Anatomy & Physiology

anatomy

1. hepatic ducts & CBD

   • w/in portal triads, ducts are supero-medial

     1. artery is supero-lateral whereas vein is inferior

   • L-duct system is longer, drains segments 1-4

   • R-duct system is shorter, drains segments 5-8

   • caudate lobe drains to both L and R duct systems

   • hepatic ducts form a confluence at the hilar plate

     1. extension of Glisson capsule w/no overlying vasculature

     2. ideal for lowering of hilar plate

        • exposure of proximal extra-hepatic biliary tree

   • CBD joins pancreatic duct at ampulla of Vater in D2

   • arterial supply

     1. RHA → passes posterior to CHD then thru hepatocystic triangle

        • cystic artery branches from RHA in this triangle

     2. RHA is aberrant in 20% of population

        • replaced R-hepatic (50%) from PHA or SMA

        • accessory R-hepatic (15%) from SMA, celiac, aorta

        • pass thru portacaval space and ascend lateral to CBD

        • pulsatile structure palpable during Pringle maneuver

        • notable on CT between PV/IVC behind head of pancreas

2. gallbladder

   • 7-10 cm length, holds 30-60 mL bile

   • lays in cystic plate: fibrous inferior surface of segments 4b-5

   • arterial supply

     1. cystic artery → normally arises from RHA w/in hepatocystic triangle

        • may arise from LHA, PHA, CHA, GDA, SMA

     2. can pass posterior or anterior to CBD

     3. lies superior to cystic duct

     4. associated w/Calot node, enlarged in setting of disease

3. cystic duct

   • 1-5 cm, drains most commonly to CBD

   • numerous insertion variations incl. RHD

   • attachment marks end of CHD and start of CBD

physiology

1. hepatocytes directly secrete bile into canaliculi

   • water (97-98%), bile salts (0.2%), bilirubin (0.5%), fats

   • elevation in DBili suggests bile duct obstruction

   • hyperbilirubinemia manifests 1st in the frenulum of tongue

   • TBili > 2.5 can be seen in sclera

   • TBili > 5.0 can be seen in skin

2. CCK > vagal activity → 70% GB evacuation w/in 2h via

   • GB contraction

   • sphincter of Oddi relaxation

3. GB absorbs water and concentrates bile

   • ↑concentration and stagnancy ↑risk of cholelithiasis

4. microbiology

   • E. coli (41%)

   • Enterococcus (12%)

   • Klebsiella (11%)

   • Enterobacter (9%)