The Gut
The foregutbegins with the abdominal esophagus and ends just inferior to
the major duodenal papilla, midway along the descending part of the
duodenum. It includes the abdominal esophagus, stomach, duodenum
(superior to the major papilla), liver, pancreas, and gallbladder. The spleen
also develops in relation to the foregut region. The foregut is supplied by
the celiac trunk.
The midgut begins just inferior to the major duodenal papilla, in the
descending part of the duodenum, and ends at the junction between the
proximal two-thirds and distal one-third of the transverse colon. It includes
the duodenum (inferior to the major duodenal papilla), jejunum, ileum,
cecum, appendix, ascending colon, and right two-thirds of the transverse
colon. The midgut is supplied by the superior mesenteric artery
The hindgut begins just before the left colic flexure (the junction between
the proximal two-thirds and distal one-third of the transverse colon) and
ends midway through the anal canal. It includes the left one-third of the
transverse colon, descending colon, sigmoid colon, rectum, and upper part
of the anal canal. The hindgut is supplied by the inferior mesenteric artery
3.
Celiac trunk
The celiactrunk is the anterior branch of the
abdominal aorta supplying the foregut. It arises
from the abdominal aorta immediately below the
aortic hiatus of the diaphragm (, anterior to the
upper part of vertebra LI. It immediately divides
into the left gastric, splenic, and common hepatic
arteries.
4.
Celiac trunk
Relations :
A- on each side :
1 Coeliac ganglion and coeliac plexus of autonomic nerves
which surrounds it & sends 2ry plexus around its branches .
2 A crus of the diaphragm.
3 Coeliac group of lymph nodes
B- Anteriorly: Cavity of the lesser sac separating it from the
lesser omentum.
C- Superiorly : Median arcuate ligament of the diaphragm.
D- Inferiorly : Upper border of pancreas .
5.
A- Left gastricartery
Branches of Celiac trunk
It is the smallest branch.
Course : It passes upwards and to the left (behind the lesser sac ) till
it reaches the lower end of the oesophagus, then it descends
downwards along the lesser curvature of the stomach (between the 2
layers of the lesser omentum ) to end by anastomosing with the
right gastric artery about the middle of the lesser curvature.
Branches :
1- Oesophageal branches : to the lower end of the oesophagus. 2-
Gastric branches : to both surfaces of the stomach.
6.
Branches of Celiactrunk
B- Splenic artery
It is the largest branch of the coeliac trunk and is a tortuous artery .
Course and Relations :
- It passes to the left side above the upper border of the pancreas
and
infront of the left kidney where it enters the lieno-renal ligament to
reach the hilum of spleen where it ends by giving 5-6 terminal branches .
-Along its course it lies behind the stomach but separated from it by
the cavity of the lesser sac .
Branches of splenic artery :
1 Pancreatic branches : to the body and tail of the pancreas .
2Short gastric arteries : 5-7 small branches to the fundus of
the stomach through the gastro-splenic ligament.
3 Left gastro-epiploic artery : runs on greater curvature of the
stomach .
4Terminal splenic branches : 5-6 terminal branches which enter
7.
Branches of Celiactrunk
C- hepatic
artery
It is intermediate in size between the splenic and left gastric arteries .
- Course and relations :
-It passes forwards and to the right to reach the upper border of the
1st part of duodenum .
-Then, it curves upwards and ascends in the free border of lesser
omentum (in front of the epiploic foramen) to reach the porta hepatis
The portal vein lies behind it while common bile duct lies to its the right
side.
hepatic branches.
8.
Branches of hepaticartery :
1 Gastro-duodenal artery :
Descends behind the 1st part of the duodenum (in front of
portal vein and medial to common bile duct.
Ends by dividing into : right gastro-epiploic and superior
pancreatico- duodenal artery .
2 Right gastric artery : Passes to the left along the lesser
curvature of the stomach . Ends by anastomosing with the left
gastric artery .
3 Supra-duodenal artery :
- Inconstant small artery (may be absent) which supplies the
upper part of the first part of duodenum .
4Right terminal hepatic branch : enters the right lobe of
the liver.
5 Left terminal hepatic branch : enters the left lobe of the
liver.
6- Cystic artery : passes behind the common hepatic and cystic
ducts to reach the gall bladder . It usually arises from the right
terminal branch .
C- hepatic artery
9.
Superior Mesenteric Artery
Origin: from the front of abdominal aorta opposite the lower border of L1 vertebra ( 1
cm . below the origin of the coeliac trunk )
Course and Relations :
At its origin it lies behind the body of pancreas where the splenic vein lies above it and
the left renal vein lies below it
 Then, it appears at the lower border of the pancreas and runs downwards and to the right
through root of mesentery ( with a curve concave to the right The superior mesenteric vein
lies along the right of the artery and both crosses the following structures in succession :
1 Left renal vein.
2 Uncinate process of pancreas.
3 3rd part of the duodenum.
4 Abdominal aorta.
5 Inferior vena cava.
6 Right genitor-femoral nerve.
Termination : in the right iliac fossa by anastomosing with the ileal branches of the ileocolic
aretry .
10.
Branches of superiormesenteric artery
1 Inferior pancreatico-duodenal artery:
Arises from the superior mesenteric artery as it crosses the uncinate
process of pancreas .
 Ascends between the head of pancreas and the duodenum .
 Ends by anastomosing with the superior pancreatico-duodenal artery
2- Jejunal and ileal branches :
12- 15 branches which arise from the left convex side of the artery . They
pass through the mesentery dividing into branches which anastomose with
each other forming a series of arterial arches , the terminal ones give straight
end arteries ( vasa recta ) which supply
the jejunum and ileum .
3- Ileo-colic artery:
It runs downwards and to the right on posterior abdominal wall giving the
following branches :
1 Ileal branches : to the terminal part of the ileum
2 Anterior caecal branch to the front of caecum
3 Posterior caecal branch to the back of the caecum
4Appendicular branch passes behind the terminal part of the ileum and reaches the appendix through its
mesentery (meso-appendix).
5 Ascending branch to lower 1/3 of ascending colon anastomosing with the descending branch of right colic artery .
11.
4Right colic artery: Arise from the right side of the superior
mesenteric artery a little below middle colic artery
Runs to the right crossing the Rt. psoas major, Rt. ureter and Rt. gonadal
vessels.
Near the ascending colon it divides into 2 branches : ascending and
descending which supply the upper 2/3 of ascending colon and
anastomose with ascending branch of ileo-colic artery and right branch of
middle colic artery .
5 Middle colic artery :
Arises from the superior mesenteric artery just below the pancreas
It enters the transverse mesocolon where it divides into:
1 Right branch anastomosing with ascending branch of right colic
artery.
2 Left branch anastomosing with ascending branch of left colic
artery.
Both branches of the middle colic artery supplies the right 2/3 of
Branches of superior mesenteric artery
12.
Inferior Mesenteric Artery
Origin: from the front of abdominal aorta at the level of 3rd lumbar
vertebra behind the 3rd part of the duodenum and 1.5 inches above the
bifurcation of aorta .
Course and Relations :
1 At the beginning, it lies behind 3rd part of the duodenum
which separates it from the superior mesenteric artery .
2 Then, it descends downwards and to the left behind the peritoneum
of posterior abdominal wall lying in front of :
a.Abdominal aorta.
b. Left sympathetic chain. c. Left psoas major muscle.
3 Inferior mesenteric vein and the left ureter lie to the left side of
the lower part of the artery.
4 Inferior mesenteric artery enters the pelvis by crossing the middle
of
the left common iliac artery, and becomes superior rectal artery .
13.
Branches of inferiormesenteric artery
Branches : (to the left 1/3 of transverse colon , descending colon , sigmoid colon and
rectum ).
1 Left colic artery: runs to the left behind the peritoneum of the posterior
abdominal wall crossing in front of left psoas major, left ureter and left
gonadal vessels.
2Sigmoid arteries : 2-3 arteries : Pass downwards and to the left behind
the peritoneum of post.
abdominal wall crossing in front of Lt. psoas major, Lt. ureter and Lt.
gonadal vessels. The upper one anastomoses with the descending branch of the left
colic artery. The lower one anastomoses with the superior rectal artery. The sigmoid
arteries supply the lower part of the descending colon , and sigmoid colon .
3 Superior rectal artery :
ď‚§ It is the continuation of the inferior mesenteric artery .
It enters the pelvis at the middle of left common iliac artery .
ď‚§ It passes through the medial limb of sigmoid mesocolon then along the
posterior surface of the rectum supplying it and upper 1/2 of anal canal
VENOUS DRAINAGE OFGUT
Portal Circulation
The veins which drain the stomach , small intestine , most of large intestine, spleen, pancreas and gall
bladder end in
the portal vein .
Portal Vein
Origin:
Formed behind the neck of pancreas by union of 2 veins:
a. Splenic vein.
b. Superior mesenteric vein.
Termination:
In the porta hepatis by dividing into 2 branches: right and
left.
Length: 2-3 inches.
16.
Course and Relations:It has 2 parts:
1Retro-duodenal part : Ascends upwards and to the right behind
the 1st part
of the duodenum lying:
 In front of the I.V.C.
 Behind gastro-duodenal artery and common bile duct.
Supra doudenal part :
Ascends in the free margin of lesser omentum having the following
relations:
a. Epiploic foramen: posterior to it.
b.Common bile duct: anterior and to right. c. Hepatic artery:
anterior and to the left.
On reaching the porta hepatic, it divides into 2 terminal branches: a.
Right to right lobe of the liver.
b. Left to left lobe of the liver
2 ligaments attached to left terminal branch of portal vein
1- Ligamentum teres (represents the obliterated umbilical vein of
the
embryo). 2- Ligamentum venosum (represents the obliterated ductus
venosus of the
Portal Vein
17.
Tributaries of portalvein
a. 2 main tributaries
1. Splenic vein.
2. Superior mesenteric vein .
b. 2 veins from the stomach:
1. Right gastric v.
2. Left gastric v.
c. 2 veins drain into its terminal branches :
1 Cystic veins (from gall bladder) drain into right terminal branch.
2Para-umbilical veins (from anterior abdominal wall), run with ligamentum teres
and end into its terminal branch.
18.
Splenic Vein
Begins: bythe union of 5-6 splenic veins at the hilum of the spleen.
Course and Relations :
- The vein passes to the right through the lino-renal ligament, then
across the posterior abdominal wall behind the body of pancreas
and infront of left kidney and abdominal aorta ( below the
splenic artery ).
Ends: behind the neck of pancreas by uniting with the superior
mesenteric vein to form the potal vein.
Tributaries :
1Receives tributaries corresponding to branches of splenic
artery (mention them).
2Inferior mesenteric vein which is a continuation of the
superior rectal vein and recieves tributaries corrosponding to
branches of inferior mesenteric artery.
19.
Superior mesenteric
vein
Begins :at the lower end of root of mesentery .
Course and relations : runs upwards and to the left
along right side of the
superior mesenteric artery ( having the same relations )
Ends : Behind the neck of pancreas by joining the
splenic vein to form portal
vein.
Tributaries : Correspond to branches of superior
mesenteric artery (mention
them + the right gastro-epiploic vein).
20.
Connections between theportal and systemic
veins (Porto-systemic Anastomosis)
1- At the lower end of the oesophagus :
- Oesophageal branches of left gastric vein (portal) with oesophageal branches of azygos vein (systemic)
- In portal hypertension, it leads to oesophageal varices .
2- At the anal canal :
- between superior rectal (portal) and middle and inferior rectal (systemic)
- In portal hypertension, it leads to internal piles.
3- Around the umbilicus :
- Between para-umbilical veins (portal) with superficial veins of the anterior abdominal wall (systemic).
-In portal hypertension, it leads to dilated, radiating veins around the
umbilicus called (caput medusae)
4- Extra-peritoneal : Between right and left colic veins (portal)
and right and left renal veins (systemic)
5- In the bare area of the liver :
- Between twigs from veins of the liver
(portal) and phrenic veins (systemic).
6 Inside the liver itself.
7 The vein of Ritzius : Connects the
superior mesentric vein (portal )
inferior vena cava (systemic ).