Abdomen Lab 5b

Lab 5B - Celiac Trunk and Foregut Vasculature

Lab Overview

Locate and dissect out the celiac trunk, which is the blood supply to the foregut.
Dissect out the 3 branches of the celiac trunk.
Dissect the branches of the 3 branches of the celiac trunk.
Explore the anastomoses of the foregut.

Locating the Celiac Trunk

The arterial supply to the GI tract arises from three unpaired branches of the abdominal aorta. They are:

These branches supply the foregut, midgut, and hindgut respectively.

Use forceps and your fingers to shred the lesser omentum and then dissect down toward the aorta to find the celiac trunk. You’ll be dissecting through the tough celiac plexus of autonomic nerves.

Another approach to finding the celiac trunk is to find the splenic artery coursing through the pancreas and follow it medially to the celiac trunk. Again, feel free to resect portions of the liver to clear the dissection field. See Figure 4.2 and Figure 4.3 for help.

FIGURE 4.1 Abdominal vessels

FIGURE 4.3 Celiac trunk topography

FIGURE 4.2 Branches of the abdominal aorta

To dissect the branches of the celiac trunk, you will dissect the lesser omentum to reveal the arteries (and veins) to the foregut organs. To avoid cutting the vessels, use forceps and your fingers. (Do not use a scalpel). Lift up and hold the liver elevated from the lesser omentum, which will be shredded to reveal the branches of the celiac a. The origin of the celiac trunk from the aorta may be easier to find once the organs that overlie the abdominal aorta are dissected.

Identify the three primary branches of the celiac trunk, along with their successive branches:

Common hepatic a. - branch to the liver
Left gastric a. - branch to the lesser curvature of the stomach
Splenic a. - branch to the spleen

FIGURE 4.4 Branches of the celiac trunk

HELPFUL HINTS

As elsewhere in the body, there is significant variation of the branching pattern of the celiac trunk and associated arteries. Follow arteries out to the organs they supply to definitively name them.

FIGURE 4.5 Branches of the celiac trunk

PUTTING IT ALL TOGETHER

Realize that the celiac trunk is surrounded by nerve fibers of the celiac ganglion, one of the prevertebral ganglia of the sympathetic nervous system. This is the site where preganglionic sympathetic neurons synapse with postganglionic sympathetic neurons. The axons of the postganglionic neurons run with the arteries that supply the foregut, and provide sympathetic innervation to the organs of the foregut.

Dissect through the free border of the lesser omentum to reveal and identify the common hepatic a.; follow it proximally and distally to find the other branches. You may want to dissect all of the vessels in their entirety before identifying them. Identify the following branches:

Common hepatic a. - branch to the liver, gallbladder, stomach, duodenum, and pancreas; gives origin to the proper hepatic, right gastric, and right gastroduodenal aa.
- Hepatic a. proper - dissect the hepatic a. proper, which is superior to the bile duct and lateral to the origin of the right gastric a.; supplies the liver and gallbladder
  - Right gastric a. - courses to the lesser curvature of the stomach on its right-hand side
  - Left and right hepatic aa. - course to the left and right sides of the liver, respectively
  - Cystic a. - a small branch of the right hepatic a. to the gallbladder

Figure 4.7 Common hepatic artery branches of the celiac trunk

HELPFUL HINTS

You will find it easier to clear these vessels and their branches from the surrounding fat, and then trace their branches and put names to them. Use scissor spreading, your fingers, and a probe. If you use a scalpel to dissect this region, you will destroy all of the structures you’re looking for.

- Gastroduodenal a. - free and elevate (do not cut!) the duodenum distal to the pylorus; turn the pyloric end of the stomach to the left, and trace the gastroduodenal a. downward posterior to the first part of the duodenum, where it ends by dividing into two branches:
  - Right gastro-omental a. (aka gastro-epiploic a.) - right side of the greater curvature of the stomach; dissect through the greater omentum to reveal this artery
  - Superior pancreaticoduodenal a. - to dissect the superior pancreaticoduodenal a., lift up the stomach to reveal the duodenum and pancreas; the arteries course along the medial border of the duodenum and pancreas; the pair of terminal branches consists of the anterior and posterior pancreaticoduodenal aa.

Note the common hepatic a. as it branches into the hepatic a. proper and the gastroduodenal a.

Left gastric and splenic a. branches of the celiac trunk

Continue to dissect the celiac trunk to identify the remaining two branches. Use blunt dissection through the related peritoneal ligaments and omenta.

Left gastric a. - branch to the stomach and distal end of the esophagus; follow to the left side of the lesser curvature of the stomach, where the artery anastomoses with the right gastric a.; complete the dissection of both arteries to reveal their anastomosis
- Esophageal a. - attempt to identify an arterial branch from the left gastric a. to the esophagus
Splenic a. - lift up the stomach to dissect the splenic a.; branches to the spleen, pancreas, and stomach; shaped like a corkscrew as it courses over/through/under the pancreas to reach the spleen; courses within the splenorenal ligament
Short gastric aa. - arise from the splenic a., near the hilum of the spleen; supplies the fundus of the stomach
Left gastro-omental a. - arises from the splenic a., near the hilum of the spleen; supplies the greater curvature of stomach; anastomoses with the right gastro-omental a.; complete the dissection of both arteries to reveal their anastomosis

If necessary, trim the greater omentum from the greater curvature of the stomach; leave the gastro-omental vessels attached to the stomach and leave the greater omentum attached to the transverse colon.

HELPFUL HINTS

The left and right gastric aa. form an anastomosis that supplies blood to the lesser curvature of the stomach, while the left and right gastro-omental arteries form an anastomosis that supplies blood to the greater curvature of the stomach.