Download Abdominal and peritoneal cavities

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Abdominal and peritoneal cavities
I.
Abdomen part of the trunk below the thorax subdivided into:
A. abdominal cavity: from the diaphragm to an arbitrary plane passing by the terminal
line on the pelvis
B. pelvic cavity: below the terminal line
C. abdominal cavity (proper)
1. contents:
a. parts of the digestive system
(1) stomach
(2) intestines
(3) liver
(4) pancreas
b. parts of the urinary system
(1) kidneys
(2) ureters
c. parts of the autonomic system
d. parts of the circulatory system
(1) abdominal aorta and its branches
(2) inferior vena cava and its tributaries
(3) hepatic portal system
e. parts of the lymphatic system
(1) spleen
(2) cisterna chyli
(3) abdominal portion of the thoracic duct
(4) lymph nodes and lymph vessels
f. suprarenal glands
g. peritoneum: smooth serous membrane that lines most of the abdominal cavity
D. peritoneum
1. parietal peritoneum lines the abdominal cavity
2. visceral peritoneum covers the organs
3. by lining the it with peritoneum, the abdominal cavity is subdivided into the:
a. peritoneal cavity
b. retroperitoneal cavity
4. retroperitoneal organs include:
a. duodenum
b. pancreas
c. kidneys and ureters
d. suprarenal glands
e. ascending and descending colon
f. aorta
g. inferior vena cava
5. besides viscera, the peritoneal cavity contains a small amount of serous fluid that
allows frictionless movement of the intestines
6. important functions of the peritoneum
a. reduction in friction
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b. resistance to infection
c. storage of fat
E. mesentaries are formed by double peritoneal layer that anchors the intestine to the
abdominal wall
1. development of the mesentaries in the adult
a. ventral mesentery
(1) attached only to the caudal part of the foregut
(2) formed by the lower part of the septum transversum (mesodermal)
(3) as a result of the enormous growth of the liver in the septum transversum
the ventral mesentery becomes thin and gives rise to three structures in
relation to the diaphragm and ventral abdominal wall
(a) falciform ligament
i. extends from liver to anterior abdominal wall
ii. its inferior free margin contains the umbilical vein the closes after
birth to form the ligamentum teres
(b) lesser omentum
i. extends from the liver to the lesser curvature of the stomach to
form the gastrohepatic and duodenohepatic ligaments
ii. free margin of the lesser omentum contains
(i) common bile duct
(ii) hepatic artery
(iii) portal vein
(4) part of the ventral mesentery surrounding the liver forms the hepatic
capsule
(5) coronary ligament
(a) between the liver and diaphragm
(b) with rapid and unequal growth of the liver it becomes the right and
left triangular ligaments
(c) area of liver within it (not covered) is the bare area of the liver
b. dorsal mesentery
(1) after the folding of the embryo, it is formed by the reflection of the
peritoneum from the dorsal abdominal wall to the dorsal border of the gut
(a) the caudal part of the foregut and the entire midgut and hindgut
are suspended in the peritoneal cavity by the dorsal mesentery
(2) given the following descriptive name at successive levels
(a) mesoesophagus -related to the esophagus
(b) mesogastrum - related to the stomach
i. formation of the lesser peritoneal sac
(i) intercellular clefts appear in mesogastrum
(ii) clefts then coalesce to form lesser peritoneal sac or omental
bursa
ii. as the stomach rotates on its two axes and the duodenum is
displaced to the right, the peritoneal cavity related to these
structures become incorporated into the lesser sac
iii. dorsal (now left) side of the stomach rapidly enlarges to form its
greater curvature
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iv. greater omentum now is the elongated mesogastrum which
hangs from its greater curvature
(i) covers the intestine
v. later the layers of the greater omentum fuse, obliterating the space
between them and shorten the lesser sac
vi. the lesser peritoneal sac now consists of the superior and inferior
recesses
(i) superior recess -lies posterior to the lesser omentum and
extends behind the caudate lobe of the liver and as far down as
the diaphragm
(ii) inferior recess -lies posterior to the stomach and extend for a
variable distance in the greater omentum
vii. the right free border of the lesser omentum forms the anterior
boundary of the entrance to the lesser sac (the epiploic foramen).
viii. the spleen develops between the layers of the mesogastrium
(greater omentum)
(i) due to the rotation of the stomach the mesogastrum fuses with
peritoneum over the left kidney
(ii) part of the mesogastrium between the spleen and kidney form
the lienorenal ligament
(iii) part of the mesogastrium between the spleen and the stomach
forms the gastrolienal ligament
c. mesentery proper - dorsal mesentery associated with midgut (small
intestine)
(1) rotation of the stomach and duodenum causes the duodenum and
pancreas to become pressed against the posterior body wall
(2) mesoduodenum fuses with peritoneum, thus most of duodenum
and pancreas become retroperitoneal
(3) midgut forms a loop around the superior mesenteric artery
(4) enlargement of the kidneys and liver fills the abdominal cavity and
forces the midgut loop to migrate into the connecting stalk
(5) midgut loop rotates 2700 counterclockwise during the rotation
(6) intestinal loops return into the abdominal cavity first, thereby
pressing the descending and ascending colon to the posterior body
wall
(a) ascending and descending colon become fixed; retroperitoneal
(7) mesentery proper assumes a new line of attachment which passes
from the duodenojejunal junction to the iliocecal junction
d. mesocolon - mesentery associated with the large intestine
(1) mesocolon associated with the ascending and descending colon
fuses with peritoneum of the posterior body wall making the
ascending and descending colon retroperitoneal
(2) mesocolon is associated with the transverse colon is termed the
transverse mesocolon and becomes attached to the anterior
of the pancreas and covers the duodenum
(a) later it fuses with the posterior layer of the greater omentum
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(3) sigmoid colon persists whereas the mesorectum disappears
F. mesenteries in the adult
(1) attachments of the liver
(a) falciform ligament -extends from the anterior abdominal wall and lower
surface of the diaphragm to the anterior surface of the liver
(b) ligamentum teres (round ligament) - located in the edge of the falciform
ligament and contains the obliterated umbilical vein
(c) coronary ligament - attaches liver to the diaphragm
(1) area of the liver enclosed within the coronary ligaments remains devoid
of peritoneal covering and is known as the bare area
(a) right triangular ligament is formed by anterior and posterior layer
of coronary ligament as these come together on the right lobe of the
liver, attaching it to the diaphragm
(b) left triangular ligament - is formed similarly on the left lobe of the
liver, attaching it to the diaphragm
(d) lesser omentum - attaches
(1) to the lesser curvature of the stomach as the hepatogastric ligament
(2) to the duodenum as the hepatoduodenal ligament
(a) forms the anterior wall of the lesser peritoneal sac
(b) free margin of the lesser margin contains:
i. portal vein
ii. hepatic artery
iii. common bile duct
(c) passage under the free margin is the epiploic foramen
(2) dorsal mesentery
a. dorsal mesogastrium is subdivided into:
(1) greater omentum hangs from the greater curvature of the stomach
(a) covers the intestines
(b) gastrocolic ligament is a part between stomach and transverse colon
i. contains the short gastric and left gastroepiploic vessels
(c) due to its high absorptive function is forms adhesions with areas of
inflammation
(d) involved in most of the internal hernias
(e) torsion of the greater omentum interferes with its blood supply
(2) gastrolienal ligament contains left gastroepiploic vessels
(3) lienorenal ligament - contains the tail of the pancreas and terminal
portion of splenic vessels
b. mesentery proper attaches jejunum and ileum to the posterior peritoneal
cavity through its root
(1) root of mesentery extends from the duodenojejunal junction to the
iliocolic junction
(2) contains the superior mesenteric vessels and their branches
c. transverse mesocolon - attaches transverse colon to posterior peritoneal
cavity
(1) attachment runs along the length of the pancreas
(2) contains the middle colic vessels
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d. phrenicocolic ligament - extends from the left colic flexure to the diaphragm
(1) helps support the spleen in an upright position
e. sigmoid mesocolon - attaches the sigmoid colon to the pelvic wall
(1) its attachment crosses the pelvic brim, left ureter, and the division of
left common iliac artery
G. peritoneal recesses (fossa): found in the regions where the peritoneal relationships
of the digestive tract change
1. about the duodenojejunal junction, ileocecal junction, and behind the cecum
2. apparently produced by irregular fusion of mesentery
3. some of these could be produced by blood vessels
4. could be site for intraperitoneal hernias
H. intraperitoneal hernias: protrusion of a part of the gut or the greater omentum
through a naturally occurring or traumatically produced hole in the mesentery
1. incomplete or direct inguinal hernias
a. do not emerge through external inguinal ring
b. may be caused by pressure exerting on a weak portion of the abdominal wall
2. transmesenteric hernias
a. through the epiploic foramen into the omental bursa
b. through any hole in the mesentery
(1) loop of gut simply moves through the defect with peristaltic movements
c. both types can cause acute intestinal obstruction
3. retroperitoneal hernias - represent incarceration of some of the digestive
tract along the posterior body wall
a. retrocolic hernias
(1) located behind the colon or its mesentery
(2) generally form in the pouch created by incomplete fusion of the
ascending and descending colon to posterior wall of abdomen
b. paraduodenal hernias usually are caused by improper rotation of the gut
(1) left paraduodenal hernias lie behind the descending colon
(2) right paraduodenal hernias lie at the base of the mesentery proper
(a) mouth of the sac lies behind the superior mesenteric artery and
iliocolic artery
I. lymphatic drainage
1. numerous lymph nodes are found in the mesentery along the blood vessels
a. lymph from the intestine drains toward the root of the mesentery and
ultimately enters the thoracic duct
2. lymph vessels from the intestine communicate freely with liver lymph vessels
3. cancer of the intestine can spread to the liver through lymphatics or portal vein