage of the liver
Lymph nodes in porta hepatis passes to coeliac nodes which then drain to cisterna chyli
