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L2.11 liver pancreas peritoneum pdf
1. Liver, pancreas: structure, topography and their
functions. Peritoneum and its derivatives.
Senior Teacher:
Ignatyeva Anastassiya
2. Lecture Plan
⢠The structure of the liver, gall bladder.
⢠Topography of the liver.
⢠Ligaments of the liver.
⢠Segmental structure of the liver.
⢠The structure of the pancreas.
⢠Peritoneum.
5. The Liver
⢠The liver is a reddish brown gland located
immediately inferior to the diaphragm, filling
most of the right hypochondriac and
epigastric regions.
⢠It is the bodyâs largest gland, weighing about
1.4 kg (3 pounds).
6. Gross Anatomy of the liver
⢠The liver is enclosed in a fibrous capsule and,
external to this, most of it is covered by serosa.
⢠The serosa is absent from the bare area
where its superior surface is attached to the
diaphragm.
⢠Surfaces of the liver include:
⢠a diaphragmatic surface in the anterior, superior,
and posterior directions, and
⢠a visceral surface in the inferior direction
7. Diaphragmatic surface of the liver
⢠The diaphragmatic surface of the liver, which
is smooth and domed, lies against the inferior
surface of the diaphragm.
⢠Associated with it are the subphrenic and
hepatorenal recesses.
9. The subphrenic recess
⢠The subphrenic recess separates the
diaphragmatic surface of the liver from the
diaphragm and is divided into right and left
areas by the falciform ligament, a structure
derived from the ventral mesentery in the
embryo.
10. The hepatorenal recess
⢠The hepatorenal recess is a part of the
peritoneal cavity on the right side between
the liver and the right kidney and right
suprarenal gland.
⢠The subphrenic and hepatorenal recesses are
continuous anteriorly
12. Visceral surface
⢠The visceral surface of the liver is covered with
visceral peritoneum except in the fossa for the
gallbladder and at the porta hepatis (gateway to
the liver).
⢠The porta hepatis serves as the point of entry
into the liver for the hepatic arteries and the
portal vein, and the exit point for the hepatic
ducts
13. Structures related to visceral surface
⢠esophagus
⢠right anterior part of the stomach
⢠superior part of the duodenum
⢠lesser omentum
⢠gallbladder
⢠right colic ďŹexure
⢠right transverse colon
⢠right kidney
⢠right suprarenal gland.
16. Associated ligaments
⢠The liver is attached to the anterior abdominal
wall by the falciform ligament and, except for
a small area of the liver against the diaphragm
(the bare area), the liver is almost completely
surrounded by visceral peritoneum
17. Associated ligaments
⢠Superiorly, the falciform ligament forks into
right and left coronary ligaments, which
suspend the liver from the diaphragm.
⢠The round ligament (ligamentum teres),
visible anteriorly at the lower end of the
falciform, is a fibrous remnant of the umbilical
vein, which carries blood from the umbilical
cord to the liver of a fetus.
19. Gross Anatomy of the liver
⢠The liver is superficially subdivided into the
right, left, quadrate, and caudate lobes.
⢠From an anterior view, we see only the large
right lobe and smaller left lobe.
⢠They are separated from each other by the
falciform ligament, a sheet of mesentery that
attaches the liver to the anterior abdominal
wall.
23. Gross Anatomy of the liver
⢠From the inferior view, we also see a squarish anterior quadrate
lobe next to the gallbladder and a tail-like caudate lobe posterior to
that.
⢠An irregular opening between these lobes, the porta hepatis, is a
point of entry for the hepatic portal vein and hepatic arteries and a
point of exit for the bile passages.
⢠All of these blood vessels and bile passages travel in the lesser
omentum. The gallbladder adheres to a depression on the inferior
surface of the liver between the right and quadrate lobes.
⢠The posterior aspect of the liver has a deep groove (sulcus)
occupied by the inferior vena cava
29. Lobes
⢠The liver is divided into right and left lobes by
fossae for the gallbladder and the inferior vena
cava.
⢠The right lobe of liver is the largest lobe, whereas
the left lobe of liver is smaller.
⢠The quadrate and caudate lobes are described as
arising from the right lobe of liver, but
functionally are distinct.
30. Lobes
⢠The quadrate lobe is visible on the anterior part of
the visceral surface of the liver and is bounded on the
left by the fissure for ligamentum teres and on the
right by the fossa for the gallbladder. Functionally it is
related to the left lobe of the liver.
⢠The caudate lobe is visible on the posterior part of
the visceral surface of the liver. It is bounded on the
left by the fissure for the ligamentum venosum and on
the right by the groove for the inferior vena cava.
Functionally, it is separate from the right and the left
lobes of the liver
31. Division of the liver into segments
(Couinaudâs segments)
⢠The liver is divided by the principal plane, which divides the organ into
halves of approximately equal size. This imaginary line is defned by a
parasagittal line that passes through the gallbladder fossa to the inferior
vena cava. It is in this plane that the middle hepatic vein is found.
Importantly, the principal plane divides the left half of the liver from the
right half. The lobes of the liver are unequal in size and bear only little
relevance to operative anatomy.
⢠The traditional eight segment anatomy of the liver relates to the hepatic
arterial, portal, and biliary drainage of these segments. The caudate lobe
is defned as segment I, the remaining segments are numbered in a
clockwise fashion up to segment VIII. The features are extremely
consistent among individuals. From a surgical perspective a right
hepatectomy would involve division of the liver in the principal plane
in which segments V, VI, VII, and VIII would be removed, leaving segments
I, II, III, and IV.
33. Microscopic Anatomy
⢠The interior of the liver is filled with an enormous number of tiny
cylinders called hepatic lobules, about 2 mm long by 1 mm in
diameter.
⢠A lobule consists of a central vein passing down its core,
surrounded by radiating sheets of cuboidal cells called hepatocytes.
⢠Each plate of hepatocytes is an epithelium one or two cells thick.
The spaces between the plates are blood-filled channels called
hepatic sinusoids.
⢠The sinusoids are lined by a fenestrated endothelium that separates
the hepatocytes from the blood cells, but allows blood plasma into
the space between the hepatocytes and endothelium. The
hepatocytes have a brush border of microvilli that project into this
space.
35. Microscopic Anatomy
⢠After a meal, as blood from the intestines circulates
through the hepatic sinusoids, the hepatocytes rapidly
remove glucose, amino acids, iron, vitamins, and other
nutrients for metabolism or storage.
⢠They also remove and degrade hormones, toxins, bile
pigments, and drugs.
⢠Conversely, they secrete albumin, lipoproteins, clotting
factors, glucose, and other products into the blood.
⢠The sinusoids also contain phagocytic cells called
hepatic macrophages, which remove bacteria and
debris from the blood
36. Microscopic Anatomy
⢠The hepatocytes secrete bile into narrow channels, the bile
canaliculi, between the cell plates within each lobule. Bile passes
from there into the small bile ductules between lobules. These
ductules lead ultimately to the right and left hepatic ducts, which
exit the inferior surface of the liver at the porta hepatis.
⢠The hepatic lobules are separated by a sparse connective tissue
stroma. In cross sections, the stroma is especially visible in the
triangular areas where three or more lobules meet. Here, there is
often a hepatic triad of two blood vessels and a bile ductule. The
blood vessels are small branches of the hepatic arteries and hepatic
portal vein
40. Circulation
⢠The liver receives blood from two sources: about 70% from the hepatic portal vein
and 30% from the hepatic arteries.
⢠The hepatic portal vein receives blood from veins of the stomach, intestines,
pancreas, and spleen, and carries it into the liver at the porta hepatis.
⢠All nutrients absorbed by the small intestine reach the liver by this route except for
lipids (transported in the lymphatic system).
⢠Arterial blood bound for the liver exits the aorta at the celiac trunk and follows the
route: celiac trunk â common hepatic artery â hepatic artery proper â right and
left hepatic arteries, which enter the liver at the porta.
⢠These arteries deliver oxygen and other materials to the liver. Branches of the
hepatic portal vein and hepatic arteries meet each other in the spaces between
the liver lobules and both drain into the liver sinusoids. Hence, there is an unusual
mixing of venous and arterial blood in the sinusoids.
⢠After processing by the hepatocytes, the blood collects in the central vein at the
core of the lobule. Blood from the central veins ultimately converges in three
hepatic veins that exit the superior surface of the liver and empty into the nearby
inferior vena cava.
41. The arterial supply to the liver
⢠the right hepatic artery from the hepatic
artery proper (a branch of the common
hepatic artery from the celiac trunk), and
⢠the left hepatic artery from the hepatic artery
proper (a branch of the common hepatic
artery from the celiac trunk).
47. The Gallbladder and Bile Passages
⢠Since the only digestive role of the liver is bile secretion, we
will further trace the flow of bile through organs associated
with the liver.
⢠The most conspicuous of these is the gallbladder, a
pearshaped sac on the underside of the liver that serves to
store and concentrate the bile. It is about 10 cm long and
internally lined by a highly folded mucosa with a simple
columnar epithelium.
⢠Its head (fundus) usually projects slightly beyond the
inferior margin of the liver. Its neck (cervix) leads into the
cystic duct, through which bile enters and leaves the
gallbladder.
48. The Gallbladder and Bile Passages
⢠When the two hepatic ducts leave the porta hepatis, they converge
almost immediately to form the common hepatic duct.
⢠This duct goes only a short distance before joining the cystic duct; it
then becomes the bile duct, which descends through the lesser
omentum to the duodenum.
⢠The bile duct and main pancreatic duct both approach the major
duodenal papilla. Usually, just before emptying into the duodenum,
the two ducts join each other and form an expanded chamber
called the hepatopancreatic ampulla.
⢠A muscular hepatopancreatic sphincter regulates the release of
bile and pancreatic juice from the ampulla into the duodenum
52. The Bile
⢠Bile is a green fluid containing minerals, cholesterol, neutral fats,
phospholipids, bile pigments, and bile acids.
⢠The principal pigment is bilirubin, derived from the decomposition
of hemoglobin. Bacteria of the large intestine metabolize bilirubin
to urobilinogen, which is responsible for the brown color of feces.
⢠In the absence of bile secretion, the feces are grayish white and
marked with streaks of undigested fat (acholic feces).
⢠Bile acids (bile salts) are steroids synthesized from cholesterol. Bile
acids and lecithin, a phospholipid, emulsify fatâ breaking globules
of dietary fat into smaller droplets with more surface area exposed
to enzyme action. Emulsification greatly enhances the efficiency of
fat digestion.
54. The Pancreas
⢠Most digestion is carried out by pancreatic enzymes.
⢠The pancreas is a spongy digestive gland posterior to the
greater curvature of the stomach. It is about 15 cm long
and divided into a globose head encircled on the right by
the duodenum; a midportion called the body; and a blunt,
tapered tail on the left near the spleen.
⢠It has a very thin connective tissue capsule and a nodular
surface. It is retroperitoneal; its anterior surface is covered
by parietal peritoneum, whereas its posterior surface
contacts the aorta, left kidney, left adrenal gland, and other
viscera on the posterior body wall.
55. The Pancreas
⢠The pancreas is both an endocrine and exocrine gland. Its endocrine part is the
pancreatic islets, which secrete the hormones insulin and glucagon. Islets are most
concentrated in the pancreatic tail. Ninety-nine percent of the pancreas is exocrine
tissue, which secretes enzymes and sodium bicarbonate. The exocrine pancreas is
a compound tubuloacinar glandâthat is, it has a system of branching ducts whose
finest branches end in sacs of secretory cells, the acini. The cells of the acini exhibit
a high density of rough ER and zymogen granules, which are vesicles filled with
secretion.
⢠The smaller ducts converge on a main pancreatic duct, which runs lengthwise
through the middle of the gland and joins the bile duct at the hepatopancreatic
ampulla. Usually, there is a smaller accessory pancreatic duct that branches from
the main pancreatic duct and opens independently into the duodenum at the
minor duodenal papilla, proximal to the major papilla. The accessory duct
bypasses the hepatopancreatic sphincter and allows pancreatic juice to be
released into the duodenum even when bile is not.
59. The Pancreas
⢠The pancreas secretes 1,200 to 1,500 mL of
pancreatic juice per day.
⢠This fluid is an alkaline mixture of water,
sodium bicarbonate, other electrolytes,
enzymes, and zymogens.
⢠Zymogens are inactive precursors of enzymes
that are activated after they are secreted.
61. The arterial supply to the pancreas
⢠gastroduodenal artery from the common hepatic artery (a branch of the celiac
trunk),
⢠anterior superior pancreaticoduodenal artery from the gastroduodenal artery,
⢠posterior superior pancreaticoduodenal artery from the gastroduodenal artery,
⢠dorsal pancreatic artery from the inferior pancreatic artery (a branch of the splenic
artery),
⢠great pancreatic artery from the inferior pancreatic artery (a branch of the splenic
artery),
⢠dorsal pancreatic and greater pancreatic arteries (branches of the splenic artery),
⢠anterior inferior pancreaticoduodenal artery from the inferior
pancreaticoduodenal artery (a branch of the superior mesenteric artery), and
⢠posterior inferior pancreaticoduodenal artery from the inferior
pancreaticoduodenal artery (a branch of the superior mesenteric artery).
63. The peritoneum
⢠The peritoneum is a continuous, glistening, and slippery
transparent serous membrane.
⢠It lines the abdominopelvic cavity and invests the viscera.
⢠The peritoneum consists of two continuous layers: the
parietal peritoneum, which lines the internal surface of the
abdominopelvic wall, and the visceral peritoneum, which
invests viscera such as the stomach and intestines.
⢠Both layers of peritoneum consist of mesothelium, a layer
of simple squamous epithelial cells.
64. The parietal peritoneum
⢠The parietal peritoneum is served by the same blood
and lymphatic vasculature and the same somatic nerve
supply, as is the region of the wall it lines.
⢠Like the overlying skin, the peritoneum lining the
interior of the body wall is sensitive to pressure, pain,
heat and cold, and laceration.
⢠Pain from the parietal peritoneum is generally well
localized, except for that on the inferior surface of the
central part of the diaphragm, where innervation is
provided by the phrenic nerves; irritation here is often
referred to the C3âC5 dermatomes over the shoulder
66. The visceral peritoneum
⢠The visceral peritoneum and the organs it covers are
served by the same blood and lymphatic vasculature and
visceral nerve supply. The visceral peritoneum is insensitive
to touch, heat and cold, and laceration; it is stimulated
primarily by stretching and chemical irritation.
⢠The pain produced is poorly localized, being referred to the
dermatomes of the spinal ganglia providing the sensory
fibers, particularly to midline portions of these
dermatomes.
⢠Consequently, pain from foregut derivatives is usually
experienced in the epigastric region, that from midgut
derivatives in the umbilical region, and that from hindgut
derivatives in the pubic region
67. The relationship of the viscera to the
peritoneum
⢠The peritoneum and viscera are in the abdominopelvic cavity. The
relationship of the viscera to the peritoneum is as follows:
⢠Intraperitoneal organs are almost completely covered with visceral
peritoneum (e.g., the stomach and spleen). Intraperitoneal in this case
does not mean inside the peritoneal cavity (although the term is used
clinically for substances injected into this cavity). Intraperitoneal organs
have conceptually, if not literally, invaginated into the closed sac, like
pressing your fist into an inflated baloon.
⢠Extraperitoneal, retroperitoneal, and subperitoneal organs are also
outside the peritoneal cavityâexternal to the parietal peritoneumâand
are only partially covered with peritoneum (usually on just one surface).
Retroperitoneal organs such as the kidneys are between the parietal
peritoneum and the posterior abdominal wall and have parietal
peritoneum only on their anterior surfaces (often with a variable amount
of intervening fat). Similarly, the subperitoneal urinary bladder has
parietal peritoneum only on its superior surface.
68. The peritoneal cavity
⢠The peritoneal cavity is within the abdominal cavity
and continues inferiorly into the pelvic cavity.
⢠The peritoneal cavity is a potential space of capillary
thinness between the parietal and visceral layers of
peritoneum.
⢠It contains no organs but contains a thin film of
peritoneal fluid, which is composed of water,
electrolytes, and other substances derived from
interstitial fluid in adjacent tissues.
69. The peritoneal cavity
⢠Peritoneal fluid lubricates the peritoneal surfaces, enabling
the viscera to move over each other without friction, and
allowing the movements of digestion.
⢠In addition to lubricating the surfaces of the viscera, the
peritoneal fluid contains leukocytes and antibodies that
resist infection. Lymphatic vessels, particularly on the
inferior surface of the constantly active diaphragm, absorb
the peritoneal fluid. The peritoneal cavity is completely
closed in males.
⢠However, there is a communication pathway in females to
the exterior of the body through the uterine tubes, uterine
cavity, and vagina. This communication constitutes a
potential pathway of infection from the exterior.
71. Peritoneal Formations
⢠The peritoneal cavity has a complex shape. Some of the
facts relating to this include the following:
⢠The peritoneal cavity houses a great length of gut, most
of which is covered with peritoneum.
⢠Extensive continuities are required between the parietal
and visceral peritoneum to convey the necessary
neurovascular structures from the body wall to the viscera.
⢠Although the volume of the abdominal cavity is a fraction
of the bodyâs volume, the parietal and visceral peritoneum
lining the peritoneal cavity within it have a much greater
surface area than the bodyâs outer surface (skin); therefore,
the peritoneum is highly convoluted.
72. A mesentery
⢠A mesentery is a double layer of peritoneum that
occurs as a result of the invagination of the peritoneum
by an organ and constitutes a continuity of the visceral
and parietal peritoneum.
⢠It provides a means for neurovascular communications
between the organ and the body wall.
⢠A mesentery connects an intraperitoneal organ to the
body wallâusually the posterior abdominal wall (e.g.,
mesentery of the small intestine).
75. The small intestine mesentery
⢠The small intestine mesentery is usually referred
to simply as âthe mesenteryâ; however,
mesenteries related to other specific parts of the
alimentary tract are named accordinglyâfor
example, the transverse and sigmoid mesocolons,
mesoesophagus, mesogastrium, and
mesoappendix.
⢠Mesenteries have a core of connective tissue
containing blood and lymphatic vessels, nerves,
lymph nodes, and fat
78. An omentum
⢠An omentum is a double-layered extension or fold of peritoneum
that passes from the stomach and proximal part of the duodenum
to adjacent organs in the abdominal cavity.
⢠The greater omentum is a prominent, four-layered peritoneal fold
that hangs down like an apron from the greater curvature of the
stomach and the proximal part of the duodenum. After descending,
it folds back and attaches to the anterior surface of the transverse
colon and its mesentery.
⢠The lesser omentum is a much smaller, double-layered peritoneal
fold that connects the lesser curvature of the stomach and the
proximal part of the duodenum to the liver. It also connects the
stomach to a triad of structures that run between the duodenum
and liver in the free edge of the lesser omentum
82. A peritoneal ligament
⢠A peritoneal ligament consists of a double layer of peritoneum that
connects an organ with another organ or to the abdominal wall.
The liver is connected to the:
⢠Anterior abdominal wall by the falciform ligament.
⢠Stomach by the hepatogastric ligament, the membranous portion
of the lesser omentum.
⢠Duodenum by the hepatoduodenal ligament, the thickened free
edge of the lesser omentum, which conducts the portal triad: portal
vein, hepatic artery, and bile duct.
⢠The hepatogastric and hepatoduodenal ligaments are continuous
parts of the lesser omentum and are separated only for descriptive
convenience.
83. The stomach is connected to the:
⢠⢠Inferior surface of the diaphragm by the
gastrophrenic ligament.
⢠Spleen by the gastrosplenic ligament, which
reflects to the hilum of the spleen.
⢠Transverse colon by the gastrocolic
ligament, the apron-like part of the greater
omentum, which descends from the greater
curvature, turns under, and then ascends to
the transverse colon.
84. A peritoneal ligament
⢠All these structures have a continuous attachment along
the greater curvature of the stomach, and are all part of
the greater omentum, separated only for descriptive
purposes.
⢠Although intraperitoneal organs may be almost entirely
covered with visceral peritoneum, every organ must have
an area that is not covered to allow the entrance or exit
of neurovascular structures.
⢠Such areas are called bare areas, formed in relation to the
attachments of the peritoneal formations to the organs,
including mesenteries, omenta, and ligaments that convey
the neurovascular structures
85. A peritoneal fold
⢠A peritoneal fold is a reflection of peritoneum
that is raised from the body wall by underlying
blood vessels, ducts, and ligaments formed by
obliterated fetal vessels (e.g., the umbilical folds
on the internal surface of the anterolateral
abdominal wall).
⢠Some peritoneal folds contain blood vessels and
bleed if cut, such as the lateral umbilical folds,
which contain the inferior epigastric arteries
88. A peritoneal recess
⢠A peritoneal recess, or fossa, is a pouch of
peritoneum that is formed by a peritoneal fold
(e.g., the inferior recess of the omental bursa
between the layers of the greater omentum,
and the supravesical and umbilical fossae
between the umbilical folds)
89. Subdivisions of Peritoneal Cavity
⢠After the rotation and development of the
greater curvature of the stomach during
development, the peritoneal cavity is divided into
the greater and lesser peritoneal sacs.
⢠The greater sac is the main and larger part of
the peritoneal cavity. A surgical incision through
the anterolateral abdominal wall enters the
greater sac.
⢠The omental bursa (lesser sac) lies posterior to
the stomach and lesser omentum
91. The transverse mesocolon
⢠The transverse mesocolon (mesentery of the transverse
colon) divides the abdominal cavity into a supracolic
compartment, containing the stomach, liver, and spleen,
and an infracolic compartment, containing the small
intestine and ascending and descending colon.
⢠The infracolic compartment lies posterior to the greater
omentum and is divided into right and left infracolic spaces
by themesentery of the small intestine.
⢠Free communication occurs between the supracolic and the
infracolic compartments through the paracolic
gutters, the grooves between the lateral aspect of the
ascending or descending colon and the posterolateral
abdominal wall.
92. The omental bursa
⢠The omental bursa is an extensive sac-like cavity that lies posterior
to the stomach, lesser omentum, and adjacent structures.
⢠The omental bursa has a superior recess, limited superiorly by the
diaphragm and the posterior layers of the coronary ligament of the
liver, and an inferior recess between the superior parts of the layers
of the greater omentum.
⢠The omental bursa permits free movement of the stomach on the
structures posterior and inferior to it because the anterior and
posterior walls of the omental bursa slide smoothly over each
other. Most of the inferior recess of the bursa becomes sealed off
from the main part posterior to the stomach after adhesion of the
anterior and posterior layers of the greater omentum
96. The omental foramen
⢠The omental bursa communicates with the greater sac through the
omental foramen (epiploic foramen), an opening situated posterior to the
free edge of the lesser omentum (hepatoduodenal ligament).
⢠The omental foramen can be located by running a finger along the
gallbladder to the free edge of the lesser omentum. The omental foramen
usually admits two fingers.
⢠The boundaries of the omental foramen are
⢠Anteriorly: the hepatoduodenal ligament (free edge of lesser omentum),
containing the hepatic portal vein, hepatic artery, and bile duct
⢠Posteriorly: the IVC and a muscular band, the right crus of the diaphragm,
covered anteriorly with parietal peritoneum. (They are retroperitoneal.)
⢠Superiorly: the liver, covered with visceral peritoneum.
⢠Inferiorly: the superior or fi rst part of the duodenum.
