Liver and hepatobiliary tract and pancreas Flashcards
Surface anatomy of the liver
-Right upper quadrant
-Lies deep to ribs 7-11
-Extends across epigastrium into left upper quadrant
-Inferior margin palpable at margin of ribs
Positions and relations of biliary tract
-Bile produced by liver, stored in gallbladder, released into duodenum
-Gallbladder lies in gallbladder fossa on visceral surface of liver
-Gallbladder lies anterior and superior to duodenum
Positions and relations of pancreas
-Elongated organ that is positioned transversely in right and left upper quadrants, mainly in epigastric region
-Body crosses midline at L1/2 level
-Head extends to L2/3 level
-Tail of pancreas in near spleen
-Secondary retroperitoneal organ that lies posterior to the stomach
Organs in situ
Lobes of liver
-Anteriorly, falciform ligament separates right and left lobes
-Posteriorly, the caudate lobe and quadrate lobe are part of the right lobe
-Ligamentum teres forms inferior border of falciform ligament
-Falciform ligament extends between liver and anterior abdominal wall
Peritoneal coverings of liver
-Diaphragmatic surface is covered with visceral peritoneum, except posteriorly in the bare area of liver
-Bare area demarcated by upper and lower layers of coronary ligament
-These layers meet on right and left to form right and left triangular ligaments
Impressions of liver
-Liver lies anterior to stomach and duodenum
-Right lobe of liver is close to right kidney and right colic (hepatic) flexure
-Liver is attached to inferior surface of diaphragm so its position is affected by respiration
Porta hepatis
-Considered hilum of the liver
-Lesser omentum extends from porta hepatis to lesser curvature of stomach and first part of duodenum
-Thick free edge of the lesser omentum (hepatoduodenal ligament) encloses the portal triad
What 3 structures make up the portal triad?
-Common bile duct
-Hepatic artery proper
-Hepatic portal vein
Hepatic artery proper
-Continuation of common hepatic artery after it gives off gastroduodenal artery
-Common hepatic artery is 1 of 3 branches of the coeliac trunk
-After porta hepatis, hepatic artery proper divides into right and left branches to supply right and left lobes of liver
Hepatic portal vein
-Liver receives blood from hepatic portal vein (80%) and hepatic artery proper (20%)
-Portal blood contains about 40% more oxygen than venous blood in the systemic circulation and sustains the liver cells (hepatocytes)
-Arterial blood supplies mainly the intrahepatic ducts that convey bile
-Hepatocytes are drained by sinusoids which lead into central vein
-Central veins lead to hepatic veins, which lead to IVC
3 examples of portosystemic anastomoses in the abdomino-pelvic region
-Gastric veins (portal) and oesophageal veins (systemic)
-Patent part of umbilical and its paraumbilical tributaries (portal) and periumbilical veins (systemic)
-Inferior mesenteric vein and superior rectal vein (portal) and middle/inferior rectal veins (systemic)
What does hepatic portal vein do?
-Carries blood from GI organs (spleen, stomach, pancreas, intestines) to be filtered by the liver
-Blood can undergo a flow reversal where hepatic portal vein diverts blood away from liver
Portal hypertension
-In conditions like liver cirrhosis, hepatic portal vein can be obstructed in liver causing pressure to rise in vein and tributaries
-This causes portal hypertension
-This diverts blood away from liver and returns it to supplying vessels draining into hepatic portal vein
-Large volume of blood can cause veins to enlarge (varicose veins)
Effects of portal hypertension
Oesophageal varices - Enlarged veins of oesophagus that could rupture and cause haemorrhage
-Piles/haemorrhoids - Enlarged venous plexuses causing enlargement of the mucosa protruding into the rectal/anal canal
-Caput mudusae - veins of anterior abdominal wall (superficial periumbilical veins) become varicose and resemble snakes
Biliary ducts
-Right and left hepatic ducts drain the right and left lobes of the liver
-These units to form common hepatic duct, joined by cystic duct on right to form the common bile duct
-Bile duct is joined by main pancreatic duct, forming a dilation (hepatopacreatic ampulla), which opens into duodenum through major duodenal papilla
Gallbladder
-Cystic duct connects neck of gallbladder to common hepatic duct
-Gallbladder and cystic duct supplied by cystic artery, which commonly arises from right hepatic artery
Pancreas
-Produces an exocrine secretion (pancreatic juice) that enters the duodenum and endocrine secretions (glucagon and insulin) that enter the blood
-Accessory pancreatic duct opens into duodenum at the minor duodenal papilla
Blood supply of pancreas
-Pancreas being part of foregut and midgut has arterial supply from coeliac trunk (CT) and superior mesenteric arteries (SMA)
-Mainly from branches of splenic artery (CT)
-Other arterial branches arise from superior pancreaticoduodenal arteries (CT) and inferior pancreaticoduodenal arteries (SMA)
-Venous drainage occurs via corresponding pancreatic veins that drain into either the splenic or superior mesenteric veins
Gallstones
-A mass in the gallbladder, cystic duct or bile duct composed of cholesterol crystals
-Large enough gallstones can produce injury to the gallbladder or obstruction of the biliary tract
-The narrower distal end of the common bile duct is a common site of lodged gallstones, which can cause pain
-Gallstones can be asymptomatic
Effects of gallstones
If the stones cause obstruction:
-Cholecystitis (inflammation of gallbladder)
-Pancreatitis (inflammation of pancreas)
