PROCEDURE
This lab examines the vascular supply, biliary system, and the region of the intestinal tract corresponding to the embryonic foregut (territory supplied by the celiac trunk).
1. On the lateral sides of the lower ribs (both left and
right), cut and reflect any soft tissue superficial to the rib cage exposing the
lower ribs along the mid-axillary line.
(Figure327) (Photo3088)
(Photo3089)
(Photo3090)
2. Using a Stryker saw, working from superior to inferior
cut through all the lower ribs and intercostal soft tissues along the mid
axillary line on both left and right sides.
(Figure327a)
(Photo3091)
(Video3001)
This cuts through the lateral side of the remaining ribs through to 10-11. Palpation is easiest to determine if you are through each of the ribs as you work inferiorly along the mid-axillary line.
Ribs 11 and 12 are floating ribs that do not connect to the costal margin. The end of rib 12 is more posterior than the mid-axillary line and the end of rib 11 extends roughly to the mid-axillary line. (Figure367)
3. Using a Stryker saw, cut through the costal margin at
the xiphoid process such that the transection lines up with the previous midline
abdominal incision.
(Figure327b)
(Photo3092)
(Video3002)
Do not cut soft tissue posterior to the xiphoid process, so as to minimize damage to the diaphragm.
Excessive posterior cutting could result in the diaphragm tearing posteriorly from this point and becoming damaged.
4. Grasp the medial end of the ribs on the right side and
lift the ribcage superiorly and laterally slightly to gently 'stretch' the
diaphragm so you can see where the diaphragm
attaches to the costal margin.
(Photo3041)
It may help to have a second team member or a Belfour retractor to elevate the anterior abdominal wall away from the organs and enhance the viewing angle to where the diaphragm attaches to the inside of the costal margin.
Do not apply excessive force as that can cause the diaphragm to 'split' in the middle. If that does start to happen reduce the amount of stretch force being applied.
If the split is significant, later place a couple of sutures through the split to prevent the tear progressing posteriorly during later lab sessions.
5. Starting at the midline, use scissors to
cut through the diaphragm on the right, staying as close to the ribs as possible,
cutting through the diaphragm to where the falciform ligament is attached to the
liver.
(Figure361) (Photo3042) (Photo3042a) (Video3003)
6. While the second team member elevates the anterior abdominal wall,
using scissors transect the
ligamentum teres hepatis and falciform ligament attachments close to the
anterior abdominal wall.
(Photo3043) (Photo3043a) (Video3004)
7. Use scissors to continue cutting through the diaphragm
attachments to the inside of the costal margin working laterally to the
maxillary line.
(Figure361) (Photo3105) (Photo3105a) (Video3005)
This should result in the diaphragm separated from the
costal margin allowing the panel of right ribcage and attached right anterior
abdominal wall to reflect laterally.
(Photo3094)
(Photo3095)
(Photo3105b)
8. Move to the left side and grasp the medial end of the
ribs to
lift the ribcage superiorly and laterally slightly to gently 'stretch' the
diaphragm so you can see where the diaphragm
attaches to the costal margin.
(Photo3044)
It may help to have a second team member or a Belfour retractor to elevate the anterior abdominal wall away from the organs and enhance the viewing angle to where the diaphragm attaches to the inside of the costal margin.
Do not apply excessive force as that can cause the diaphragm to 'split' in the middle. If that does start to happen reduce the amount of stretch force being applied.
If the split is significant, later place a couple of sutures through the split to prevent the tear progressing posteriorly during later lab sessions.
9. Return to the midline and cut through the diaphragm
along the left side costal margin attachment progressively hinging the left
excised ribcage section laterally.
(Figure361a)
(Photo3044)
(Photo3044a) (Video3006)
This should result in the diaphragm separated from the
costal margin allowing the panel of left ribcage and attached left anterior
abdominal wall to reflect laterally.
(Photo3096)
(Photo3096a)
10. Reflect the left and right sections of ribcage so the ribs are spread to each side.
(Photo3045) (Photo3045b)
11. Identify the stomach in the upper left quadrant
and retract the left liver edge slightly so that you can identify the esophageal
entry to the stomach.
(Figure329) (Netter276)
(Photo3003)
The esophageal entry point to the stomach typically lies just deep to the lateral edge of the left lobe of the liver, although this varies depending on the individual's liver size.
12. Retract the liver superiorly to observe the lesser
omentum connecting along the lesser curvature of the stomach and duodenum
spanning across to the liver.
(Figure329) (Netter276)
(Photo3097)
Lesser omentum - The lesser omentum is a sheet of mesentary connecting stomach/duodenum to the liver. This subdivides into hepatogastric and hepatoduodenal ligament. The largest part is hepatogastric with the smaller right-most edge the hepatoduodenal ligament.
Hepatogastric ligament - A sheet of mesentery, the hepatogastric ligament, spans from the lesser curvature of the stomach to the liver.
Hepatoduodenal ligament - Continuous with the hepatograstric ligament along the right edge is a fold of mesentery connecting the duodenum to the liver. The hepatoduodenal ligament contains the important structures of the common bile duct, the hepatic artery, and the portal vein. These will be dissected in a later session.
13. Insert a finger from the right side posterior to the
hepatoduodenal ligament into the epiploic foramen.
(Figure329) (Netter276)
(Photo3098)
The epiploic foramen is an entry into the lesser sac. The lesser sac is a blind ended region of the peritoneal cavity posterior to the lesser omentum and stomach. Everywhere in the peritoneal cavity except this lesser sac posterior to the stomach is called the greater sac.
14. Insert a rolled up paper towel into the epiploic foramen
such that the hepatoduodenal and hepatogastric ligaments lie on top of the paper
towel.
(Photo3047)
This paper towel will give support during dissection of the hepatic triad structures in the following steps.
15. Using a spreading action of your scissors make an
opening through the anterior side of the hepatoduodenal ligament and remove peritoneum from the anterior surface
to expose the structures within.
(Figure337) (Netter285)
(Photo3099)
The three major structures within the hepatoduodenal ligament are the bile duct (most lateral), hepatic artery proper (medial to the duct) and hepatic portal vein (typically posterior to the artery).
16. With a sharp probe or scissor spreading technique follow
the bile duct superiorly to where it diverges into the cystic duct (heading to the
gallbladder) and common hepatic duct (heading to the liver).
(Figure337) (Netter287)
(Photo3100) (Photo3048)
In patients who have had the gallbladder removed in a cholecystectomy procedure there will no longer be a cystic duct.
The duct is ligated during the surgery and the residual stub of the duct regresses and is rarely present.
17. Follow the common hepatic duct superior to its junction
with the right and left hepatic ducts
(Figure337)
(Netter287)
(Photo3048)
Typically this junction is just prior to entry into the liver proper, however some individuals may have the junction occur inside the liver where you cannot observe it.
18. Return to the proper hepatic artery (medial to
the bile duct) and clean the overlying tissue from the artery.
(Figure337) (Netter290)
(Photo3048)
That tissue is a mix of connective tissue and an autonomic nerve plexus which can both be discarded.
19. Follow the proper hepatic artery superiorly to its
division into the right and left hepatic arteries.
(Figure337)
(Photo3048)
(Photo3004)
Typically the artery junction is prior to entry into the liver proper and inferior to the level where the hepatic duct bifurcated. However some individuals may have the artery branching occur inside the liver where you cannot observe it.
In general there can be considerable variations in vascular patterns in the abdominal region. What is described here and below is the most common branching pattern, but be aware branches may arise from slightly different locations.
Arteries are named by their region of distribution, not by origin or branching pattern. Therefore, regardless of where an artery arises it is named by the target that the vessel supplies.
20. Follow the right hepatic artery to the cystic artery
branch which feeds the gallbladder.
(Netter290)
(Photo3048) (Photo3004)
In patients following gall bladder removal, this artery also regresses and will no longer be present.
21. Identify the portal vein posterior to the bile duct and
hepatic artery.
(Figure337) (Netter296)
If a patient has portal hypertension, not uncommon in the elderly, the portal vein may be significantly enlarged (>13 mm diameter).
22. Follow the portal vein superiorly and observe that it branches
into the left and right portal veins.
(Figure337) (Netter296)
23. Return to the proper hepatic artery and follow it
inferiorly to a junction with the common hepatic artery (which heads medially).
(Figure338) (Netter290)
(Photo3048)
(Photo3004)
If you are particularly careful you will find the right gastric artery arising from the proper hepatic artery. The right gastric artery courses around the lesser curvature of the stomach and anastomoses with the left gastric artery examined below.
The right gastric is quite variable in origin, so you may find it arising from other locations (probabilities are 60% proper hepatic artery, 20% left hepatic artery, 20% gastroduodenal).
Other branches provides blood via branches to the duodenum, pancreas, and to the right gastro-omental (or gastroepiploic) artery. The right gastro-omental artery courses around the greater curvature of the stomach and anastomoses with the left gastro-omental artery examined below.
24. Follow the common hepatic artery medially to where it arises from the celiac trunk
(i.e. where you see other branches).
(Figure338)
(Netter290)
(Photo3049)
(Photo3005)
The celiac trunk itself orients from the aorta pointing directly anteriorly about 1-2cm in length (i.e. it points 'away' from your view). Thus, you won't see the trunk itself, what you will find is the junction where the three celiac trunk branches arise.
These branches are the common hepatic artery you followed, the left gastric artery, and the splenic artery examined below.
The common hepatic artery most typically arises from the celiac trunk, although occasionally it can arise from the superior mesenteric artery.
Around the base of the celiac artery is the celiac ganglia and nerve plexus, this is rarely discernable as a discrete entity. The ganglia looks the same as a lump of connective tissue and is thus not readily discernable.
25. Follow the left gastric artery from the celiac trunk
around to the lesser curvature of the stomach.
(Figure338)
(Netter290)
(Photo3049)
(Photo3005)
The left gastric artery typically exits the trunk superiorly to course from near the esophagus before turning inferiorly along the lesser curvature of the stomach.
The left gastric artery anastomoses with the right gastric artery. Branches arise from both the left and right gastric arteries along their length, these arteries distribute over the anterior and posterior surfaces of the stomach.
If you are particularly careful you may find arising from the left gastric artery a delicate esophageal branch supplying the inferior part of the esophagus.
26. Return to the celiac trunk and follow the splenic
artery to the left where it traverses posterior to the stomach.
(Figure338) (Netter290)
(Photo3049)
(Photo3005)
The splenic artery is typically highly tortuous (almost coiled) in its path across to the spleen.
Along its route you may observe the splenic artery gives off multiple small branches supplying different parts of the pancreas.
27. Locate the spleen in the upper left quadrant by retracting the
stomach as needed to see
the organ.
(Figure338) (Netter290)
(Netter296)
(Photo3101)
The spleen is positioned against the lateral wall deep to ribs 9, 10, and 11. (Netter251)
The position of the spleen and these ribs is clinically important in evaluating whether rib fractures or penetrating injury may have ruptured the spleen. Bleeding from splenic injury is profuse and in severe cases the spleen may need to be completely removed to control the bleeding.
28. Use your
fingers to retract the fundus of the stomach and find the
splenic artery entering the spleen.
(Figure338)
(Netter290)
(Netter291)
(Photo3102)
(Photo3006)
It is common for the splenic artery to start branching into smaller arteries distributing to different parts of the spleen just prior to entering the spleen itself.
Exiting the spleen is the splenic vein, which courses retroperitoneal back to the hepatic portal vein. At this point note the vein, but don't try to follow it back to that junction.
29. Observe the gastro-omental artery coursing along the greater
curvature of the stomach approximately 1 inch from the stomach edge.
(Figure338) (Netter290)
(Photo3102) (Photo3006)
Prior to entering the spleen, the splenic artery gives rise to the left gastro-omental (or gastroepiploic) artery that courses around the greater curvature of the stomach. Small straight branches arise from the gastro-omental artery to connect to the stomach itself.
The left gastro-omental artery will anastomose with the right gastro-omental artery. These give rise to branches supplying blood to the anterior and posterior walls of the stomach.
Also arising from the splenic artery are 5-7 small branches, the short gastric arteries, which supply the fundus of the stomach.
Post-Lab Daily Clinical Review Cases
Each lab has several multiple choice practice cases to reinforce understanding of the material within the lab and associated lectures. These are optional to review at home for consolidating and testing understanding.
CHECKLIST
Soft Structures
Biliary system
Common bile duct
Cystic duct
Common hepatic duct
Right and Left hepatic ducts.
Celiac Trunk
Common hepatic artery
Proper hepatic artery
Right hepatic artery
Cystic artery
Left hepatic artery
Right gastric artery
Left gastric artery
Splenic artery
Gastro-omental
artery
Stomach
Lesser
curvature
Greater curvature
Liver
Right lobe
Left lobe
Epiploic foramen
Spleen