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    !EVE"#$%ENT #& 'E$T#)I"I*+ S,*E*+

    Surgeons have learned to operate successfull on the liver primaril during the past three

    decades. &or centuries/ the liver 0as a msterious organ 0ith comple anatom/ an

    over0helming num2er of functions/ and an etraordinar capa2ilit to regenerate. Theorgan3s large si4e and a2undant 2lood suppl contri2uted to the respect paid to this organ in

    most civili4ations and operating theaters. Improved understanding of anatom and

    phsiolog/ com2ined 0ith a num2er of recentl developed surgical techni5ues/ led from

    mth and mster to the emergence of the specialt of hepato2iliar surger.

    "aparoscopic cholecstectom rivals "angen2uch3s contri2ution of the open techni5ue (he

    performed the first successful cholecstectom in 1667 0ith respect to surgical

    importance. Not onl has laparoscopic cholecstectom opened the field to other ne0

    procedures/ laparoscopic surger has contri2uted greatl to present interest in shortened

    hospital stas/ lessened costs/ and the rethinking of surgical dogma such as 0ide eposure.The development of hepato2iliar surger culminates in the rise and increased safet of

    hepatic resections and liver transplantation. large num2er of hepatic resections are

    performed 2 speciali4ed surgeons in ma8or centers. The mortalit of elective resection has

    decreased from 79: t0o decades ago to less than 1:. This increased safet follo0s

    improved technolog and understanding of the anatom and phsiolog of the liver. ;ith

    improved safet has come an increased confidence in liver surger/ a 0ide epansion of the

    indications for resection/ and development of other aggressive procedures such as

    croa2lation and chemoem2oli4ation. The most common indication for partial liver

    resection in most centers remains neoplasia.

    spectacular advance in hepatic surger and hepatic therap in general has 2een the

    success of liver transplantation. ;elch performed the first eperimental liver transplant in

    1

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    surger. It is likel the net decade 0ill see consolidated educational programs for the

    training of phsicians and surgeons in this field. unified International 'epato-$ancreato-

    )iliar ssociation has led to the development of the merican 'epato-$ancreato-)iliar

    ssociation ('$)/ 0hich promotes a union of surgeons/ gastroenterologists/

    radiologists/ and other specialists 0ho 0ork 0ithin this dnamic field.

    I. NT#%+ N! $'+SI#"#+

    NT#%+ N! $'+SI#"#+

    %odern concepts of gross hepato2iliar anatom differ considera2l from the anatom

    suggested 2 the ligamentous reflections of the peritoneum/ particularl the falciform

    ligament. &or centuries the right lo2e of the liver 0as defined as all the hepatic parenchma

    to the right of the falciform ligament and the left lo2e as onl the su2stance to the left of

    the ligament. There are no0 t0o ne0 classifications of the gross anatom that have much

    more applica2ilit to surger. The first is the lo2ar sstem used most fre5uentl in the,nited States and often called the merican Sstem. The second is the &rench segmental

    sstem/ 0hich has the most applica2ilit.

    natomic features that ena2le the liver to 2e an important integrator 2et0een the digestive

    sstem and the rest of the 2od include (1 a dual 2lood suppl/ 0ith portal 2lood from the

    splanchnic sstem and the hepatic arterB (7 a specific architectural arrangement of single

    cells and cell masses that facilitates echange 2et0een 2lood and hepatoctesB (@ a

    specific orientation of the hepatoctes that compartmentali4es 2iliar versus 2lood

    path0asB and ( an organi4ed 2iliar ecretor sstem that regulates the enterohepatic

    circulation. In this section aspects of the anatomic organi4ation of the liver are considered

    that are important for 2oth hepatic phsiolog and surger.

    ross natom

    eneral !escription

    The liver lies in the right upper 5uadrant of the a2domen/ 2eneath the diaphragm and

    connected to the digestive tract 2 means of the portal vein and the 2iliar drainage sstem.

    The largest gland in the 2od/ it 0eighs approimatel 1=99 gm. in the adult . The liver

    accounts for 7: of the 2od 0eight of the adult and a2out =: of the 2od 0eight of a

    ne02orn. 'epatic etramedullar hematopoiesis produces the relativel larger liver si4e in

    ne02orns. The normal adult liver resides under the protective ri2 cage. It etends in the

    midclavicular line from as high as the fourth intercostal space do0n to slightl 2elo0 thecostal margin. The gall2ladder lies on the dorsal surface of the liver in a transploric plane.

    peritoneal mem2rane (lisson3s capsule covers the liver and etends as fi2rous septa

    into the parenchma 0ith 2lood vessels and 2ile ducts. The superior surface of the liver

    conforms to the undersurface of the right diaphragm. #nl the liver to the left of the

    falciform ligament contacts the left diaphragm. The inferior surface of the liver touches the

    duodenum/ colon/ kidne/ adrenal gland/ esophagus/ and stomach. $eritoneum invests the

    entire liver ecept for a 2are area under the diaphragm on the posterosuperior surface

    ad8acent to the inferior vena cava and hepatic vein.

    Normal !evelopmentThe liver primordium appears at a2out the third 0eek as a ventral thickening of the

    entoderm at the distal end of the foregut (future duodenum. The ma8or portion of this

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    primordium produces hepatic parenchma and the main 2ile duct. secondar caudal

    proliferation 0ill 2ecome the gall2ladder and cstic duct. The hepatic primordium is

    formed of cellular cords/ 0hich coloni4e the ventral mesogastrium (septum transversum.

    The vitelline (omphalomesenteric veins connected to the digestive tu2e consist of an

    anastomotic net0ork around the duodenum and then cross the septum transversum.

    $roliferation of the entodermal cords forming the hepatic primordium fragments thevitelline veins into a vascular la2rinthD the hepatic sinusoids. The hepatoctes arrange

    themselves into cords surrounding the sinusoidal capillaries.

    ;hen the olk sac disappears/ the vitelline veins regress almost totall and persist onl in

    their mesenteric 2ranches. Caudad to the liver/ the anastomotic net0ork of vitelline veins

    fuse into a single trunk/ the portal vein. In a cranial direction the vitelline veins open into

    the sinus venosus. ;hen the left horn of the sinus venosus disappears/ the right vitelline

    trunk receives the anastomosis of the inferior vena cava and 2ecomes the terminal segment.

    Etension and proliferation of hepatoctes into the entire septum transversum result in

    concurrent fragmentation of the um2ilicoallantoic veins (more lateral to the vitellineveins. The right um2ilicoallantoic vein regresses in the sith 0eek/ leaving the left one to

    drain 2lood coming from the placenta to the liver. The left um2ilical vein drains into the

    left portal vein and passes through a temporar/ short circuit (ductus venosus directl into

    the inferior vena cava. The ductus venosus and left um2ilical vein are o2literated after 2irth

    to form the ligamentum venosus and the ligamentum teres.

    The hepatoctes proliferate/ and the liver protrudes from the transverse septum into the

    a2domen/ 0ith the 2are area a reminder of its origin. )ile ducts differentiate from hepatic

    cells and 8oin the etrahepatic 2iliar sstem/ appearing first in the hilum and then

    spreading peripherall. )ile formation ma 2e evident as earl as the third month.

    Topographic natom

    The reflections of peritoneum that attach the liver to the a2dominal 0all/ diaphragm/ and

    a2dominal viscera determine the topographic anatom of the liver. Three sets of ligaments

    include the follo0ingD

    1. The falciform ligament/ 0hich attaches the liver to the anterior a2dominal 0all from the

    diaphragm to um2ilicus and incorporates the ligamentum teres hepaticus in its dorsal

    2order. In persons 0ith portal hpertension/ the um2ilical vein recanali4es and connects the

    perium2ilical superficial venous sstem 0ith the portal sstem.

    7. The anterior and posterior right and left coronar ligaments/ 0hich in continuit 0ith

    the falciform ligament connect the diaphragm to the liver. The lateral aspects of theanterior and posterior leaves of the coronar ligaments fuse to form the right and left

    triangular ligaments. The area encompassed 2 the falciform/ coronar/ and triangular

    ligaments over the inferior vena cava and under the diaphragm is the 2are area of the liver.

    @. The gastrohepatic and hepatoduodenal ligaments/ 0hich consist of the anterior laer of

    lesser omentum and are continuous 0ith the left triangular ligament. The hepatoduodenal

    ligament contains the hepatic arteries/ portal vein/ and etrahepatic 2ile ducts. It forms the

    anterior 2oundar of the epiploic foramen of ;inslo0 and the communication 2et0een the

    greater and lesser peritoneal cavities.

    &our lo2es of the liver are commonl descri2edD right/ left/ 5uadrate/ and caudate. Thetopographic right lo2e includes a portion of the liver to the right of the falciform ligament

    and the topographic left lo2e portion to the left. The 5uadrate lo2e is a rectangular 8unction

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    on the inferior surface 2ounded 2 the um2ilical fissure on the left/ the gall2ladder fossa on

    the right/ and the portal triad poster