small intestines Flashcards
what is the function of small intestine ?
main site of nutrients absorption
6-7 meters in length
what are the components of small intestine ?
duodenum
jejunum
ileum
describe duodenum ?
shortest part - 25 cm ( 10 inches ) in length
describe jejunum ?
proximal 2/5th
3 meters
empty of food ( cuz it is always empty of food after death )
describe ileum?
more inferiorly and to the right
often entering the pelvis
what does the ileum end as?
ileocaecal junction
what suspends the jejunum and the ileum ?
Mesentery
are the ileum and jejunum moveable or not?
since they are suspended by the mesentery THEY ARE MOVABLE
why is jejunum always empty of food after death?
intensive peristaltic activity of the jejunum in relative to duodenum and ileum
which parts of the duodenum are intraperitoneal? (INSIDE )
1st
4th
which parts of the duodenum are retroperitoneal ?( behind the peritoneum )
2nd
3rd
which parts of the duodenum are movable?
1st
4th
Cuz they are inside the peritoneum
which parts of the duodenum are fixed and immovable ?
2nd
3rd
they are behind the peritoneum so they are fixed by it and immovable
what is covering the first part of the duodenum?
hepatoduodenal ligament
what is the mesentery ?
fold of tissue ( DOUBLE LAYERS of peritoneum)
in the abdominal cavity
what does the mesentery do?
attaches the intestine to the posterior abdominal wall
provides support stability
pathway for blood and vessels , nerves, lymphatic vessels to reach the intestine
what are the types of mesentery ?
Transverse mesocolon
mesentery proper
mesoappendix
what is the root of mesentery ?
point where the mesentery holds the intestine together
attached to the posterior abdominal wall
the place where blood vessels , nerves and lymphatic travel to and form intestines
Without the root the intestine wont be able to receive blood supply or nerve supply
what is the function of peritoneal fluid?
fluid inside the peritoneum that lubricates the intestine allowing them to move smoothly during digestion
what happens when you have too much peritoneal fluid?
ascites
compress the intestine and mesentery causing discomfort and impairing function
what happens when u have too little peritoneal fluid ?
Friction between intestines causing pain and adhesions
what is a major blood vessel running inside the root of mesentery ?
superior mesenteric artery and vein —-> delivers oxygen and nutrients to the intestine
if the blood supply is cut of off like in cases of mesenteric artery occlusion the intestines become ischemic
what could happen to damage to the mesentery like in trauma or surgery?
restrict intestinal movement leading to adhesion or intestinal obstructions
what covers the mesentery?
peritoneum
if removed —> intestines and mesentery would be exposed to external environment increasing the risk of infections or injury
describe the mesentery around the small intestines?
mesentery starts below the pancreas
goes to posterior abdominal wall
comes back to enclose the small intestines
goes back to posterior abdominal wall again
what is the extension of small intestines?
pyloric orifice to ilioceacal junction
what is the situation/ location of duodenum?
umbilical and epigastric regions
what is extension of duodenum?
from pylorus to the jejunum
pyloric orifice to duodenojejunal flexure
describe the shape of duodenum?
C shaped - around the head of pancreas
shortest and widest part of the small intestine
what is the vertebral level of duodenum?
L1
L2
L3
what is the location of the first part of duodenum ?
Superior duodenum —> Located in the epigastric region
what is the locations of the second part of duodenum ?
descending duodenum
run along the RIGHT side of epigastric and umbilical region
what is the location of the third part of duodenum ?
Horizontal duodenum
Umbilical region crossing from right to left
what is the location of the 4th part of duodenum?
ascending duodenum
Left upper umbilical
left epigastric region
joins the jejunum at the duodenojejunal flexure
duodenum is mostly retroperitoneal and fixed except at?
1st part —–> gastroduodenal junction
4th part —–> duodenojejunal junction
in which quadrant the duodenum is found at ?
Right upper quadrant (RUQ)
cuz it curves around the head of pancreas
what is the level of the 1st part of duodenum?
L1 level
( Pylorus of the stomach lies at the level of transpyloric plane - L1 vertebral level , its the same cuz the 1st part of duodenum is connected to the pylorus of the stomach )
Superior part
what is the vertebral level of the 2nd part of duodenum ?
descends from L1 to L3
descending part
what is the vertebral of the 3rd part of the duodenum?
L3
it is the horizontal one
what is the vertebral level of the 4th part of the duodenum?
Ascend from L3 TO L2
ascending one
Ascends to duodenojejunal flexure
where is the first part of duodenal located?
duodenal cap
lies between the peritoneal folds of the greater and lesser omentum ( between lesser and greater omentum )
So it is intraperitoneal –> moveable
where does the greater omentum attaches?
inferior border of the duodenum
where does the lesser omentum attaches?
attaches to the superior border and connects the duodenum to the liver- –> Hepatoduodenal ligmanet )
also where the lesser omentum end
what are the characteristics of the mucous membrane of the duodenum?
it is in the form of numerous circular folds —> plicae circulares
is plicae circulares present every inside the duodenum?
NO
The first part of the duodenum ( Duodenal cap ) is smooth —> NO plicae circulares
cuz its smooth when given the barium fluid for x ray it will look smooth and rounded outline in xray cuz no plicae circulares
what are the ANTERIOR relations of the 1st part of the duodenum?
Quadrate lobe of the liver
fundus of Gallbladder
in the cadaver it looks green cuz of bile
what are the POSTERIOR relations of the 1st part of the duodenum?
Common bile duct
gastroduodenal artery —->( from the common hepatic artery and gives right gastroepiploic artery and superior pancreaticoduodenal artery)
portal vein
gallbladder on the right side then portal vein in the middle and gastroduodenal artery is on the left
gallbladder/ portal vein / gastroduodenal artery
what are the SUPERIOR relations of the 1st part of the duodenum?
Omental foreman
( opening into the omental bursa aka the lesser sac ) —> epiploic foraman
what is the INFERIOR relation of the 1st part of duodenum?
Head of the pancreas
Remember duodenum is C shape around the head of pancreas
you also see little bit pancreas in the posterior aspects
what is found interiorly of the 2nd part of the duodenum?
Plica circularis
major duodenal papilla
Minor duodenal papilla
describe plica circularis?
mucous membrane thrown into permanent circular folds
it increases surface area
describe major duodenal papilla?
papilla - inward projection of mucosa
Eminence for the common opening for the bile and main pancreatic ducts
seen about halfway down in the postero medial wall
pretty much opening for ducts ( pancreas and bile )
what do the ducts unit to form inside the 2nd part of duodenum?
hepato- pancreatic ampulla of vater
describe minor duodenal papilla?
opening for ACCESSORY pancreatic duct ( NOT THE MAIN ONE )
2 CM ABOVE THE MAJOR ( opening for main pancreatic duct and bile )
what are the ANTERIOR relations of the 2nd part of the duodenum?
Right lobe of liver
Gall bladder
Transverse colon
coils of jejunum
what are the POSTERIOR relation of the 2nd part of the duodenum
Right kidney HILUM and ureter
Right kidney vessels
what are the MEDIAL relations of the 2nd part the duodenum?
Head of pancreas
Anastomoses of the superior and inferior pancreatico duodenal vessels
common bile duct and pancreatic duct
what are the LATERAL relation of the 2nd part of the duodenum?
Hepatic flexure of colon
what is crucial in surgeries or excision of pancreas?
make sure the arteries are intact because they supply the duodenum as well
where does the superior pancreaticoduodenal artery come from ?
gastroduodenal artery
where does inferior pancreaticoduodenal artery come from?
first branch of the superior mesenteric artery
what is the usage of endocscopic retrograde cholangiopancreatogram ?
to check if common bile duct is blocked or not
we use the major duodenal papilla a land mark to find the duct
what are the ANTERIOR relations of the 3rd part of the dudoenum ?
Covered by peritoneum except the root of mesentery
Crossed by superior mesenteric vessels
what are the POSTERIOR relations of the 3rd part of the duodenum?
from right to left :
Right psoas major
Right Ureter
Right gonadal vessels
IVC
abdominal aorta
Origin of the inferior mesenteric artery
what is the SUPERIOR relation of 3RD part of the duodenal?
Head of pancreas with inferior pancreaticoduodenal vessels ( which anastomosis with the superior ones at the 2nd part )
what are the INFERIOR relations of the 3RD part of the duodenum?
Coils of jejunum
what is the transverse mesocolon attached to?
Pancreas
if we cut it then we detach the transverse colon along with the mesocolon ( fold of the peritoneum )
what is the mesentery attached to?
the entire jejunum and ileum extending from duodenojejunal flexure to the ileocecal junction in the right lower quadrant
what does the mesentery proper contain?
it is the suspending structure that contains blood vessels like superior mesenteric artery . lymphatic vessels, nerves
Which travel through this root to supply the jejunum and ileum
what is the extension of the 4th part of the duodenum ?
it extends from the FRONT of the aorta to the duodenal jejunal flexure
what supports the duodeno-jejunal flexure?
MUSCLE OR LIGAMENT OF TREITZ —> suspensory muscle of the duodenum
composed of skeletal muscle from diaphragm smooth muscle from the duodenal wall and fibrous tissue
what is the function of the muscle/ligament of treitz?
Contraction widens the angle of the duodeno jejunal flexure
facilitating movement of the intestinal contents
where does the foreign bodies impact ?
duodeno jejunal flexure
because the sharp angulation at duodenojejeunal flexure
what are other likely sites of ingested foreign body impactions?
duodenal loop
duodenojejunal junction
appendix
ileocecal valve region
where does duodenal peptic ulcer mostly occur?
posterior wall of the duodenal cap
what happens in duodenal peptic ulcer?
it causes perforation
perforation allow the content to enter the peritoneal cavity causing peritonitis
what artery can be damaged in duodenal peptic ulcer?
Gastroduodenal artery
Erosion of gastroduodenal artery —> posterior relation of the superior part of the duodenum by ulcer results in severe hemorrhage in the PERITONEAL CAVITY
what is the location para duodenal fold and fossa?
lies to the left of the ascending part of the duodenum
paraduodenal fossa are peritoneal folds
what raises the para duodenal fold ?
inferior mesenteric vein
ascending left colic artery is also there
what could happen if a loop of intestine enter the paraduodenal fossa?
strangulate —> paraduodenal hernia
it could obstruct the vein and theres danger dividing the vein if the peritoneum has to be divided at the operation to free hernia
what could cover the superior and inferior duodenal fossa?
horizontal folds
the mouth of these fossas face each others
describe the jejunum and ileum?
mobile part of the small intestine suspended by the mesentery extending from the duodenum
duodojejunal junction to the colon ( ileocecal junction)
describe the mesentery of the small intestine ?
fan shaped double fold of peritoneum that suspends the jejunum and ileum form the posterior abdominal wall
what is the extension of the root of mesentery?
it is 6 inches
in the posterior abdominal wall in an oblique direction
from the DUODENO JEJUNAL JUNCTION on the left side to the RIGHT SACROILIAC JOINT
what does the mesentery cross?
3rd part of the duodenum
abdominal aorta
right ureter
right psoas muscle
what is the content of the mesentery?
Superior mesenteric vessels
Lymph nodes
Fat
autonomic nerves
what is mesentery connected to superiorly ?
junction between duodenum and jejunum
what is volvulus ?
loop of small intestine and its mesentery become twisted
the vessels in the mesentery and the gut itself are obstructed
what is the difference between jejunum and ileum?
no sharp demarcation
Gradual change in the number of :
Length and location : the jejunum is shorter and thicker and lie above and to the LEFT of the ileum ( LEFT UPPER QUADRANT )
Ileum lies in the RIGHT LOWER QUADRANT ( opposite to jejunum )
Plicae circularis :
Crescentic transverse folds of mucosa - increase the surface area for absorption
Large and close together in the proximal half of the jejunum
Gradually disappearing almost wholly in the distal ileum ( so less and less as we go down )
More lymph nodes are in the ileum
Arrangement of blood vessels in the mesentery :
Jejunum : few arcades and long vasa recta
Ileum : many arcades and short vasa recta ( opposite )
Width of the lumen and thickness of wall :
Jejunum is wider and thicker walled than the ileum
Thick wall of jejunum feels double compared to the thin ileum wall
Lymphoid tissue :
Ileum has more aggregation of lymphoid tissue
Fat in mesentery :
Ileum has more fat in its mesentery
what is the blood supply of the foregut ?
celiac trunk
what is the blood supply of the midgut ?
superior mesenteric artery
what is the blood supply of the hindgut ?
Inferior mesenteric artery
what is the origin of superior mesenteric artery?
Abdominal aorta at the level of L1 vertebrae
what is the course of superior mesenteric artery?
descends to the right behind body and infront of the uncinate process of the pancreas
Crosses in front of the 3rd part of the duodenum
Enters the root of mesentery of the small intestine
Ends in the right iliac fossa by anastomosing WITH ILEOCOLIC BRANCH ( terminal branch of the mesenteric artery on the other side )
what are the branches of the superior mesenteric artery ON THE LEFT SIDE?
jejunal and ileal branches
about 15-20 number arising from the left side
form loops or arterial arcades which rise to straight arteries ( VASA RECTA )
Occlusion of a straight artery may lead to infarction of the segment supplied but occlusion of arcade vessels usually without effect —–> because theres numerous anastomotic connection so no need to worry about occlusion
what are the branches of superior mesenteric artery on the RIGHT SIDE ?
supply the large intestine
middle colic
inferior pancreaticoduodenal artery
right colic
ileocolic ( anastomosis with the terminal branch of the superior mesenteric artery of the other side )
what is the course of the superior mesenteric vein?
Runs to the right of the superior mesenteric artery in the root of mesentery
Ends posterior to the neck of the pancreas where it units with the splenic vein to form portal vein
what is the lymph drainage of the duodenum?
accompany the superior and inferior pancreaticoduodenal vessels
CELIAC AND SUPERIOR MESENTERIC NODES
What is the lymph drainage of jejunum and ileum?
to superior mesenteric nodes via lymph nodes close to intestinal wall and INTERMEDIATE NODES in the mesentery
what divides the foregut and midgut?
major duodenal papillae
what is the parasymphatic supply of the small intestine ?
vagal
what is the sympathetic supply of small intestine ?
Spinal cord segment T9-T11
what is the function of sympathetic supply ?
vasoconstriction
inhibit peristalsis
Transmit pain and usually to the umbilical region
why does small intestine pain is felt in the umbilical region of the abdomen?
Because T9 - T11 spinal segments correspond to the mid abdomen around the umbilical region
what are the nerves of the sympathetic nerves?
Greater splanchnic nerve
Lesser splanchnic nerve
Last splanchnic nerve
Lumbar splanchnic
Sacral splanchnic
describe greater splanchnic nerve?
preganglionic fibers arise from T5- T9/10 ganglia
Fibers in the higher roots maybe traced upward in the sympathetic trunk as far as T1/T2 ganglia
End in the celiac ganglion + superior mesenteric ganglion + Suprarenal
describe lesser splanchnic nerve?
Preganglionic fibers arise from T9 AND T10/T11
End IN THE AORTICORENAL GANGLION + Celiac and superior mesenteric ganglion
describe the least splanchnic nerves?
Preganglionic fibers arise from the last T12
end in the aorticorenal and superior / inferior mesenteric ganglion
describe the lumbar splanchnic nerve?
carry sympathetic from L1-L2 level of spinal cord to prevertebral plexus —> inferior mesenteric and inferior hypogastric
describe sacral splanchnic nerve?
Sympathetic from L1-L2 level of spinal cord
down the sympathetic trunk to the sacral ganglia in the sympathetic chain
on the route to the hypogastric plexuses
what is the origin of sympathetic nerve fibers??
T5-L2
what is the origin of CNS parasympathetic??
Cranial nerve 10 –> vagus nerve
S2-S4
what is the function of splanchnics nerves?
transport autonomic fibers from the sympathetic trunk ( Sympathetics ) or spinal nerves ( para) to the prevertebral plexus
describe parasympathetic splanchnic nerve ?
pelvic splanchnic :
Transport parasympathetic fibers from S2-S4 spinal nerves to the prevertebral plexus –> inferior hypogastric plexus
what is intussusception ?
proximal segment of intestine invaginates into the portion of intestine immediately distal to it
what is the most frequent location of intussusception ?
ileocolic junction
what does intussusception cause?
swelling , reduced blood flow , obstruction and tissue damage —> perforation
how is intussusception diagnosed ?
barium enema
the pressure may unfold the bowl
