Biliary Diseases

8 Biliary Diseases



Anatomy of the Extrahepatic Biliary System



image

Viscera: Gallbladder and Extrahepatic Ducts


• Anatomy of the biliary system is highly variable, and this includes ducts, arteries, veins, and lymphatics.


Common Hepatic Duct



• Intrahepatic biliary duct systems converge on right and left hepatic ducts.

• Right and left hepatic ducts typically form the common hepatic duct.

• Left duct is usually longer.

• Junction of the ducts may be intrahepatic (e.g., in hepatomegaly).

• Accessory hepatic ducts can occur.

• There may be no common hepatic duct if the cystic duct empties into right and left hepatic duct junction (bile duct branch variant).


Gallbladder



• Normally lies between hepatic segments IV and V, in a ventral fossa between the anatomical right and left lobes

• Ventral surface typically lies in contact with the descending part of the duodenum.

• Peritoneum surrounds fundus and attaches body and neck to the ventral surface of the liver.

• Hepatic surface of the gallbladder has fibrous tissue connections to liver capsule.

• Mucosa
image Columnar epithelium, no submucosa

image Actively absorbs Na+ and water, concentrating bile

• Smooth muscle of the fibromuscular layer is primarily oriented longitudinally.

• Parasympathetic preganglionic innervation from left (anterior) vagus fibers contracts gallbladder and relaxes bile duct sphincter.

• Postganglionic sympathetic fibers from the celiac ganglion are driven by preganglionic fibers from T7-T10 spinal segments traveling in greater splanchnic nerves.

• Visceral afferent fibers (e.g., pain) travel back toward thoracic spinal ganglia, through the celiac plexus and greater splanchnic nerve, alongside incoming sympathetics.


Cystic Duct



• Proximal portion is convoluted; spiral fold keeps the duct open.

• Distal portion is smooth.

• Typical cystic duct joins the common hepatic duct well below the right and left hepatic duct junction.

• Triangle of Calot: classic configuration (shown above) with cystic duct right, common bile duct left, liver above, and right hepatic artery passing through

image

Variations in Cystic and Hepatic Ducts



Cystohepatic Junction



• Classic normal
image High, sub-hepatic origin of the common hepatic duct

image Joined inferiorly, at an angle from the right, by the cystic duct (<3 cm)

image Produces the (common) bile duct some distance above the descending duodenum

• Variations
image Short or absent cystic duct

image Cystic duct parallel to hepatic duct

image Insertion into right hepatic duct

image Low insertion of cystic duct, crossing anterior to common hepatic duct, inserting behind the duodenum

image Low medial insertion of (anterior crossing) cystic duct into bile duct

image Low anterior insertion of (posterior crossing) cystic duct into bile duct

• Anatomical types of cystohepatic junction: angular, parallel, spiral


Ducts of Luschka



• Small biliary ducts that connect directly from liver to the gallbladder

• Potential source of leakage following cholecystectomy


(Common) Bile Duct



• Formed by the union of hepatic and cystic ducts

• Portions: supraduodenal, retroduodenal, pancreatic, intraduodenal

• Bile duct sphincter: smooth muscle surrounding the distal end of the duct, part of the complex sphincter of Oddi


Dimensions



• 4-8 mm diameter normal undilated

• Diameter tends to increase with advanced age.

• Heuristic: normal duct diameter in mm = age/10


Hepatopancreatic Ampulla (Vater)



• Formed by the union of the (common) bile duct and the main pancreatic duct

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Aug 12, 2016 | Posted by in ANATOMY | Comments Off on Biliary Diseases

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