Describe the contents of the porta hepatis.
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The porta hepatis is the gateway to the liver and contains several important structures:
Common hepatic duct: Carries bile from the liver.
Hepatic artery: Supplies oxygenated blood to the liver.
Portal vein: Transports deoxygenated blood from the gastrointestinal tract and spleen to the liver.
Autonomic nerve fibres: The sympathetic nerves originate from the coeliac axis, and parasympathetic fibres come from the vagus nerve.
Lymphatic vessels and lymph nodes: Drain lymph from the liver.
Explain the peritoneal attachments of the liver.
The liver is connected to the abdominal wall and diaphragm by various ligaments:
Right triangular ligament: A small fold of peritoneum between the upper and lower coronary ligaments at the posterior bare area of the liver.
Falciform ligament: Runs from the umbilicus to the liver and carries the ligamentum teres.
Left triangular ligament: Connects the posterosuperior part of the left lobe to the diaphragm and continues anteriorly as the left limb of the falciform ligament.
Describe the hepatic veins and their drainage into the inferior vena cava (IVC).
The hepatic veins are responsible for draining blood from the liver:
Three main hepatic veins: Right, central, and left hepatic veins drain into the IVC. The central vein often drains into the IVC via the left hepatic vein, but in some individuals, it may drain directly into the IVC.
Small hepatic venous tributaries: Drain blood directly from the liver's substance and enter the IVC more distally than the main veins.
Zones of drainage: The zones correspond to the right, middle, and left thirds of the liver. The plane of the falciform ligament roughly demarcates the boundary between the left and middle zones.
Outline the anatomical features of the biliary system.
The biliary system includes the structures responsible for bile formation and transport:
Hepatic ducts: The left and right hepatic ducts emerge from the liver and fuse at the porta hepatis to form the common hepatic duct.
Cystic duct: Joins with the common hepatic duct to form the common bile duct (CBD).
Common bile duct: Passes through the hepatoduodenal ligament and opens into the second segment of the duodenum.
Pancreatic duct: The CBD joins the pancreatic duct at the ampulla of Vater, where the sphincter of Oddi controls the release of bile and pancreatic juices into the duodenum.
Describe the anatomical features of the gallbladder.
The gallbladder stores and concentrates bile:
Location: Situated in the fossa between the right and quadrate lobes of the liver.
Capacity: Approximately 50 mL of bile.
Hartmann’s pouch: A small recess near the neck of the gallbladder where gallstones can form.
Vascular supply: Receives blood from the cystic artery, which is a branch of the right hepatic artery.
Venous drainage: Small veins drain into the right portal vein, as there is no distinct accompanying vein for the cystic artery.
Histology: Primarily composed of mucosa lined by mucous-secreting columnar cells. The gallbladder wall also contains smooth muscle, which helps with bile contraction.
Explain the embryological development of the gallbladder and its ducts.
The development of the gallbladder and hepatic system begins early in fetal life:
Liver and hepatic ducts: These structures form from a diverticulum of the ventral wall of the duodenum. This diverticulum differentiates into the liver and the hepatic ducts.
Gallbladder and cystic duct: A second diverticulum forms from the side of the hepatic duct and differentiates into the gallbladder and cystic duct.
