Download Stomach Functions, J shaped bag! Gastric emptying

Stomach
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Functions, J shaped bag!
Gastric emptying- takes upto 6 hours for solid food to empty! Water- upto 2 hrs
Body
Greater curvature –lateral convex border. Point of attachment for gastrosplenic, gastrocolic
and gastrophrenic ligaments of the greater omentum
Lesser curvature- medial concave border of stomach and attachment site for hepatogastic
ligament of lesser omentum. Short than greater curvature.
Cardia – surrounds opening of oesophagus into stomach
Fundus- dilated part of stomach that is positions superior to cardia. Can become dilated with
fluid or gas
Body- largest part, positioned between fundus and pyloric antrum
Gastric folds/rugae- They provide the stomach with increased surface area for nutrient
absorption. When food enters the stomach, thesefolds stretch outward.
Cardial notch- between fundus and cardia
Angular incisures (notch) – sharp notch along lesser curvature between body and pyloric
antrum
Pylorus (pyloric antrum + sphincter and canal) - two parts- antrum: opening to stomach,
canal: opening to duodenum. Canal ends at pyloric orifice (L1 vertebral level) which
surrounded by sphincter (band of muscle) – regulates flow of chyme into the duodenum
-know relations
Arterial supply stomach: all from coeliac trunk
• Left gastric artery from the coeliac trunk;
• Right gastric artery from the hepatic artery proper; (join at lesser curvature)
• Left gastro-omental artery from the splenic artery (anatomose at greater curvature)
• Right gastro-omental artery from the gastroduodenal artery.
Small intestines – longest part of GIT – DJ I.. Primary function: digest and absorb nutrients
Duodenum- first and shortest part, responsible for breakdown of food. C-shaped. Widest lumen and
is retroperitoneal along the majority of its length except the proximal part which is suspended by
hepatoduodenal ligament. Continuation of pyloric canal and ends at hepatoduodenal junction.
4 parts:
• Superior (first) – begins at the pylorus and runs upwards and backwards across the L1 vertebral
body to the right of the midline;
• Descending (second) – runs vertically down the right side of L2 and L3 vertebrae. The bile duct and
main pancreatic duct penetrate the medial wall about half way down its medial border;
• Horizontal (third) – runs horizontally to the left across the L3 vertebral body, inferior vena cava
and aorta. The superior mesenteric artery and vein are positioned anterior;
• Ascending (fourth) – runs from the left border of the L3 vertebra to the superior border of L2. It
passes to the left of the aorta and merges with the jejunum at the duodenojejunal junction.
Duodenal-jejunal junction - suspended by a peritoneal fold that contains muscle fibres from the
right crus of the diaphragm – the suspensory muscle of the duodenum or ligament of Treitz. This
junction is at an acute angle and can be widening with contraction of suspensory muscle. Widening =
passage of food through Small intestine.
Arterial supply:
Branches of coeliac trunk and SMA. Due to duodenum making transition of foregut to midgut at level
or major duodenal papillae- upper part by coeliac trunk and lower part by SMA.
The first and second parts are supplied by the:
• Gastroduodenal artery from the coeliac trunk;
• Supraduodenal and superior pancreaticoduodenal artery from the gastroduodenal;
The third and fourth parts are supplied by the:
• Inferior pancreaticoduodenal artery from the superior mesenteric artery.
jejunum, ileum – digesting and absorbing nutrients from ingested food.
-freely mobile coils and have distinctive characterisits. Suspended from posterior body wall by
mesentery (flower like) which runs diagonally from left side of the L2 vertebrae to R sacroiliac joint.
Root of mesentery is shorter than long free edge which surroundes jej and ileum.
Arterial supply:
Jej and ileum- supplied by SMA. Artery and branches run between the 2 layers that form the
mesentery. Originating from the left are the jejunal branches PROXIMALLY and ileal branches
DISTLLY. They then anatomsse along the length of jej and ileum to form arterial arcades – from these
are straight arteries : VASA RECTA. Most distal ileum is supplied by ileocolic artery.
Coeliac trunk
Splenic, hepatic, left and right gastric, left and
right gastroomental, gastroduodenal
Gastric folds, pyloric antrum, canal and sphincter
Superior mesenteric artery
Jejunal and ileal branches, ileocolic, right colic,
middle colic
Large intestines- absorb water and electrolytes from digested food and also store faeces prior to
defecation. U Shaped. Ceacum, ascending colon, transverse colon, descending colon, sigmoid colon,
rectum and anus.
Caecum- blind ended pouch found below ileocaecal junction. Covered mostly by peritoneum. Easily
mobilised but has no mesentery. Usually full of GAS and palpable in RIL. At ileocecal junction there’s
a valve which prevents food from backflowing to ileum. Attached posterior-medially is appendix
(lymphoid tissue)
Arterial supply:
-SMA->ileocolic artery - > 1. Anterior and posterior caecal arteries. Appendix by 2. appendicular
artery.
Ascending colon- ceacum to R lobe of liver- turns at hepatic flexure to become TC. Retroperitoneal
in its entire length.
Transverse- largest bit of the colon, suspedended by transverse mesocolon. Due to variable length it
can drape down the small intestines. Extends across abdomen and continuous with descending
colon at splenic flexure (connected to diaphragm via phrenocolic ligament)
Descending colon: splenic flexure to pelvic brim, continuous with sigmoid colon. Descending colon is
like ascending, retroperitoneal. Lateral to ascending and descending colon are paracolic gutterspermit free movement of pus or fluid from one part of peritoneal cavity to another.
Sigmoid colon: S shapd, suspected in RIL by sigmoid mesocolon and permid great mobility. Taenia
coli present throught length and their termination marks end of sigmoid- rectosigmoid junction.
Arterial supply:
Branches of SMA and IMA. Dual supply- embryological midgut and hindgut, just proximal to splenic
flexure.
The ascending and proximal two thirds of the transverse colon are supplied by branches from the
superior mesenteric artery:
• Colic branch of the ileocolic artery;
• Right colic artery;
• Middle colic artery.
The distal one third of the transverse, descending and sigmoid colon are supplied by branches from
the inferior mesenteric artery:
• Left colic artery (ascending and descending branches);
• Sigmoid arteries.
Running along the concave margin of the colon is the marginal artery. This artery is usually formed
from the ileocolic, right colic, middle colic, left colic, sigmoidal and superior rectal arteries.
This anastomotic network of arteries can provide an important collateral circulation.
Coeliac trunk- short artery originates from anterior surface of the aorta at the lower border of T12.
Divides into 3 branches- left gastric, splenic and common hepatic arteries.
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The left gastric artery ascends to the cardioesophageal junction where it gives off
oesophageal branches before running along the lesser curvature of the stomach. It gives
branches that supply the anterior and posterior surface of the stomach and anastomoses
with the right gastric artery.
• The splenic artery takes a tortuous path along the superior border of the pancreas towards the
spleen. As it passes posterior to the stomach it gives off the dorsal and greater pancreatic arteries
that supply the neck, body and tail of the pancreas.
Near the hilum of the spleen it gives off short gastric arteries that supply the fundus of the stomach
and the left gastro-omental artery that runs along the greater curvature.
As it enters the hilum it runs in the splenorenal ligament.
• The common hepatic artery passes to the right and divides into two terminal branches, the
gastroduodenal artery and hepatic artery proper.
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The gastroduodenal artery descends towards the superior part of the duodenum and gives
rise to the supraduodenal artery. It then runs posterior to the duodenum and divides into
the superior pancreaticoduodenal and right gastro-omental arteries. The right gastroomental runs alongside the greater curvature to anastomose with the left gastroomental
artery. The superior pancreaticoduodenal artery divides into anterior and posterior
branches that supply the duodenum and head of the pancreas.
The hepatic artery proper passes towards to the liver and gives off the small right gastric
artery that runs along the lesser curvature to join the left gastric artery. The hepatic artery
proper then passes through the hepatoduodenal ligament as part of the portal triad lying to
the left of the bile duct and anterior to the hepatic portalvein. At the porta hepatis it splits
into the left and right hepatic arteries that supply the left and right functional lobes of the
liver, respectively. The cystic artery is usually a branch off the right hepatic artery that
supplies the gall bladder.
SMA- originates from the anterior surface of the aorta at the upper border of L1 vertebra. It gives
rise to the inferior pancreaticoduodenal, jejunal, ileal, ileocolic, right colic and middle colic
arteries.
• The inferior pancreaticoduodenal artery is the first branch that ascends to supply the duodenum
and head of the pancreas. It divides into anterior and posterior branches that anastomose with the
equivalent branches from the superior pancreaticoduodenal artery.
• Coming from the left side of the superior mesenteric artery are the jejunal and ileal branches.
These branches run within the mesentery and bifurcate to form a series of arterial loops – arcades –
by joining with adjacent branches. These arcades run along the mesenteric border of the jejunum
and ileum.
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Emerging from the arcades are narrow straight arteries – vasa recta – that supply the
jejunum and ileum.
• Emerging from the right side of the superior mesenteric artery is the ileocolic artery, which gives
off the appendicular artery to supply the appendix, and the right colic artery. These arteries pass
along the posterior abdominal wall deep to the peritoneum and approach the caecum and ascending
colon from the medial aspect.
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The middle colic artery ascends from the superior mesenteric artery to run within the
transverse mesocolon and supplies the proximal two thirds of the transverse colon.