Blood supply, lymphatic drainage and nerves of the gastrointestinal system

Dr.khaled omerMB BS Honors - Medicine & Surgery – SIU University SUDAN[MSc] in Human Clinical Anatomy National College- Sudan

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National College for Medical and Technical Studies

Department of Graduate Education [MSc ] in Human Clinical

Anatomy 15/2/2014

, Blood supply lymphatic drai nage and nerves of the Gast

rointestinal system

Presented by Dr KHALID OMER

http://www.oganatomy.org/projanat/gross/33/one.htm



:OBJECTIVESTo define, describe and outlinevertebral level of origin, course and branches of distribution of the celiac trunk, superior mesenteric and inferior mesenteric

pattern of blood supply to the small and large intestines, especially the formation of arcades, and the marginal artery

venous drainage of the various organs of the gastro-intestinal tract and relate this to the embryonic origin.

lymph node groups in the abdomen, and understand which organs they drainvagus and splanchnic nerves; and sacral parasympathetic outflow to the organs of the gastro-intestinal tract.

The abdominal aorta

The abdominal aorta begins at the aortic hiatus of the diaphragm, anterior to the lower border of vertebra TXII.

It descends through the abdomen, anterior to the vertebral bodies, and by the time it ends at the level of vertebra LIV it is slightly to the left of

midline .The terminal branches of the abdominal aorta are the two common iliac arteries.

Anterior branches of the abdominal aorta

The abdominal aorta has anterior, lateral, and posterior branches as it passes through the abdominal cavity.

The three anterior branches supply the gastrointestinal viscera :

the celiac trunk the superior mesenteric and

the inferior mesenteric arteries.

The primitive gut tube can be divided into:

foregut ,midgut, and hindgut regions .

The boundaries of these regions are directly related to the areas of distribution of the three anterior branches of the abdominal aorta.

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Divisions of the gastrointestinal tract into foregut, midgut, and hindgut, summarizing the primary arterial supply to each segment.

The foregut

The foregut begins 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

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 the right two-

thirds of the transverse colon .

The midgut is supplied by the superior mesenteric artery.

The hindgut

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

Celiac trunk The celiac trunk 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

1-left gastric2-spelinc

3-common hepatic arteries

1 .Left gastric artery The left gastric artery is the smallest branch of the celiac

trunk .It ascends to the cardioesophageal junction and sends esophageal branches upward to the abdominal part of the esophagus.

Some of these branches continue through the esophageal hiatus of the diaphragm and anastomose with

esophageal branches from the thoracic aorta .The left gastric artery itself turns to the right and descends along the lesser curvature of the stomach in the lesser omentum.

It supplies both surfaces of the stomach in this area and anastomoses with the right gastric artery .

2 .Splenic artery

The splenic artery, the largest branch of the celiac trunk, takes a tortuous course to the left along the superior border of the pancreas.

It travels in the splenorenal ligament and divides into numerous branches, which enter the hilum of the spleen.

As the splenic artery passes along the superior border of the pancreas, it gives off numerous small branches to supply the neck, body, and tail of the pancreas.

2 .Splenic artery

Approaching the spleen, the splenic artery gives off short gastric arteries, which pass through the gastrosplenic ligament to supply the fundus of the stomach.

It also gives off the left gastro-omental artery, which runs to the right along the greater curvature of the stomach, and anastomoses with the right gastro-omental artery.

Causes of tortusity of the Splenic artery

A-to accommodate for enlargement of the spleen and its movement during respiration

B-to slow the circulation allowing blood to pass in the branches supplying the pancreas

Other tortuous arteries in the body:A-facial B-lingual C- int.carotidD-uterine E-post.inf.cerbellar

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3 .Common hepatic artery

The common hepatic artery is a medium-sized branch of the celiac trunk that runs to the right and divides into its two terminal branches, the hepatic artery proper and the gastroduodenal artery.

The hepatic artery proper ascends towards the liver in the free edge of the lesser omentum .

It runs to the left of the bile duct and anterior to the portal vein, and divides into the right and left hepatic arteries near the porta hepatis.

CONT’D

As the right hepatic artery nears the liver, it gives off the cystic artery to the gallbladder.

The gastroduodenal artery may give off the supraduodenal artery before descending posterior to the superior part of the

duodenum .Reaching the lower border of the superior part of the duodenum, the gastroduodenal artery divides into its terminal branches, the right gastro-omental artery and the superior pancreaticoduodenal artery

The right gastro-omental artery

passes to the left, along the greater curvature of the stomach, eventually anastomosing with the left

gastro-omental artery from the splenic artery .The right gastro-omental artery sends branches to both surfaces of the stomach and additional branches descend into the greater omentum.

The superior pancreaticoduodenal artery divides into anterior and posterior branches as it descends and supplies the head of the pancreas and the duodenum.

These vessels eventually anastomose with anterior and posterior branches of the inferior pancreaticoduodenal artery.

Severance of the Cystic ArteryThe cystic artery must be ligated or clamped and then severed during cholecystectomy, removal of the gallbladder. Sometimes, however, it is accidentally severed before it has been adequately ligated. The surgeon can control the hemorrhage by compressing the hepatic artery as it traverses the hepatoduodenal ligament. The index finger is placed in the omental foramen and the thumb on its anterior wall Alternate compression and release of pressure on the hepatic artery allows the surgeon to identify the bleeding artery and clamp it.

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Superior mesenteric artery

Superior mesenteric artery

The superior mesenteric artery is the anterior branch of the abdominal aorta supplying the midgut.

It arises from the abdominal aorta immediately below the celiac artery,anterior to the lower part of vertebra LI.

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The superior mesenteric artery

is crossed anteriorly by the splenic vein and the neck of pancreas. Posterior to the artery are the left renal vein, the uncinate process of the pancreas, and the inferior

part of the duodenum .After giving off its first branch (the inferior pancreaticoduodenal artery) the superior mesenteric artery gives off jejunal and ileal arteries on its left.

The superior mesenteric artery

Branching from the right side of the main trunk of the superior mesenteric artery are three vessels-the middle colic ,

right colic, and ileocolic arteries-which supply the terminal ileum, cecum, ascending colon, and two-

thirds of the transverse colon .


Inferior pancreaticoduodenal artery

The inferior pancreaticoduodenal artery is the first branch of the superior mesenteric artery .

It divides immediately into anterior and posterior branches, which ascend on the corresponding sides of the head of the pancreas.

Superiorly, these arteries anastomose with anterior and posterior superior pancreaticoduodenal arteries.

This arterial network supplies the head and uncinate process of the pancreas and the duodenum


Jejunal and ileal arteries There may be single and then double arcades in the area of the jejunum, with a continued increase in the number of arcades moving into and through the area of the ileum.

Extending from the terminal arcade are vasa recta (straight arteries), which provide the final direct

vascular supply to the walls of the small intestine .The vasa recta supplying the jejunum are usually long and close together, forming narrow windows visible

in the mesentery .The vasa recta supplying the ileum are generally short and far apart, forming low broad windows.

a.Middle colic artery

The middle colic artery is the first of the three branches from the right side of the main trunk of the superior mesenteric artery.

Arising as the superior mesenteric artery emerges from beneath the pancreas, the middle colic artery enters the transverse mesocolon and divides into right and left

branches .The right branch anastomoses with the right colic artery while the left branch anastomoses with the left colic artery, which is a branch of the inferior mesenteric

artery .

b. Right colic artery

Continuing distally along the main trunk of the superior mesenteric artery, the right colic artery is the second of the three branches from the right side of the main trunk of the superior mesenteric artery.

It is an inconsistent branch, and passes to the right in a retroperitoneal position to supply the ascending colon.

Nearing the colon, it divides into a descending branch, which anastomoses with the ileocolic artery, and an ascending branch, which anastomoses with the middle colic artery.


c. Ileocolic artery

The final branch arising from the right side of the superior mesenteric artery is the ileocolic artery.

This passes downward and to the right towards the right iliac fossa where it divides into superior and inferior branches:

the superior branch passes upward along the ascending colon to anastomose with the right

colic artery ;the inferior branch continues towards the ileocolic junction dividing into colic, cecal, appendicular, and ileal branches.


The specific pattern of distribution and origin of these branches is variable :

the colic branch crosses to the ascending colon and passes upward to supply the first part of the

ascending colon ;anterior and posterior cecal branches, either arising as a common trunk or as separate branches,

supply corresponding sides of the cecum ;the appendicular branch enters the free margin of and supplies the mesoappendix and the

appendix ;the ileal branch passes to the left and ascends to supply the final part of the ileum before anastomosing with the superior mesenteric

artery .


Inferior mesenteric artery The inferior mesenteric artery is the anterior branch of

the abdominal aorta that supplies the hindgut .It is the smallest of the three anterior branches of the abdominal aorta and arises anterior to the body of

vertebra LIII .Initially, the inferior mesenteric artery descends anteriorly to the aorta and then passes to the left as it

continues inferiorly .Its branches include the left colic artery, several

sigmoid arteries, and the superior rectal artery .


Left colic artery

The left colic artery is the first branch of the inferior mesenteric artery.

It ascends retroperitoneally, dividing into ascending and descending branches:

the ascending branch passes anteriorly to the left kidney, then enters the transverse mesocolon, and passes superiorly to supply the upper part of the descending colon and the distal part of the transverse colon, and

anastomoses with branches of the middle colic artery ;the descending branch passes inferiorly, supplying the lower part of the descending colon and anastomoses

with the first sigmoid artery .


Sigmoid arteries

The sigmoid arteries consist of two to four branches, which descend to the left, in the sigmoid mesocolon, to supply the lowest part of the descending colon and the sigmoid colon.

These branches anastomose superiorly with branches from the left colic artery and inferiorly with branches from the superior rectal artery.


Superior rectal artery The terminal branch of the inferior mesenteric artery is the superior rectal artery.

This vessel descends into the pelvic cavity in the sigmoid mesocolon, crossing the left common iliac vessels .

Opposite vertebra SIII, the superior rectal artery divides. The two terminal branches descend on each side of the rectum, dividing into smaller branches in the wall of the

rectum .These smaller branches continue inferiorly to the level of the internal anal sphincter, anastomosing along the way with branches from the middle rectal arteries (from the internal iliac artery) and the inferior rectal arteries (from

the internal pudendal artery) .

:Clinical anatomyThe coelic axis syndrome: This occurs when the coeliac trunk is compressed by the diaphragmatic crura leading to reduced blood supply to the foregut structures. It presents with pain in these structures

Intestinal angina: This may follow atherosclerosis or other narrowing of the mesenteric arteries causing ischaemic pain in the intestines. It is worsened by eating and so victims tend to avoid eating. The impaired absorption and food avoidance lead to wasting of the victims.

Mesenteric artery thrombosis: This is a rare condition that causes gut gangrene

Water shed areas: The areas of the colon where branches of major arteries are vulnerable to ischaemia

Marginal artery – Anastomosis of branches of colic arteries, forming continuous

channel along mesenteric border of large bowel– Enables ligation of inferior mesenteric artery at origin

Importance of marginal artery:•Marginal artery is of significant clinical importance

because it forms an important anastomosis between the superior mesenteric artery and the inferior mesenteric artery. It is sufficiently large to supply the oxygenated blood those parts of large intestine which are supplied by the inferior mesenteric artery. For this reason, the inferior mesenteric artery doesn’t have to be re-implanted into the repaired abdominal aorta in abdominal aortic aneurysm repair.

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The anastomosis of the colic arteries around the concave margin of the large intestine forms a single arterial trunk, known as the marginal artery. It begins at the ileocecal junction, where it anastomoses with the ileal branches of the superior mesenteric artery and ends where it anastomoses with the superior rectal artery.

Superior mesenteric artery (SMA) syndrome is a very rare, life-threatening gastro-vascular disorder characterized by a compression of the third portion of the duodenum by the abdominal aorta (AA) and the overlying superior mesenteric artery. The syndrome is typically caused by an angle of 6°-25° between the AA and the SMA, in comparison to the normal range of 38°-56°, due to a lack of retroperitoneal and visceral fat. In addition, the aortomesenteric distance is 2-8 millimeters, as opposed to the typical 10-20

Venous Drainage of Gastrointestinal Tract


Veins of portal venous systemSystemic veins

Blood from GIT enter the liver via portal vein and leave the liver via hepatic veins to enter the inferior vena cava


Venous drainage of the abdominal part of the gastrointestinal tract, spleen, pancreas and gallbladder except for the inferior part of the rectum, is through the portal system of veins.

Portal Vein It is formed by the union of the splenic vein and the superior mesenteric vein posterior to the neck of the pancreas at the level of vertebra L2.

It is the final common pathway for the transport of venous blood from the spleen, pancreas, gallbladder, and the abdominal part of the gastrointestinal tract.

Ascending towards the liver, the portal vein passes posterior to the superior part of the duodenum and enters the right margin of the lesser omentum. As it passes through this part of the lesser omentum, it is anterior to the omental foramen and posterior to both the bile duct, which is slightly to its right, and the hepatic artery proper, which is slightly to its left

Length : about 8 cm

Portal Vein

It divides into right and left branches, which enter the liver parenchyma.

Tributaries to The Portal Vein

Right and left gastric veins draining the lesser curvature of the stomach and abdominal esophagusCystic veins from the gallbladderThe para-umbilical veins are associated with the obliterated umbilical vein and connect to veins on the anterior abdominal wall.

Splenic Vein

It forms from numerous smaller vessels leaving the hilum of the spleen.

It passes to the right, passing through the splenorenal ligament with the splenic artery and the tail of pancreas.

It crosses the posterior abdominal wall.

Tributaries to The Splenic Vein

Short gastric veins from the fundus and left part of the greater curvature of the stomachLeft gastro-omental vein from the greater curvature of the stomachPancreatic veins draining the body and tail of pancreasInferior mesenteric vein.

Superior Mesenteric Vein

It drains blood from the small intestine, cecum, ascending colon, and transverse colon.

It begins in the RIF as veins draining the terminal ileum, cecum, and appendix.

It ascends in the mesentery to the right of the superior mesenteric

artery .

Tributaries to The Superior Mesenteric Vein

Right gastro-omental vein, draining the right part of the greater curvature of the stomach ;

Anterior and posterior inferior pancreaticoduodenal veinsAnterior superior pancreaticoduodenal vein usually empties into the right gastro-omental vein, and the posterior superior pancreatico duodenal vein usually empties directly into the portal vein.

Inferior Mesenteric Vein

It drains blood from the rectum, sigmoid colon, descending colon, and splenic flexure.

It begins as the superior rectal vein and ascends, receiving tributaries from the sigmoid veins and the left colic vein.

It joins the splenic vein posterior to the body of the pancreas

Sites of portacaval anastomosis

When the portal vein is obstructed or the blood-flow through the liver impeded, the anastomoses between the portal and systemic veins provide alternative routes known as a collateral circulation. The following

are the most important sites of portacaval anastomosis :Lower oesophagus: between the oesophageal tributaries of the left gastric

vein and oesophageal veins joining the azygos system . Anal canal: between the rectal venous plexus (portal drainage and the

middle and inferior rectal veins (systemic drainage) Pelvis: between the rectal venous plexus (portal and systemic drainage) and the other pelvic venous plexuses, such as the vesical and prostatic, the uterine and vaginal (systemic)

Umbilicus: between epigastric veins (systemic) and the left branch of the portal vein, along ligamentum teres .

Bare area of liver: between hepatic venules and veins of diaphragm and thorax .

Intestine and spleen: between colic and splenic venous twigs (portal) and renal or lumbar veins (systemic).

Portosystemic Anastomosis

Lower end of oesophagusUpper part of anal canalUmbilicusRetroperitonealBare area of liver

Clinical Applications

Hemorrhoids at the anorectal junction

Esophageal varices at the gastroesophageal

junction ;Caput medusae at the umbilicus.

Portosystemic Anastomosis

The gastroesophageal junction around the cardia of the stomach-where the left gastric vein and its tributaries form a portosystemic anastomosis with tributaries to the azygos system of veins of the caval system.

The anus-the superior rectal vein of the portal system anastomoses with the middle and inferior rectal

veins of the systemic venous system .The anterior abdominal wall around the umbilicus-the para-umbilical veins anastomose with veins on the anterior abdominal wall.

LYMPHATIC OF THE ABDOMINAL VISCERA

The stomachThe stomach lymph vessels follow the arteries into the left and right gastric nodes, the left and right gastroepiploic nodes, and the short gastric

nodes .All lymph from the stomach eventually passes to the celiac nodes located around the root of the celiac artery.

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The duodenumThe duodenal lymph vessels follow the arteries and drain :

•Upward via pancreaticoduodenal nodes to the gastroduodenal nodes and then to the celiac nodes.

•Downward via pancreaticoduodenal nodes to the superior mesenteric nodes around the origin of the superior mesenteric artery.

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The jejunum and the ileumThe lymph vessels of the jejunum and ileum pass through many intermediate mesenteric nodes and finally reach the superior mesenteric nodes, which are situated around the origin of the superior mesenteric artery.

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The cecumThe lymph vessels of the cecum pass through several mesenteric nodes and finally reach the superior mesenteric nodes.

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The appendix Lymph vessels of the appendix drain into one or

two nodes lying in the mesoappendix and then eventually into the superior mesenteric nodes.

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The ascending colon Lymph vessels of the ascending colon drain into lymph nodes lying along the course of the colic blood vessels and ultimately reach the superior mesenteric nodes.

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Transverse ColonThe proximal two thirds drain into the middle colic nodes and then into the

superior mesenteric nodes; The distal third drains into the colic nodes and then into the inferior mesenteric nodes. 84

Descending ColonThe lymph from the descending colon is drained to the colic lymph nodes and the inferior mesenteric nodes around the origin of the inferior mesenteric artery.

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The efferent vessels pass to the celiac nodes. A few vessels pass from the bare area of the liver through the diaphragm to the posterior mediastinal lymph nodes.

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• Liver• The liver produces

a large amount of lymph—about one third to one half of all body lymph.

• The lymph vessels leave the liver and enter several lymph nodes in the porta hepatis.

•Gall Bladder•The lymph drains into a cystic lymph node situated near the neck of the

gallbladder .•From here, the lymph vessels pass to the hepatic nodes along the course

of the hepatic artery and then to the celiac nodes.87

The pancreatic lymph nodes are situated along the arteries that supply the gland .

The efferent vessels ultimately drain into the celiac and superior mesenteric lymph nodes.

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SpleenThe lymph vessels of the spleen emerge from the hilum and pass through a few lymph nodes along the course of the splenic artery and then drain into the celiac nodes.

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The lymph nodes are closely related to the aorta and form a preaortic and a right and left lateral aortic (Para-aortic or lumbar) chain.

The lymph nodes are closely related to the aorta and form a preaortic and a right and left lateral aortic (Para-aortic or lumbar) chain.

•The preaortic lymph nodes lie around the origins of the celiac, superior & inferior mesenteric arteries.

•They are referred to as the celiac, superior, and inferior mesenteric lymph nodes,

respectively .

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These nodes drain the lymph from the gastrointestinal tract, extending from the lower one third of the esophagus to halfway down the anal canal, and from the spleen, pancreas, gallbladder, and greater part of the

liver .

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The efferent lymph vessels from the preaortic nodes form the large intestinal lymph trunk.

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•The thoracic duct begins in the abdomen as an elongated lymph sac, the

cisterna chyli .•The cisterna

chyli lies just below the diaphragm in front of the first two lumbar vertebrae and on the right side of the aorta.

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The cisterna chyli receives the intestinal trunk, the right and left lumbar trunks, and some small lymph vessels that descend from

the lower part of the thorax.

The cisterna chyli receives the intestinal trunk, the right and left lumbar trunks, and some small lymph vessels that descend from

the lower part of the thorax.95

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lymphatic duct

thoracic duct

left jugular trunk ：converying lymph from the left side of the head and neck

left subclavian trunk ：draining lymph from the left upper limb and part of the thorax on the left side

left bronchomediastinal trunk ： draining lymph from Left thoracic cavity

intestinal trunk, ： draining most of the lymph from the abdominal part of the alimentary canal, liver, pancreas and spleen

left and right 1umbar trunks ： conveying lymph from the lower limbs and the pelvic viscera

left venous angle

thoracic duct

cisterna chyli

• IV. Clinical Considerations• Surgeon may judge extent of metastases from a

malignancy by examining nodes draining the area• For example, from sigmoid colon, first check for

nodes in sigmoid mesocolon, and then examine inferior mesenteric group found at origin of inferior mesenteric artery

Innervation of the GI Tract

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Visceral sensory neuronsMonitor temperature, pain, irritation, chemical changes and stretch in the visceral organsBrain interprets as hunger, fullness, pain, nausea, well-beingReceptors widely scattered – localization poor (e.g. which part is giving you the gas pain?)Visceral sensory fibers run within autonomic nerves, especially vagus and sympathetic nervesSympathetic nerves carry most pain fibers from visceral organs of body trunkSimplified pathway: sensory neurons to spinothalamic tract to thalamus to cerebral cortexVisceral pain is induced by stretching, infection and cramping of internal organs but seldom by cutting (e.g. cutting off a colon polyp) or scraping them

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Referred pain: important to know

Pain in visceral organs is often perceived to be somatic in origin: referred to somatic regions of body that receive innervation from the same spinal cord segments

Plus left shoulder,from spleen

Anterior skin areas to which pain is referred from certain visceral organs

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Visceral sensory and autonomic neurons participate in visceral reflex arcs

•Many are spinal reflexes such as defecation and micturitionreflexes

•Some only involve peripheralneurons: spinal

cord not involved(not shown*)

*e.g. “enteric” nervous system: 3 neuron reflex arcs entirely within the wall of the gut