Unit 18

GI Tract and Vessels

Quiz

Patient Symptoms

• Fifty year old male, smoker, obese– Deep burning retrosternal pain– Reflux of gastric contents (heartburn)– Patient has to sit up to get a good

night’s sleep– Patient responds temporarily to antacids

The Abdominal Aorta begins at the aortic hiatus of the diaphragm (T12) and divides into Common Iliac

arteries at L4

Major branches to the GI tract are:Celiac Trunk - T12Superior Mesenteric - L1Inferior Mesenteric - L3

C

S

I

Celiac Trunk and Branches

After dissecting away the

lesser omentum, clean and

identify the branches of the Celiac

Trunk:

Left GastricCommon Hepatic

Splenic

You may have to reflect the upper border

of the pancreas

downward; watch for

nerve plexuses

Plate 300

Left Gastric

Common Hepatic

Splenic

C

Celiac Trunk

Foregut derivatives are supplied by the

celiac trunk

Expose the terminal

branches of the

Common Hepatic Artery:

Gastroduodenal

Hepatic Artery Proper

Plate 300

Left Gastric

Common Hepatic

Splenic

CHepatic Artery

Proper

Gastroduodenal Artery

The Right Gastric

Artery is usually a branch of

the Hepatic Artery Proper

Plate 300

Left Gastric

Common Hepatic

Splenic

CHepatic Artery

Proper

Gastroduodenal Artery

Right Gastric Artery

The Right and Left Gastric arteries form a strong anastomosis

The Right Gastroomental

artery (Gastroepiploic) is a branch of the Gastroduodenal Artery - it runs in

the greater omentum

Plate 300

Rt. Gastrooment

al Artery

Gastroduodenal Artery

Splenic Artery

Stomach up

At the hilum of the spleen, identify the

Splenic Artery and its

branches:

Left Gastroomental

ArteryShort Gastric

Arteries

Pancreatic Arteries

Plate 291 (old)

Short Gastric Arteries in the Gastrosplenic

LigamentSplenic Artery

running across the

floor posterior to the

omental bursa

Left Gastroomental Artery

Pancreatic Branches

Also identify the Splenic Vein

Plate 300

Rt. Gastrooment

al Artery

Gastroduodenal Artery Left

Gastroomental Artery

Splenic Artery

*The right gastroomental artery has enough branches to take care of the whole stomach e.g., in an esophageal

resection

The Right and Left Gastroomental arteries form a strong anastomosis

Keep in mind that there are many variations in the arteries of this

region!

Remove some of the peritoneum from the right side of the mesentery of

the small intestine.

Superior Mesenteric Vessels

Notice how the

Superior Mesenteric

vessels pass

between the Neck and Uncinate Process of

the pancreas to

enter the mesentery of the small

bowel

Plate 298

Body

Uncinate Process

Neck

Tail

Head

Superior Mesenteric Vessels Attachment of

mesentery of small intestine

Superior Mesenteric Artery

L1

Clean and identify

some of the 18 or more Jejunal and

Ileal branches of

the Superior

Mesenteric Artery and

Vein

Plate 306

Jejunal branche

s

Ileal branche

s

Superior Mesenteric Artery

Superior Mesenteric Artery

They ramify within the

mesentery of the small intestine

Supplies viscera derived embryologically from

midgut

Jejunal branche

s

Ileal branche

s

Plate 306 Superior Mesenteric Artery

Now identify the

following branches that come

off the SMA to the right:

IleocolicAppendicularRight Colic

Middle Colic

Appendicular Artery

Right Colic Artery

Ileocolic Artery

Middle Colic Artery Cut

Incise the anti-mesenteric border (free) of a portion of

jejunum and ileum to study the mucosal lining. Also, look for differences in the branching

patterns of the arteries.

Differences between jejunum

and ileum include:

jejunum is often empty; circular folds are more

prominent; fewer arterial

anastomotic loops in the

mesentery; areas of fat-free

mesentery near mesenteric border

Plate 280A Jejunum

Anastomotic loop (arcades)

Straight Arteries

Circular Folds

Fat-free window

These differences are more

apparent in the living

person

Barium Radiograph

Jejunum means empty

Ileum:Lymphoid Nodules;

fewer circular folds;

more numerous, shorter and

complex arterial

anastomotic loops; no fat-

free mesenteric

border

Plate 280B Ileum

Anastomotic loops

(arcades)

Lymphoid Nodule

Fat

Circular Folds

Shorter Straight Arteries

Note also the complete inner circular and outer

longitudinal muscle layers

C

L

Barium Radiograph

Ileum means

rolled up or twisted

Gastric Folds or Rugae

Plate 276 Stomach

Incise the stomach along its greater

curvature and check

out the gastric

folds. Carry the incision

down through the

pyloric sphincter

region into the first part

of the duodenum, called the duodenal bulb or

ampulla.

Bulb/Ampulla

The duodenal bulb or ampulla is the area

where 80% of peptic ulcers occur - 65% of

ulcers in the duodenum are in the posterior wall.

These ulcers are usually (90%)

associated with the presence of

Helicobacter pylori infection. Folks with

severe chronic anxiety are most prone to the development of peptic ulcers (high acidity – 15X higher – leaves

mucosa vulnerable to H. pylori).

Bulb/Ampulla

Plate 279

Moore, page 257

Treat with antacids and antibiotics

Ampulla

Notice what artery is behind

the posterior wall of the duodenal

ampulla - can be eroded in a perforating peptic ulcer

Plate 279

Gastroduodenal Artery

Common Hepatic Artery

Duodenum

The Splenic Artery can

also be eroded

An acute duodenal ulcer is seen in two views on upper endoscopy.

DD

Pylorus

Radiograph of the pyloric region and duodenal ampulla following a barium

meal Peristaltic wave

Inferior Mesenteric Vessels

Clean and identify the

Inferior Mesenteric Artery and identify the following branches:

Left ColicSigmoid (4)

Superior Rectal

Supplies viscera derived

embryologically from hindgut

Plate 307

Sigmoid Arteries

in sigmoid mesocolon

Left Colic

Superior Rectal Artery

Inferior Mesenteric Artery

Inferior Mesenteric

Artery

L3

Identify the

Marginal Artery and

review the

Middle Colic

Artery

Middle Colic in transverse mesocolon

Marginal Artery

(of Drummond)

Plate 307 Marginal Artery

IMA

The Marginal Artery

represents an anastomosis between the

SMA and IMA; if the aorta is

blocked, this anastomosis as well as others

will compensate

Plate 309

The Portal Vein collects blood from the GI tract and delivers it to the liver for metabolism

of nutrients

Portal Vein

Splenic Vein

Inf. Mesenteric Vein

Sup. Mesenteric Vein

Portal Vein

IVC

Pancreas

Stomach Cut

Identify the veins that make up the Portal Vein posterior to the neck of the pancreas:

Superior Mesenteric Vein

Splenic Vein

Inferior Mesenteric Vein

Plate 290To IVC

Blood from GI tract

Portal Vein

Hepatic Vein

Common Hepatic Duct

Hepatic Artery Proper

Portal Vein

Sinusoids

Portal-Systemic (Caval) Anastomoses

When portal circulation through the liver is diminished or obstructed because of liver

disease or other problems (alcoholism, cancer and hepatitis), blood from the GI tract can still reach the right side of the

heart via the Inferior Vena Cava (systemic) by collateral routes. The blood flow

reverses direction from portal circulation into the SYSTEMIC VEINS

because the portal veins have no valves. Portal hypertension from obstruction of the Portal Vein (e.g., liver cirrhosis) causes an enlargement of anastomotic sites between

the portal and systemic veins which can become varicose possibly resulting in

hemorrhage. These are problematic areas.See handout Unit 19, Moore page 305-308

1. Esophageal varices:

Esophageal Veins: Azygos (Systemic)

Left Gastric Vein: Portal

3. Rectal hemorrhoidsInferior Rectal Vein:

SystemicSuperior Rectal Vein: Portal

2. Paraumbilical veins forming

caput medusaeEpigastric Veins:

SystemicParaumbilical Veins:

Portal

Plate 312 Portal-Systemic Anastomoses

Esophageal varices can

be fatal

Seen here is "caput medusae" which consists of dilated veins seen on the

abdomen of a patient with cirrhosis of the liver.

Also note “Ascites”

Here is a varix near the gastroesophageal junction that is dark red/ black because it has been bleeding. (The

esophagus has been turned inside out.) Endoscopic views of esophageal varices are shown to the right, with dilated veins

bulging into the lower esophageal lumen.

varices

Varices of gut, butt, and caput…….

Cut along the right side of the cecum to expose the Ileocecal

orifice/valve and the opening of

the appendix

Plate 282

The valve may help in

preventing reflux into ileum but isn’t much of

a sphincter

Ileocecal Valve

Ileocecal Orifice and

Valve

Opening of Appendix

Ileum

Mesentery of Appendix

Identify the features of the Colon:

HaustraOmental Appendages

Teniae ColiLarge diameter

Free the ascending and

descending colons from the paracolic

gutters

Plate 271

Haustra (sacculations

)

Omental Appendage

Teniae Coli (3 bands)

Colon

Location of the Appendix - 64%

retrocecal

Inflammation of the appendix is appendicitis. If the appendix ruptures, peritonitis results and an appendectomy is

required.

Moore, Page 273-275

3. With a late stage

appendicitis, pain is felt over

McBurney’s point and there is

rebound tenderness.

1. Initially, pain is felt near the umbilicus (T10)

with appendicitis

2. This is “referred

pain” p. 275

Plate 283 Appendicitis

Quiz

Patient Symptoms

A 32 year old accountant complained of a burning pain in the “pit of her stomach” of ~2 weeks duration. She was a smoker and used NSAID a lot. The pain usually began about two hours after she had eaten and then disappeared when she ate again or drank a glass of milk. Except for mild tenderness in her right upper quadrant, just lateral to the xiphoid process, the PDX results were normal. After tests for H. pylori, radiographs of the upper abdomen, and upper GI studies, a diagnosis of acute peptic ulcer was made.

Laboratory/Quiz