Anatomy of the liver Flashcards
Liver topography
Largest gland in the body
Wedge shaped reddish brown organ
Located below the diaphragm, mostly the right hypochondrium and epigastrium
Main liver functions
Detoxification
Protein synthesis
Production of bile- accessory GI organ
Glycogen storage
Anterior view of the liver
Divided into two main lobes
Left and right
Posterior view of the liver
Two other lobes
Quadrate and caudate
Liver gross anatomy
Surface covered by peritoneum except bare area where it connects with diaphragm
Flaciform and lesser omentum ligaments separate left and right lobes
Porta hepatis divides the quadrate and caudate lobes
Peritoneal folds
Falciform ligament: links diaphragm to upper surface ligamentum teres at lower end
Round ligament: obliterated left umblical vein, extends to umbilicus
Coronary ligaments: links diaphragm to liver
Lesser omentum: links liver to stomach
Lesser omentum
From lesser curvature stomach to porta hepatis
Has a free margin
Encloses: hepatic artery, portal vein, bile duct, lymph vessels
Close to the stomach it encloses the gastric arteries and veins
Blood supply to the gut
Resort to embryological terms: foregut, midgut, hindgut
Each division with specific artery
All midline branches of the abdominal aorta
Blood supply to the liver
Coeliac artery: left gastric, splenic, hepatic
T12/L1 level
Also supplies duodenum and pancreas
No similarly named vein
Hepatic artery variations
Seen in 40-45% of people
Most common cases:
- right hepatic artery replaced to the SMA
- left hepatic artery replaced to the left gastric artery
- trifurcation of the common hepatic artery ( right hepatic artery, left hepatic artery, gastroduodenal artery)
Liver- functional anatomy
Performs a broad range of processes
Metabolism: portal system
Production and secretion of bile
Divided into lobes and segments to perform these
Liver and metabolism
Porta hepatis
- at hilum of liver
- deep fissure- 5cm
- entry/ exit pont for: hepatic portal vein, hepatic artery proper, common hepatic duct, nerves and lymphatics
- once in: branching of vessels
- division of liver into lobes and segments
Hepatic artery
Oxygenated blood
Portal vein (superior mesenteric and splenic)
Deoxygenated blood
Nutrients
Drugs
Toxins
Liver lobule
Liver anatomic lobes are subdivided into segments
Branches of hepatic artery and portal vein carry blood into sinusoids
Branches of bile duct accompany those of hepatic artery and portal vein
All three structure called portal triad and supply each segment
Lobules
Each lobe contains several lobules
The functional units of the liver
Hexagon shaped
Contain hepatocytes (60% liver cells)
Hepatocytes also secrete bile
Portal triads at corners
Hepatocytes- metabolic functions
Synthesis and release plasma proteins into blood; albumin; clotting factors complement cascade components
Deaminates amino acids- urea into blood
Bilirubin to bile pigments
Bile salts- emulsification of fats
Venous drainage of the liver
Mixed blood from the two source in the sinusoids passes through hepatocytes and into the central vein
Central vein is found at the centre of a hepatic lobule
Central veins then drain into the sublobular vein
Sublobular veins then drain into hepatic veins
Portal systemic anastomosis
Communications between some branches of the portal and systemic systems
Portocaval anastomosis
Important if portal vein blocked or passage via liver meets resistance- portal hypertension
Allow collateral return of blood to heart without which subject would die
Anastomosis in abdominal part of oesophagus
Left gastric tributaries with oesophageal branches azygos
Anastomosis in anal canal
Superior rectal anastomoses with middle inferior rectal
Anastomosis in umbilicus
Paraumbilical veins with epigastric veins
Anastomosis in veins of colon, duodenum, pancreas, liver
With renal, lumbar and phrenic
Portal hypertension
Common clinical condition
Obstruction of portal vein
Pressure rises- hypertension
Anastomoses between portal and systemic means backflow to heart then lungs
Varicoses
Caput medusa; oesophageal varices
Portacaval shunt
Reduction of hypertension
Divert blood from portal to systemic
Blood diverted from portal to IVC
Portal vein conveys 70% blood to liver
Largerly been abandoned since the advent of TIPS
TIPS
Transjugular intrahepatic portosystemic shunting
Bile
Secreted by hepatocytes into bile canaliculi
50ml/ hour
Closed sphincter oddi to duodenum-bile flos to gall bladder to be stored and concentrated
Right and left hepatic ducts- relevant lobes
Emerge from porta- unite to form common hepatic duct
Lymphatic drainage
Liver produces vast amount of lymph
Lymph nodes in porta hepatis
Pass to coeliac nodes
Drain to cisteran chyli
Liver trauma
Closely related to lower ribs
Fractured ribs/ penetrating wounds
High vascularisation- severe haemorrhage
Remove portions due to segmental nature liver vessels/ ducts supplying it
- liver biopsies
- metastatic spread
- cirrhosis
