Liver, biliary system, pancreas and spleen by ExzLXq4

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									 Liver, biliary system,
pancreas and spleen
       Long Nguyen
Embryology of the digestive glands
   Liver, gallbladder and pancreas develop from endodermal diverticulae that
    bud from the duodenum in the 4th to 6th weeks
   Liver sprouts first and expands in ventral mesentery
   Cystic diverticulum also in ventral mesentery
   Pancreas arises from a dorsal and ventral bud.
   Ventral pancreatic bud migrates posteriorly to fuse with the dorsal bud.
   Main duct of ventral bud becomes the main pancreatic duct.
         Liver - exam questions
   Write short notes on the segmental
    anatomy of the liver. (9/07, 9/05, 4/05,
    9/04, 9/02)

   Write short notes on the arterial supply to
    the liver and its normal variants. (9/08,
    10/01)
                 Liver
 Lies in right upper quadrant.
 Underlies the thoracic cage.
 Conforms to right dome of diaphragm
 Connected to the diaphragm by the
  falciform and coronary ligaments
Liver - relations
            Surfaces separated by
             inferior border of liver and
             coronary ligament
             posteriorly
            Bare area between the
             reflections of coronary
             ligaments in direct
             contact with diaphragm
             and not covered by
             peritoneum
            Diaphragmatic surface
                Smooth and convex
                Separated from diaphragm
                 by subphrenic recess
Liver – relations (2)
               Visceral (posteroinferior) surface
                    Lies in contact with oesophagus,
                     stomach and lesser omentum on
                     the left
                    Duodenum in midline
                    Right kidney, adrenal and hepatic
                     flexure of the colon on the right

                    H-shaped arrangement of
                     structures
                    Crossbar formed by porta hepatis
                     (portal vein, hepatic artery,
                     hepatic ducts, nerve plexus and
                     lymph vessels
                    Left: ligamentum teres (remnant of
                     left umbilical v.) and ligamentum
                     venosum (remnant of ductus
                     venosum)
             Liver - old lobar anatomy
   Right and left lobes divided by plane through the IVC and gallbladder fossa on (Moore)

   Caudate lobe
         Lies posteriorly between lig. venosum and IVC fossa
         Porta hepatis inferiorly
         Tail-like caudate process connects to right lobe and separates portal vein from IVC

   Quadrate lobe
         Anteroinferior between GB bed and lig. teres
         Porta hepatis superiorly

   Caudate and quadrate lobe considered to be part of left lobe

   Reidel’s lobe (not a true lobe)
         Lower border of the right lobe lateral to the GB may project downwards for a considerable distance as a broad or bulbous process
         Occurs in 5-10% of females and rarely in males
          Liver - vascular anatomy
   Double blood supply from hepatic artery (30%) and portal vein (70%)
   Arterial supply by common hepatic artery branch of coeliac artery.
   Gives off right gastric and gastroduodenal arteries before reaching the liver
    in the free edge of the lesser omentum.
   Divides into left and right hepatic arteries before entering the liver at the
    porta.
   Variants of right hepatic artery below
   Portal vein formed posterior to neck of pancreas by union of SMV and
    splenic vein
      Liver - vascular anatomy (2)
   Right and left lobes functionally independent and defined by arterial
    distribution
   Each supplied by left and right portal v., left or right hepatic arteries
    and drained by left or right hepatic duct (portal triad)
   Quadrate lobe supplied by left hepatic artery
   Caudate lobe supplied by both
               Liver - hepatic veins
   Hepatic veins are intersegmental and do not run with the
    structures of the portal triad
   Right, middle and left hepatic veins drain corresponding
    thirds of the liver
       Middle hepatic vein lies in the principal plane between right and
        left lobes
       Left hepatic vein lies between medial and lateral segments of the
        left lobe
       Right hepatic vein lies between anterior and posterior segments
        of the right lobe
   All drain into the IVC without an extrahepatic course
   Inferior group of small veins from right lobe also drains
    into IVC
Liver - segmental anatomy
    (Couinaud system)
                 Knowledge of segments
                  important in the assessment of
                  location and extent of hepatic
                  pathology as surgery is
                  performed in segmental
                  fashion and distribution of
                  disease determines whether
                  lesions are resectable.
                 The hepatic veins divide the
                  liver into 4 divisions
                 A horizontal plane through the
                  portal vein divides the 4
                  divisions into superior and
                  inferior segments
                 Segments numbered in
                  clockwise direction starting at
                  caudate lobe (segment 1)
        Liver – Lymph drainage and
                 innervation
   Lymph drainage
       Superficial and most deep lymph vessels converge at
        the porta and end in the hepatic lymph nodes (eg.
        Cystic LN near GB neck or LN of omental foramen)
       Hepatic LN’s drain into coeliac LN’s around the
        coeliac trunk, then thoracic duct
       Some deep lymph vessels follow hepatic veins to IVC
        foramen in diaphragm and end in middle phrenic LN’s
   Innervation
       Sympathetic and parasympathetic supply from the
        hepatic plexus, a derivative of coeliac plexus (formed
        from fibres of left and right vagus and right phrenic
        nerves)
Gallbladder and biliary tree – exam
            questions
   Write short notes on the anatomy of the
    gall bladder (9/04)

   Write short notes on the anatomy of the
    biliary tree (excluding the gallbladder) and
    normal variations (4/08, 9/07, 4/05)
       Gallbladder and cystic duct
   Pear shaped sac lies to the right of
    the quadrate lobe in GB fossa on
    the visceral surface of liver
   Concentrates and stores bile
    secreted by the liver
   Cholecystokinin produced by
    intestinal mucosa during digestion,
    passes to GB and causes it to
    contract and release bile
   Fundus, body and neck
   Mucosal membrane arranged into
    spiral folds (valves of Heister) at GB
    neck and cystic duct
            Gallbladder - relations
   Anterosuperiorly
       GB fossa of liver
       Fundus projects from inferior border of liver, located
        at tip of 9th costal cartilage in MCL where lateral edge
        of rectus abdominis meets costal margin
   Posteroinferiorly
       Neck: lesser omentum. Omental (epiploic) foramen
        lies immediately to the left.
       Body: D1
       Fundus: transverse colon
        Gallbladder – blood supply
   Arterial supply
       cystic artery


   Venous drainage
       directly into liver or via a cystic vein
                                  Biliary Tree
   Bile is secreted by hepatocytes into bile
    canuliculi which drain into interlobular bile
    ducts. Progressively larger ducts formed.
   Left and right hepatic ducts emerge from
    porta and merge to form common hepatic
    duct (4cm)
   Joined on the right by the cystic duct from
    the GB to form the common bile duct (8-
    10cm long, 5-6mm diameter)
   Runs in free edge of lesser omentum,
    passes posterior to D1 and head of
    pancreas
   Comes in contact with pancreatic duct on
    the left side of D2
   Usually unite in the duodenal wall to form
    hepatopancreatic ampulla (of Vater)
   Ampulla opens into descending part of
    duodenum at summit of major duodenal
    papilla, 8-10cam from pylorus
        Biliary Duct – blood supply
   Arterial supply
       Proximally: cystic artery
       Middle: right hepatic artery
       Distally: posterior superior pancreaticduodenal a.
   Venous drainage
       Proximally: drainage directly into liver
       Distally: posterior superior pancreaticduodenal v.
   Lymph drainage
       Cystic LN, node of omental foramen, hepatic LN’s
                Biliary Tree - variants
   Accessory hepatic ducts may
    arise in the liver and join the right
    hepatic duct, common hepatic
    duct, common bile duct, cystic
    duct or GB
   Right and left hepatic ducts may
    fail to unite giving a double duct
   Cystic duct
        Absent
        Joins common hepatic duct on the
         left rather than the right
        Joins the right hepatic duct or an
         accessory duct
        Joins the common hepatic duct
         anywhere between the porta and
         the duodenum (low and high
         union)
Variants in union of CBD and
       pancreatic duct
     Pancreas – exam questions

   Write short notes on the anatomy of the
    pancreatic ducts and variations. (9/08)

   Make brief notes on the embryology of the
    pancreas. (10/00)

   What sonographic landmarks are useful in
    identifying the pancreas? (10/00) Describe the
    sonographic appearance of a normal pancreas.
               Pancreas
 Retroperitoneal organ lies transversely
  and slightly obliquely at L1-L2 level
 Transverse mesocolon attached to
  anterior margin
 Exocrine (pancreatic enzymes) and
  endocrine functions (glucagon and insulin)
 Head, neck, body and tail
                Pancreas - Relations
   Head
        Lies in curvature of duodenum
        Anterior to IVC, aorta, right renal vessels and left renal vein
        Uncinate process projects posteriorly and to the left and lies posterior to
         superior mesenteric vessels
        CBD passes posteriorly in a groove or embedded within
   Neck
        Anterior to the union of splenic vein and SMV to form the portal vein
   Body
        Curves over vertebrae and great vessels
        Anterior to the aorta and lies between the coeliac trunk and the SMA
        Splenic vein passes posterior
   Tail
        lies in the splenorenal ligament
        Usually contacts the hilum of the spleen
        Pancreas - Embryology
   Arises from the junction of the primitive foregut
    and midgut as a larger dorsal division and a
    smaller ventral bud
   Ventral bud swings posteriorly to unite with the
    inferior aspect of the dorsal bud trapping the
    superior mesenteric between divisions
   Ventral bud forms the uncinate process
   Duct of the ventral bud forms the proximal end of
    the main pancreatic duct; the distal end of the
    dorsal pancreatic duct forms the remainder.
Pancreas - variations
         Pancreas – blood supply
   Arterial supply
     Head: superior pancreaticoduodenal a. (from
      gastroduodenal artery) and inferior
      pancreaticoduodenal a. (from SMA)
     Body and tail: branches from splenic artery

   Venous drainage
       Mostly splenic v., but also portal v. and SMV
                  Spleen
 Large soft vascular lymphatic organ in the
  left upper quadrant
 Up to 12cm with long axis in line with 10th
  rib
 Arises from mass of mesenchymal cells
  located between layers of dorsal
  mesogastrium.
              Spleen - relations
   Posterior to stomach. Connected to greater curvature by
    gastrosplenic ligament
   Anterior to superior part of left kidney. Connected by
    splenorenal ligament
   Laterally: diaphragm, 9th-11th left ribs
   Tail of pancreas lies at splenic hilum
           Spleen – blood supply
   Arterial supply
     Splenic artery divides into end arteries as it
      enters the spleen
     No anastamoses, hence obstruction of one
      end artery results in area of splenic infarction
   Venous drainage
       Splenic vein
   Lymph drainage
       Pancreaticopsplenic LN’s

								
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