Transcript No. 7

No. 7
1. Liver
2. Gallbladder and Biliary Ducts
3. Pancreas
Section 7 The Liver
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The liver (Hepar) is the largest gland in the body.
It lies mainly in the upper and right parts of the
abdominal cavity below the right half of the
diaphragm and extends to the left of the midline
for about 3 cm. In the male it commonly weights
1.2-1//5 kg, in the female 1.0-1.3kg.
The liver is divided morphologically into a large
right lobe and a smaller left lobe by the
falciform ligament. According to the internal
structure of the lover, it can also be divided into
two halves and then subdivided into some
segments in each half.
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The liver presents two surfaces:
The superior or diaphragmatic surface and
inferior or visceral surface.
The diaphragmatic surface is smooth and shaped
so that it fits the diaphragm. A posterior part of
this surface is devoid of peritoneal covering and
is attached to the diaphragm by areolar tissue,
called the bare area of liver.
The right and left lobes are separated by a fold of
parietal peritoneum called the falciform
ligament, which attaches the liver to the
anterior abdominal wall.
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In the free margin of the falciform ligament is a
fibrous cord called the ligamentum teres
hepatis (round ligament). The ligamentum
teres is the remnant of the fetal umbilical vein
that transported blood from the placenta to the
liver.
The falciform ligament is continuous on the
superior surface of the liver with the coronary
ligament, a fold of the parietal peritoneum that
attaches the liver to the undersurface of the
diaphragm.
The coronary ligament consists of anterior and
posterior layers that are joined at their lateral
margins by right and left triangular ligaments.
Between the two layers of the coronary ligament
is a region called the bare area of the liver. The
bare area, which rests against the diaphragm, is
the only portion of the liver that is not covered
with visceral peritoneum.
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The inferior or visceral surface:
The inferior or visceral surface is slightly concave
and is directed inferiorly and posteriorly.
This surface is marked off by a H-shaped fissures
and grooves.
The cross-bar of the “H” is the porta hepatis,
which may be regarded as the hilum of the liver.
Through the porta hepatis the hepatic portal vein,
the proper hepatic artery and the hepatic nerve
plexus enter the liver, and the right and left
hepatic ducts and some lymph vessels emerge.
These structures are contained beneath the liver
in the right free border of the lesser omentum.
The inferior surface presents four lobes, i.e. left,
right, quadrate and caudate lobes.
Section 8 The Gallbladder and
Biliary Ducts
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Constitution of biliary ducts:
gallbladder and cystic duct,
right and left hepatic ducts,
common hepatic duct,
common bile duct.
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Bile is produced by hepatocytes and collected in
the tyny canaliculi bordered by the hepatocytes
themselves. These bile canaliculi unite to form
the right and left hepatic ducts.
Two hepatic ducts join together to form the
common hepatic duct. The latter is joined by the
cystic duct, the duct of gallbladder, to form the
common bile duct.
The common bile duct is joined by the main
pancreatic duct before the two open together into
the duodenum.
Ⅰ. The Gallbladder
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The gallbladder, a small sac on the inferior
surface of the liver, is 7～10 cm long, 3 cm broad
at its widest part, and 30～50 ml in capacity.
Functions:
It serves as a storage site for bile, which it
receives from the liver.
It also concentrates the bile by reabsorbing
water from it.
Morphology:
The gallbladder consists of the fundus, body,
neck and cystic duct.
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①The fundus is the expanded blind
anterior end of the organ projecting
beyond the inferior margin of the liver.
The point of gallbladder: The gallbladder
lies behind the point where the lateral
edge of the right rectus abdominis crosses
the costal arch.
②The body tapers toward the neck, which
lies in contact with the visceral surface of
the liver.
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③The neck is attached to the liver by areolar
tissue in which the cystic artery is embedded.
The mucous membrane lines the luminal aspect
of the neck and forms oblique ridges, the spiral
folds.
④The cystic duct is up to 5 cm ling and runs
backward and downward from the neck of the
gallbladder. Bile enters and leaves the
gallbla;dder through the cystic duct.
The cystic duct joins with the common hepatic
duct from the liver to form the common bile duct.
Ⅱ. The Common Bile Duct
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It is formed near the porta hepatis by the
junction of the cystic and common hepatic
ducts.
The common bile duct is usually about 7.5
cm long and about 6 mm in diameter. It
lies in the right border of the lesser
omentum, in front of the right edge of the
hepatic portal vein, and on the right of the
proper hepatic artery.
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It runs behind the superior part of the duodenum
and passes in a groove on the posterior surface
of the head of the pancreas. At the left side of
the descending part of the duodenum the
common bile duct comes into contact with the
main pancreatic duct and accompanies it into the
wall of this part of the gut, where the two ducts
usually units to from the hepatopancreatic
ampulla.
The distal constricted end of this ampulla opens
into the descending part of the duodenum on the
summit of the major duodenal papilla.
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The circular muscle around the lower part of the
common bile duct, including the ampulla and the
terminal part of the main pancreatic duct, is
thickened and is called the sphincter of
common bile duct, sphincter of
hepatopancreatic ampulla (Oddi’s sphincter)
and sphincter of pancreatic duct respectively.
When the sphincter relaxes and the smooth
muscle in the wall of the gallbladder contracts,
bile is propelled into the intestine. When the
sphincter contracts, bile from the liver fills the
common bile duct and then enters the gallbladder
via the cystic duct.
Section 9 The Pancreas
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The pancreas is a long, soft, finely lobulated
gland. It located in the upper part of the
abdomen, hidden by many organs.
The pancreas can be divided into head, neck,
body and tail.
The head lies in the C-curve of the duodenum.
Toward the left, the upper part of the head is
continuous with the neck, the lower part of the
head projects the uncinate process which hooks
posteriorly to the superior mesenteric vessels.
The common bile duct lies either in a groove on
the upper and posterior surface of the head of
the pancreas or is embedded in it.
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The neck is about 2 cm long. Its posterior
surface is in relation with the superior
mesenteric vein and the beginning of the
hepatic portal vein.
The body lies above the duodenojejunal
flexure and on the left kidney. It is
separated from the stomach by the
omental bursa.
The tail of the pancreas is narrow, and
usually lies in contact with the inferior part
of the visceral surface of the spleen.
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The pancreatic ducts:
The exocrine secretions of the
pancreas are collected by two ducts,
the main and accessory pancreatic
ducts; both drain into the second
part of duodenum.