anatomy of the stomach and bowels and peritoneal cavity Flashcards
what organs are within the foregut?
oesophagus, stomach, pancreas, liver, gallbladder duodenum (proximal to the entrance of the common bile duct)
what organs are within the midgut ?
duodenum (distal to the entrance of the common bile duct) jejunum ileum caecum apendix ascending colon ⅔ proximal transverse colon
what organs are within the hindgut?
distal ⅓ transverse colon
descending colon
sigmoid colon
upper part of the anal canal (⅓ rectum)
what is the innervation of the foregut?
the greater splanchnic nerve
arises from T5-T9 spinal nerves
what is the innervation of the midgut?
the lesser splanchnic nerve
arises from T10-T11
sympathetic, parasympathetic and sensory supply by superior mesenteric plexus
what is the innervation of the hindgut?
The Least splanchnic nerve
arises from T12 root
sympathetic, parasympathetic and sensory supply via nerves fromthe inferior mesenteric plexus:
- Parasympathetic innervation via the pelvic splanchnic nerves
- Sympathetic innervation via the lumbar splanchnic nerves.
where is pain stimulus in foregut FELT?
foregut innervated by T5-T9 greater splanchnic nerve
so pain felt in upper abdomen
where is pain stimulus in midgut FELT?
midgut innervated by lesser splanchnic T10-T11
so pain felt around umbilicus
where is pain stimulus in hindgut FELT?
hindgut innervated by least splanchnic T12 root
so pain felt in non-hair bearing area immediately above pubis
within which abdominal regions does the stomach lie?
- roughly in the epigastric and umbilical
what are the sections of the stomach?
- cardiac (T11)
- fundus (superior)
- body
- pylorus (antrum,canal,sphincter)
within which part of the stomach is food stored?
the fundus
which is the largest section of the stomach?
the body
where is HCl, intrinsic factor and pepsiongen secreted?
the body of the stomach
which section of the stomach is involved in grinding solid food and mixing it with secretions?
also the widest, most muscular section
the (pyloric) antrum
what is the pyloric sphincter?
- At L1
- ring of thick smooth muscle
- controls outflow of gastric contents(chyme) into the duodenum.
which side is the lesser and which side is the greater curve of the stomach?
lesser: concave, medial (gastro-oesophagus junction to gastro-duodenum junction)
greater: convex, lateral (cardiac notch to pyloric sphincter)
what 2 structures are attached to the lesser curvature of the stomach?
- the lesser omentum
- the hepatogastric ligament
what structure is attached to the greater curvature of the stomach?
the greater omentum
what is the vascular supply to the stomach, on the lesser curvature?
lesser:
R&L gastric arteries
(from the celiac trunk)
what is the vascular supply to the stomach, on the greater curvature?
greater:
R&L gastro-omental arteries
(from the celiac trunk)
what are the 3 main branched of the celiac trunk
- common hepatic
- left gastric
- splenic
explain the veins of the stomach
R&L gastric veins (drain into hepatic portal vein)
short gastric vein
R&L gastro-omental veins (drain into superior mesenteric vein )
what are the sphincters of the stomach?
- Inferior Oesophageal Sphincter
2. Pyloric Sphincter
what level is the Inferior Oesophageal Sphincter at?
what is its function?
T11
It allows food to pass from the oesophagus, through the cardiac orifice, and into the stomach
(is under involuntary control)
what level is the Inferior Pyloric Sphincter at?
what is its function?
It controls (via smooth muscle contractions) the exit ofchymefrom the stomach into the duodenum
what process forces chyme from the pyloric canal into the duodenum?
Gastric peristalsis (overcomes the resistance of the pylorus sphincter)
what are the 3 muscular layers of the stomach?
- outer longitudinal
- inner circular
- innermost oblique
what is the parasympathetic innervation of the stomach?
ANS
- vagus nerve
what is the sympathetic innervation of the stomach?
ANS
- T6-T9 spinal cord segments
- coeliac plexus (via the greater splanchnic nerve)
- some pain transmitting fibres.
describe the lymphatic drainage of the stomach
gastric lymphatic vessels -> gastricandgastro-omentallymph nodes -> coeliac lymph nodes
describe the shape and location of the duodenum
- C shaped tube
- first part of small intestine (from pylorus of stomach to duodenojejunal junction)
- wraps around the head of pancreas
what are the 4 sections of the duodenum?
D1 - superior (the cap)
D2 - descending
D3 - inferior
D4 - ascending
is the duodenum a intraperitoneal or retroperitoneal structure?
D1 - intraperitoneal
rest is retroperitoneal
how can you tell the duodenum has become the jejunum?
once a mesentery develops
describe the spinal level and pathway of the first part of the duodenum
D1 - superior (the cap)
- at L1
- ascends from the pylorus
to what organ is the D1 duodenum attached to?
the liver
via the hepatoduodenal ligament
describe the spinal level and pathway of the second part of the duodenum
D2, descending
- from L1 to L3
- curves inferiorly around head of pancreas
is the second part of duodenum anterior or posterior to:
a. the transverse colon
b. the right kidney
D2
- posterior to transverse colon
- anterior to right kidney
what structure does D2 contain that allows bile and pancreatic secretions in?
major duodenal papilla
describe the spinal level and pathway of the third part of the duodenum
D3, inferior
- L3
- travels laterally to the left
is the third part of duodenum anterior or posterior or inferior to:
a. the aorta & IVC
b. the superior mesenteric artery and vein
c. the pancreas
- crosses over the IVC and aorta (anterior)
- posterior to superior mesenteric artery and vein
- inferior to pancreas
describe the spinal level and pathway of the fourth part of the duodenum
D4, ascending
- L3 to L2
- curves anteriorly upwards, has a sharp flexure, where it joins the jejunum (duodenojejunal flexure)
how is the D4 duodenum adapted to allow the movement of duodenal contents into the jejunum ?
has the suspensory muscle of the duodenum
which contracts and widen angle at duodenojejunal flexure
which parts of the small intestine are intraperitoneal and which are retroperitoneal
intraperitoneal
- the cap of the duodenum
- jejunum
- ileum
retroperitoneal
- rest of duodenum
where does jejunum begin?
duodenojejunal flexure.
where does ileum begin and end?
- no clear external demarcation between the jejunum and ileum
- ileum ends at the ileocaecal junction
what is the ileocecal valve? what is its function ?
- invagination of ileum into the caecum
- at the ileocaecal junction
- can prevent reflux of material back into the ileum
what are the major duodenal papilla/papilla of vater?
point where the dilated junction of the pancreatic duct and the bile duct (ampulla of Vater) enter the duodenum
presence of these marks junction between proximal and distal duodenum
what is the arterial supply to duodenum?
proximal
- gastroduodenal artery
- from coeliac trunk (common hepatic)
distal
- inferior pancreaticduodenal artery
- from SMA
where does the venous drainage of duodenum drain into?
the hepatic portal vein
what is the arterial supply to jejunum and ileum?
branches from SMA (L1)
what are the 3 main branches of the SMA?
right colic
ileocolic
middle colic
what are arcades?
- in small intestine
- loops formed from the branches of the SMA linking via anastomosis
what level does the SMA branch off the aorta?
L1
describe the veinous drainage of the jejunum and ileum
- drained by superior mesenteric vein
- drains into hepatic portal vein
what is the first part of the large intestine? in what section if the abdomen is this found?
- the caecum
- right iliac fossa
what is the first part of the large intestine? in what section if the abdomen is this found?
- the caecum
- in right iliac fossa
what parts of the large intestine are intraperitoneal and retroperitoneal?
intraperitoneal
- caecum
- transverse colon
- signmoid colon
retroperitoneal
- ascending colon
- descending colon
- rectum (not LI)
what is the innervation of the caecum?
superior mesenteric plexus
where is the appendix located?
- at base of caecum
what is the role of the colon?
- to receive digested food from theSI
- from which it absorbs water and electrolytes
- toformfaeces
which parts of the colon are covered by the greater omentum?
ascending
transverse
descending
where does the ascending colon become the transverse colon?
at the 90 degrees right colic (aka.hepatic ) flexure
where the ascending colon meets the right lobe of the liver
where does the ascending colon become the transverse colon?
at the 90 degrees right colic (aka.hepatic ) flexure
where the ascending colon meets the right lobe of the liver
what is the name of the mesentery covering the transverse colon?
- the transverse mesocolon
where does the transverse colon become the descending colon?
- at spleen,
- 90 degree turn inferiorly (left colic/splenic flexure)
does the transverse colon travel anteriorly or posteriorly to the left kidney?
- is retroperitoneal
- but travels anteriorly over left kidney
where does the descending colon become the sigmoid colon?
- as It starts to turn medially
in what abdominal section is the sigmoid colon?
left iliac fossa
which parts of the colon have their own mesenteries?
transverse : the transverse mesocolon
sigmoid: the sigmoid mesocolon
allow for mobility
retro or peri?
describe the arterial supply for the ascending colon
SMA
- the ileocolic → colic, anterior cecal, posterior cecal (all 3 branches supply ascending)
- the right colic arteries
describe the arterial supply for the transverse colon
proximally - SMA
- right colic
- middle Colic
distally - IMA
-left colic
describe the arterial supply for the descending colon
IMA
- left colic
describe the arterial supply for the sigmoid colon
IMA
-sigmoid arteries
which sections of the colon drain into the superior mesenteric vein?
the ascending and transverse
(midgut)
then goes into hepatic portal
which sections of the colon drain into the inferior mesenteric vein?
the descending and sigmoid
(hindgut)
then goes into hepatic portal
what are the 2 portions of the peritoneal cavity ?
greater sac
lesser sac
what are the 2 parts of the greater sac?
superacolic compartment
- ABOVE transverse mesocolon
infracolic compartment
- BELOW the transverse mesocolon
what does the supra colic compartment contain?
- stomach
- liver
- spleen
what does the infracolic compartment contain?
- small intestine
- ascending and descending colon
where is the lesser sac?
ie. omental bursa
posterior to stomach and lesser omentum
how are the greater and lesser sac connected?
via the epiploic foramen of Winslow
where is the epiploic foramen of Winslow ?
posterior to free edge of lesser omentum
```
hepatoduodenal ligament
between liver and duodenum
~~~
is the peritoneal cavity completely closed?
males - yes
females - no (uterine tubes keep it open)
what is the double folding of peritoneam between the rectum and bladder in males called?
the rectovesical pouch
name the double folding of the peritoneum between the rectum and the posterior wall of the uterus (in females)
the Rectouterine pouch (of Douglas)
name the double folding of peritoneum between the anterior surface of the uterus and the bladder (in females)
the Vesicouterine pouch
what is the role of the mucous plug?
in the external opening of the uterus in females
which prevents the passage of pathogens
but allows sperm to enter the uterus.
what are the main differences between the small and large intestine?
- SI is longer, has a narrower diameter, and is more mobile
- SI has villi, circular folds, peyers patches
- LI has taeniae coli, haustra, omental appendices
what are the omental appendices?
pouches of peritoneum
filled with fat
only in large intestine
what are the Taenia Coli ?
- smooth muscle of the colom
- longtiguinal
- 3 strips that run along outer surface
- they contract to shorten the bowel
what are the haustra?
Pouches along the colon caused by taeniae coli being too short
what are the crypts of lieberkuhn?
- found in both SI+LI
- are intestinal glands
- found in between villi in epithelium
what are Paneth cells?
- specialised secretory epithelial cells
- located in the bases of the crypts of Lieberkühn in the SI only
- produce antimicrobial peptides
what are Peyer’s patchers?
- Aggregations of lymphoid tissue
- in ilium of SI
what are the plicae circulares?
- circular folds
- in SI only
- increase SA
what are the Brunner’s glands ?
- tubular mucus glands
- secrete mucus with an alkaline pH, which serves to neutralize chyme from the stomach.
how do you tell the duodenum from the jejunum/ileum?
- only one that contains Brunner’s glands
- broad short villi
how do you tell the jejunum and ileum apart?
jejunum:
- upper left (Ileum is lower right quadrant)
- thicker intestinal wall
- longer vasa recta
- less arcades
- darker red
- way less Peyers patches
