What is hepatitis?
Inflammation of the liver is referred to as
hepatitis. It may be infective hepatitis or amoebic
hepatitis.
What is Cirrhosis of the liver?
Under certain conditions liver tissue undergoes
fibrosis and shrinks. This is called cirrhosis of the
liver.
What is liver biopsy?
Liver biopsy needs to be done in certain clinical
conditions. Liver biopsy needle is passed through
right 8th intercostal space. It traverses both the pleural
and peritoneal cavities
Liver biopsies are frequently performed by needle puncture through the right intercostal space
8, 9, or, 10 when the patient has exhaled. The needle will pass through the following structures:
Skin → superficial fascia → external oblique muscle → intercostal muscles → costal parietal pleura
→ costodiaphragmatic recess → diaphragmatic parietal pleura → diaphragm → peritoneum.
Definition of liver
The liver is a large, solid, gland situated in the right
upper quadrant of the abdominal cavity. In the living
subject, the liver is reddish brown in colour, soft in
consistency, and very friable. It weights about 1600 g in
males and about 1300 g in females.
Location of liver
The liver occupies the whole of the right hypo-
chondrium, the greater part of the epigastrium, and
extends into the left hypochondrium reaching up to the
left lateral line. From the above it will be obvious that
most of the liver is covered by ribs and costal cartilages,
except in the upper part of the epigastrium where it is in
contact with the anterior abdominal wall (Fig. 23.19).
The liver is the largest gland in the body. It secretes
bile and performs various other metabolic functions.
The liver is also called the 'hepar' from which we have
the adjective 'hepatic' applied to many structures
connected with the organ.
Surface Marking
In surface projection, the liver is triangular in shape when
seen from the front (Fig. 19.2).
(a) The upper border is marked by joining the
following points: (1) First point in the left 5th
intercostal space 9 cm from the median plane; (2)
second point at the xiphisternal joint; (3) third point at
the upper border of the right 5th costal cartilage in the
right lateral vertical plane; (4) fourth point at the 6th
rib in the midaxillary line; (5) fifth point at the inferior
angle of the right scapula; and (6) sixth point at the 8th
thoracic spine.
(b) The lower border is marked by a curved line
joining the following points : (1) First point at the left
5th intercostal space 9 cm from the median plane; (2)
second point at the tip of the 8th costal cartilage on the
left costal margin; (3) third point at the transpyloric
plane in the midline; (4) fourth point at the tip of the
9th costal cartilage on the right costal margin; (5) fifth
point 1 cm below the right costal margin at the tip of
the 10th costal cartilage; and (6) sixth point at the 11th
thoracic spine.
(c) The right border is marked on the front by a
curved line convex laterally, drawn from a point a little
below the right nipple to a point 1 cm below the right
costal margin at the tip of the 10th costal cartilage.
______________EXTERNAL FEATURES_____________
The liver is wedge-shaped. It resembles a four-sided
pyramid laid on one side
Five Surfaces
It has five surfaces. These are : (1) Anterior, (2) post-
erior, (3) superior, (4) inferior, and (5) right. Out of
these the inferior surface is well defined because it is
demarcated, anteriorly, by a sharp inferior border. The
other surfaces are more or less continuous with
I each other and are imperfectly separated from one
another by ill-defined, rounded borders.
I One Prominent Border
The inferior border is sharp anteriorly where it
' separates the anterior surface from the inferior
surface. It is somewhat rounded laterally where it
separates the right surface from the inferior surface.
The sharp anterior part is marked by (a) an interlobar
I notch or the notch for the ligamentum teres, and (b)
a cystic notch for the fundus of the gall bladder
(Fig. 23.21). In the epigastrium, the inferior border
extends from the left 8th costal cartilage to the right
I 9th costal cartilage.
po Lobes The liver is divided into right and left
lobes by the attachment of the falciform ligament
anteriorly and superiorly; by the fissure for the
ligamentum teres I interiorly; and by the fissure for
the ligamentum I venosum posteriorly.
The right lobe is much larger than the left lobe, and
■forms five sixth of the liver. It contributes to all the I
five surfaces of the liver, and presents the caudate I and
quadrate lobes.
The caudate lobe is situated on the posterior
I surface. It is bounded on the right by the groove for
■the inferior vena cava, on the left by the fissure for the
ligamentum venosum, and interiorly by the porta
■ hepatis. Above it is continuous with the superior
surface. Below and to the right, just behind the porta
hepatis, it is connected to the right lobe of the liver by
Pull the liver downwards and divide the anterior
layers of the coronary and left triangular ligaments.
Identify the inferior vena cava between the liver
and the diaphragm and separate the liver downwards
from inferior vena cava. If the inferior vena cava
happens to be deeply buried in the liver, divide it and
remove a segment with the liver.
Expose the structures in the porta hepatis and
follow them to their entry into the liver. Identify the
viscera related to the inferior surface of the liver and
see their demarcations on the liver. Explore the extent
of right and left pleural cavities and pericardium
related to the superior and anterior surfaces of liver,
though separated from it by the diaphragm.
Cut the structures close to the porta hepatis and
separate all the peritoneal ligaments and folds of the
liver. Remove the liver from the body. Identify its
various borders, surfaces, lobes.
The quadrate lobe is situated on the inferior surface,
and is rectangular in shape. It is bounded anteriorly by
the inferior border, posteriorly by the porta hepatis, on
the right by the fossa for the gall bladder, and on the left
by the fissure for the ligamentum teres
The porta hepatis is a deep, transverse fissure about 5
cm long, situated on the inferior surface of the right lobe
of the liver. It lies between the caudate lobe above and
the quadrate lobe below and in front. The portal vein, the
hepatic artery and the hepatic
Spleen, Pa
DISSECTION
f
Abdomen
plexus of nerves enter the liver through the porta hepatls,
while the right and left hepatic ducts and a few
lymphatics leave it. The relations within the porta hepatis
are from behind forwards the portal vein, the hepatic
artery and the hepatic ducts. The lips of the porta hepatis
provide attachment to the lesser omentum (Fig. 23.23).
The left lobe of the liver is much smaller than the right
lobe and forms only one-sixth of the liver. It is flattened
from above downwards. Near the fissure for the
ligamentum venosum, its inferior surface presents a
rounded elevation, called the omental tuberosity or tuber
omentale.
________________RELATIONS _______________
Peritoneal Relations
Most of the liver is covered by peritoneum. The areas not
covered by peritoneum are as follows : (a) A triangular
'bare area', on the posterior surface of the right lobe,
limited by the upper and lower layers of the coronary
ligament and by the right triangular ligament; (b) the
groove for the inferior vena cava, on the posterior
surface of the right lobe of the liver, between the caudate
lobe and the bare area; (c) the fossa for the gall bladder
which lies on the inferior surface of the right lobe to the
right of the quadrate lobe; (d) the coronary ligament
having superior and inferior layers, which enclose the
bare area of the liver; and (e) the lesser omentum (Figs
23.22, 23.23).
Visceral Relations
Anterior Surface
The anterior surface is triangular and slightly convex. It
is related to the xiphoid process and to the anterior
abdominal wall in the median plane; and to diaphragm
on each side. The diaphragm separates this surface
from the pleura above the level of a line drawn from the
xiphisternal joint to the 1 Oth rib in the midaxfflary line;
and from the lung above the level of a line from the
same joint to the 8th rib. The falciform ligament! is
attached to this surface a little to the right of the median
plane.
Posterior Surface
The posterior surface is triangular. Its middle part
shows a deep concavity for the vertebral column.
Other relations are as follows.
1. The bare area is related to the diaphragm; and to
the right suprarenal gland near the lower end of the
groove for the inferior vena cava.
2. The groove for the inferior vena cava lodges the
upper part of the vessel, and its floor is pierced by the
hepatic veins.
3. The caudate lobe lies in the superior recess of the
lesser sac. It is related to the crura of the diaphragm
above the aortic opening, to the right inferior phrenic
artery, and to the coeliac trunk.
4. The fissure for the ligamentum venosum is very
deep and extends to the front of the caudate lobe. It
contains two layers of the lesser omentum. The
ligamentum venosum lies on its floor. The ligamentum
venosum is a remnant of the ductus venosus of foetal
life; it is connected below to the left branch of the
portal vein, and above to the left hepatic vein near its
entry into the inferior vena cava
5. The posterior surface of the left lobe is marked
by the oesophageal impression.
Superior Surface
The superior surface is quadrilateral and shows a
concavity in the middle. This is the cardiac impression.
On each side of the impression the surface is convex to
fit the dome of the diaphragm. The diaphragm separates
this surface from the pericardium and the heart in the
middle; and from pleura and lung on each side.
Inferior Surface
The inferior surface is quadrilateral and is directed
downwards, backwards and to the left. It is marked by
impressions for neighbouring viscera as follows.
1. On the inferior surface of the left lobe there is a
large concave gastric impression (Fig. 23.24). The left
lobe also bears a raised area that comes in contact with
the lesser omentum: it is called the omental tuberosity.
2. The fissure for the ligamentum teres passes from
the inferior border to the left end of the porta
hepatis. The ligamentum teres represents the
obliterated left umbilical vein.
3. The quadrate lobe is related to the lesser
omentum, the pylorus, and the first part of the
duodenum. When the stomach is empty the quadrate
lobe is related to the first part of the duodenum and to
a part of the transverse colon.
4. The fossa for the gall bladder lies to the right of
the quadrate lobe
5. To the right of this fossa the inferior surface of the
right lobe bears the colic impression for the hepatic
flexure of the colon, the renal impression for the right
kidney, and the duodenal impression for the second
part of the duodenum.
Right Surface
The right surface is quadrilateral and convex. It is
related to the diaphragm opposite the 7th to 11th ribs
in the midaxillary line. It is separated by the
diaphragm from the pleura up to the 10th rib, and from
the lung up to the 8th rib. Thus, the upper one-third of
the surface is related to the diaphragm, the pleura and
the lung; the middle one-third, to the diaphragm and
the costodiaphragmatic recess of the pleura; and the
lower one-third to the diaphragm alone.
[Blood Supply
The liver receives 20% of its blood supply through the
hepatic artery, and 80% through the portal vein. Before
entering the liver, both the hepatic artery and the portal
vein divide into right and left branches. Within the
liver, they redivide to form segmental | vessels which
further divide to form interlobular vessels which run in
the portal canals. Further ramifications of the
interlobular branches open into the hepatic sinusoids.
Thus the hepatic arterial blood mixes with the portal
venous blood in the
sinusoids. There are no anastomoses between adjoining
hepatic arterial territories and hence each branch is an
end artery.
Venous Drainage
Hepatic sinusoids drain into interlobular veins, which
joins to form sublobular veins. These in turn unite to
form the hepatic veins which drain directly into the
inferior vena cava.
The hepatic veins are arranged in two groups, upper
and lower. The upper group consists of three large veins
right, left and middle, which emerge through the upper
part of the groove for the inferior vena cava, and open
directly into the vena cava. The lower group consists of a
variable number of small veins from the right lobe and
the caudate lobe which emerge through the lower part of
the caval groove and open into the vena cava.
Microscopically the tributaries of hepatic veins, i.e.
central veins are seen as, separate channels from those of
the portal radicles.
Lymphatic Drainage
The superficial lymphatics of the liver run on the surface
of the organ beneath the peritoneum, and terminate in
caval, hepatic, paracardial and coeliac lymph nodes.
Some vessels from the coronary ligament may directly
join the thoracic duct.
The deep lymphatics end partly in the nodes around
the end of the inferior vena cava, and partly in the
hepatic nodes.
Nerve Supply
The liver receives its nerve supply from the hepatic
plexus which contains both sympathetic and
parasympathetic or vagal fibres. Nerves also reach the
liver through its various peritoneal ligaments.
Hepatic Segments
On the basis of the intrahepatic distribution of the
hepatic artery, the portal vein and the biliary ducts, the
liver can be divided into the right and left functional
lobes. These do not correspond to the anatomical lobes
of the liver. The physiological lobes are separated by a
plane passing on the antero-superior surface along a line
joining the cystic notch to the groove for the inferior
vena cava. On the inferior surface the plane passes
through the fossa for the gall bladder; and on the
posterior surface it passes through the middle of the
caudate lobe
The right lobe is subdivided into anterior and
posterior segments, and the left lobe into medial and
lateral segments. Thus there are four segments In the
liver: (1) Right anterior, (2) right posterior, (3) left
lateral, and (4) left medial, Some authorities further
subdivide each of these segments into the upper and
lower parts (Fig. 23.26).
The hepatic segments are of surgical importance. The
hepatic veins tend to be intersegmental in their course.
Functions
The functions of the liver: (1) Metabolism of carbohy-
drates, fats and proteins; (2) synthesis of bile and
prothrombin; (3) excretion of drugs, toxins, poisons,
cholesterol, bile pigments and heavy metals; (4)
protective by conjugation, destruction, phagocytosis,
antibody formation and excretion; and (5) storage of
glycogen, iron, fat, vitamin A and D.
_______________HISTOLOGY ______]|
Liver is covered by Glisson's capsule. In the pig there
are hexagonal lobules with portal radicles at 3-5
corners. Each radicle contains bile ductule, branch
each of portal vein and hepatic artery. Central vein lies
in the centre and all around the central vein are the
liver cells or hepatocytes in form of laminae. On one
side of the lamina is the sinusoid and on the ' other side
is a bile canaliculus. Portal lobule seen in j human in
triangular in shape with three central veins at the sides
and portal tract in the centre. The liver acinus is
defined as the liver parenchyma around a preterminal
branch of hepatic arteriole between two adjacent
central veins.
DEVELOPMENT I
From the caudal end of foregut, an endodermalB hepatic
bud arises during 3rd week of development. I The bud
elongates cranially. It gives rise to a small I bud on its
right side. This is called pars cystica andB the main part
is pars hepatica. Pars cystica forms the 1 gall bladder and
the cystic duct which drains intoB common hepatic duct
(CHD).
The epithelial cells of pars hepatica proliferate to I
form the parenchyma. These cells mix up withB
umbilical and vitelline veins to form hepatic sinusoids.
Kupffer's cells and blood cells are formed from the
mesoderm of septum transversum.
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