Anatomy: Liver and Pancreas

Anatomy: Liver and Pancreas

Liver

The liver (1.5 kg) is the largest solid organ. It has diaphragmatic (superior/anterior) and visceral (inferior) surfaces. The falciform ligament divides it into apparent right and left lobes; the ligamentum teres (obliterated umbilical vein) runs in its free edge. The bare area (bounded by the coronary ligaments and triangular ligaments) is where the liver directly contacts the diaphragm without peritoneum.

The visceral surface has a H-shape formed by: left sagittal fissure (ligamentum teres anteriorly, ligamentum venosum posteriorly), right sagittal groove (gall bladder fossa anteriorly, IVC groove posteriorly), and the porta hepatis (transverse bar of the H) where the portal vein, hepatic artery, and bile ducts enter/exit. Lobes: right (largest), left, quadrate (between gall bladder fossa and left sagittal fissure, inferior to porta hepatis), caudate (posterior to porta hepatis, between ligamentum venosum and IVC groove). Functional division: by hepatic artery and biliary supply, each functional lobe is further divided into 8 Couinaud segments.

Important spaces: hepatorenal recess (Morrison's pouch) — between right lobe of liver and right kidney; most dependent space in supine patient — fluid collects here. Subphrenic recess — between liver and diaphragm.

Biliary Apparatus

Cystic duct (2 mm diameter, ~2 cm long) from gall bladder → joins common hepatic duct → common bile duct (CBD, ~8 mm diameter, ~8 cm long) → joins main pancreatic duct at ampulla of Vater → major duodenal papilla. Calot's triangle: bounded by cystic duct (below), common hepatic duct (medial), and liver edge (superior) — contains the cystic artery and lymph node of Lund; critical surgical landmark for cholecystectomy.

Pancreas

The pancreas (15 cm) lies retroperitoneally. Parts from right to left: head (in the C-curve of duodenum), neck (anterior to portal vein / SMV), body (anterior to aorta and SMA), tail (reaches the splenic hilum). The uncinate process projects posteriorly and passes behind the superior mesenteric artery (SMA) and vein (SMV). The main pancreatic duct (Wirsung) runs through the entire gland, joining the CBD at the ampulla of Vater. The accessory duct (Santorini) drains the superior head and opens at the minor duodenal papilla. The splenic artery (tortuous, along superior pancreatic border) supplies most of the pancreas. Carcinoma of the pancreatic head presents with painless obstructive jaundice (compression of CBD), palpable gall bladder (Courvoisier's sign).