1500g and
receives 1500ml of blood per minute.
Largely covered in a visceral peritoneal
capsule (Glisson's capsule)
Related to
diaphragm, ribs & cc’s (6-10 on R, 6 & 7 on L); see costal
impressions
Remnant of ventral mesogastrium persists as peritoneal folds that attach to the diaphragm.
Posteriorly the IVC deeply grooves the convexity, with the bare area to the R (270)
- bare area related to diaphragm and R adrenal.
Central portion has an H-shaped pattern: R limb = IVC and GB, L limb = fissures for ligamentum teres (from free lower border of falciform) & ligamentum venosum.
cross-piece = porta enveloped by lesser omentum
Related to (with impressions)
stomach and oesophagus, duodenum, hepatic
flexure, R kidney
Has Rouvier's
sulcus, a cleft running between right lobe
and caudate process corresponding to where
the right pedicle of porta enters
liver. A useful landmark for safe
cholecystectomy.
Upper margin: level with xiphisternal joint, 5th intercostal space 7-8cm from midline; on L, 5th rib on R.
R border: ribs 7-11 in mid-axillary line.
Lower border partly lies along right costal margin, crosses in upper abdo wall, hands breadth below xiph.
Suspended from Hepatic veins (entirely intrahepatic) and IVC.
Superiorly, leaves of falciform ligament separate --> anterior leaf of L triangular ligaments and upper layer of the coronary ligament. (270)
Falciform ends ~ at a depression lying between R & L hepatic veins (see below)
Ligamentum TeresContinuation
of the falciform ligament inferiorly
Contains obliterated umbilical vein;
united with L portal vein in embryo. Not
obliterated in 50%, merely collapsed; and can
recanalize in adults (portal hypertension);
hence should be tied if divided (also small
portal veins accompany).
-
runs in a fissure separating
III on L from IV
(quadrate lobe) on R (272)
Ligamentum
Venosum
Fibrous remnant of
the ductus venosus; shunted most of the
blood from the incoming umbilical vein to
the IVC
Runs down the liver to the end of the porta
hepatis, outlining the caudate
lobe (b/n IVC); the two
layers of the lesser omentum attach to the
bottom of the fissure (caudate in lesser
sac).
Attach posterior
surface to diaphragm. The
triangular ligs are sub-parts of the coronary.
Coronary ligament has superior
leaf running to R,
then turning inferiorly to become inferior
leaf.
- at angle of turn = R triangular ligament.
- bare area of liver lies between superior and inferior leaves.
- the line of peritoneal attachment then passes in front of the IVC, then up its left side to the summit of the liver to meet the falciform.
-
Both coronary and falciform
attach to the deep groove for the ligamentum
venosum,
On L the leaves of coronary ligament come together to form L triangular ligament.
- L triangular lig needs dividing to access the abdominal oesophagus and upper stomach.
These ligaments are divided to gain access to liver in resection; care with hepatic veins/IVC.
= fissure between QL in front and CL behind. Two layers of lesser omentum deviate to R over it to enclose the R and L hepatic ducts and R and L branches of hepatic artery and portal vein.
Arrangement: CBD/CHD and HA in front; bile duct is to R and HA tends to overlie PV
-
ie simply VAD with ducts in
front.
- often artery and duct are in the same
plane, with the duct to the right, and
artery overlying portal vein. Significant
variability of relationships and branching
of portal structures into liver.
- artery is
accompanied by lymphatic and nervous tissues
which may neeed to be divided before vessel
can be dissected free.
- portal
tributaries are few up by the liver, but
down by duodenum are several (including pd
veins) and can be troublesome.
Glisson's capsule
condenses around the portal trinity and
surrounds them in a sheath as they enter the
liver.
Can control porta
hepatis by opening the lesser omentum to
their left and slinging around the Foramen
of Windslow; or just clamp if a rapid
pringle required.
(1) Quadrate lobe, bounded by GB on R and umbilical fissure on R; contains portal fissure and portal structures.
(2) Caudate lobe,
posterosuperior to portal fissure with IVC to
R and ligamentum
venosum on L.
Previous
'anatomical classification' was along line of
falciform attachement, fissures of ligamentum
teres and ligamentum venosum.
Surgically,
division is between functional R & L sides of liver,
which runs through middle of GB bed and
groove for IVC. R = 60% of liver; L =
40% usually.
- middle hepatic vein lies on this plane.
There are four main functional sectors: left medial, left lateral and right anterior and right posterior.
- left lateral is the ‘old’ anatomical left liver, to left of ligamentum venosum & falciform
- left medial lies between this and the gallbladder and IVC.
- there is no surface marking to distinguish R anterior and posterior; runs obliquely posteriorly and medially from middle of front of right lobe towards vena caval groove. (RHV in the plane).
I = caudate
lobe; autonomous;
receives portal supply both R and L and drains
autonomously into IVC.
Each sector
divides into 2 parts with one exception
Left lateral sector contains II posteriorly, and III anteriorly.
- the left hepatic vein is between them.
IV = quadrate
lobe (on visceral surface; also
extends superiorly); a left structure
- divided into IVa above and IVb below.
V and VI are the inferior segments of right anterior and posterior segments respectively
VII and VIII are the superior segments of right posterior and anterior segments respectively.
For
memory:
Segments begin inferiorly and spiral anticlockwise and upwards; VIII only one that can’t be seen from below. Any single segment can be resected without endangering blood supply or venous or biliary drainage
-
this also implies one section
may be independently infarcted, mostly true
except some supply across bare area means
few collaterals with phrenics may keep some
sections alive.
On imaging, portal
vein separates inferior and superior
structures, and hepatic vein separates
VII/VIII from IV/V and II/III
Hepatic artery brings oxygenated blood ® R and L branches at porta hepatis.
-
R branch passes
behind the common hepatic duct, and then
divides into ant and posterior.
-
Right hepatic may arise from
SMA (15%) or left gastric (20%) as fairly
common aberrants/accessories (and much
less commonly as 'replaced')
A dangerous variant is the replaced RHA coming
off the gastroduodenal artery, whereby
ligation of the GDA leads to R liver
infarction.
-
If the common hepatic arises
from SMA or aorta instead of CA, passes behind portal vein.
Portal
vein carries venous
blood in ®
R and L branches at the
porta ®
sectoral branches.
Don’t
correspond with portal segmentation; lie
between the four major sectors of the liver.
A large central vein runs in plane between right and left liver, receives from each.
- further laterally lie right and left veins; and the middle frequently joins the left near vena cava
- a separate caudal lobe vein joins as well.
There is
anastomosis between portal venous channels and
azygous system across bare area.
Left =
drains segments II and III; runs across
posterior part of fissre for ligamentum
venosum. Usually receives the middle
hepatic vein before terminating in the IVC.
Middle = Mostly enters L, or uncommonly enters
IVC separately; receives blood from central
segments of liver - IV, VIII, V
Right = largest, but most variable, drains V,
VIII, VII, VI
Cuadiate drains into IVC, usually 1-3 separate
veins.
Liver + GB ® porta hepatis nodes (hepatic nodes) ® via hepatic artery ® pyloric nodes ® coeliac nodes.
Bare area communicates with extraperitoneal lymphatics perforating diaphragm ® posterior mediastinal nodes.
- and similar communications exist along left triangular and falciform ligaments.
Sympathetics and vagus (via coeliac ganglia; run via free edge of lesser o. to enter porta hepatis).
- vagus nerves are from the hepatic branch of anterior vagal trunk.
Central is the hepatic lobule: central vein, cords of hepatocytes separated by sinusoids radiate out.
- portal triads are at the corners of the lobules: br of hep artery, bile ductules, PV.
- Together the arrangement is a portal lobule
Sinusoids are lined by endothelium with fenestrations allowing plasma to enter perisinusoidal spaces around hepatocytes; many of the cells are Kupffer cells (reticuloendothelial, phagocytic).
Bile made by hepatic cells enters biliary canaliculi between apposing hepatocytes ® ductules ® intrahepatic ducts.
Enclosed in Glisson’s capsule, with smaller inner portal canals.
Y-shaped diverticulum from foregut grows into septum transversum; liver develops from its blind ends.
- cranial part of septum transversum becomes pericardium and diaphragm
- caudal part of becomes ventral mesogastrium, liver grows into it.
Original diverticulum becomes right and left bile ducts, blind diverticulum from this ® GB.
Biopsy is carried out through right 8th/9th ICS in mid-axillary line; below lung but through costodiaphragmatic recess and small way through peritoneal cavity.
- must not pass >6cm to avoid the IVC
R lobectomy: divide R lobes, ligating everything, gallbladder taken; middle and left hepatic veins stay.
L lobectomy: divide L lobe with most of caudate & quadrate, back to IVC, middle hepatic veins stay.
- more extensive resections may involve segments V and VIII as well.
- or more restrictive resections involving single segments are undertaken.
Transplantation: remove liver & IVC, suture in new liver and IVC; meanwhile undertaking porto-systemic bypass to left femoral & L axillary veins from portal vein.
- hepatic and biliary end-to-end anastomosis is undertaken, or donor bile duct inserted jejunum
- sometimes (children) the IVC is kept and the new liver is sutured into it.