Prelab Images - Stomach & Spleen

Prelab Images - Stomach & Spleen

Prelab should consist of reading the lab manual and dissector answers and viewing the dissection video. To begin your study, you may find it useful to look over the Netter's Atlas images listed below.
Step 1. Remove the costal arch from the anterior aspect of the diaphragm. (Play movie)
Plate 268 shows ribs 7-10 overlying the liver. You can saw through ribs 7-10 bilaterally and remove them. This will reveal the diaphragm and more of the structures within the abdominal cavity. Plate 266 shows how the ribs and diaphragm will look after ribs 7-10 are removed.
Step 2. Examine the omental bursa and the derivatives of the dorsal and ventral mesogastria. (Play movie)
The lesser omentum and its hepatogastric and hepatoduodenal ligaments are all labeled in plate 275. The epiploic foramen is labeled in plates 272 and 275. This foramen leads into the omental bursa (lesser sac), which will be explored soon. Plate 269 shows the greater omentum. The part of the greater omentum that attaches to the colon is the gastrocolic ligament and the part that hangs over the small intestines is known as the omental apron. Plate 272 labels the gastrosplenic, splenorenal, and gastrophrenic ligaments, which are all part of the greater omentum. Plates 272 and 273 label the omental bursa (lesser sac). See the learning module for how this sac develops. Plates 348 and 336 also attempt to identify the omental bursa. Plate 263 shows the transverse colon lifted up to expose the transverse mesocolon that you need to cut through in lab. After cutting through the transverse mesocolon you will be able to explore the omental bursa (lesser sac) from below and locate the stomach, spleen, pancreas, and posterior body wall in relation to the lesser bursa (272 and 273).
Step 3. Identify the parts of the stomach and expose the celiac artery. (Play movie)
Plate 275 identifies the stomach and its parts: cardiac part, fundus, body, pyloric antrum, and pylorus. Plate 276 shows the gastric rugae that you can observe on a plastinated specimen. Make a cut through the pylorus on your cadaver so you can observe the pyloric sphincter (labeled pylorus in plates 276 and 277). Plate 275 defines the lesser and greater curvatures of the stomach. Plates 232 and 275 label the abdominal esophagus passing into the stomach. Plates 276 and 277 show the pyloroduodenal junction. After this junction the duodenum will move posteriorly and become retroperitoneal (plate 274). Plate 264 shows the celiac artery branching off of the abdominal aorta. This artery and its branching will be observed in the next step.
Step 4. Expose the branches of the celiac artery and define its branches to the stomach and spleen. (Play movie)
Plate 275 shows the lesser omentum. Cut through the central part of the hepatogastric ligament to avoid damaging any vasculature. This will expose the omental bursa (272). The left gastric artery is identified in plate 300 and the gastropancreatic fold it travels in is labeled in plate 272. Trace this artery along the lesser curvature of the stomach and try to find gastric, esophageal, and possibly hepatic branches (the latter two will move superiorly off the left gastric artery, see plate 300). The course of the accompanying left gastric vein is shown in plates 309 and 312. Plate 319 shows the hepatic branch of the anterior vagal trunk moving through the superior portion of the hepatogastric ligament. Be careful not to damage this while tracing the left gastric nerve. Plate 300 shows the celiac trunk. Try to trace the left gastric nerve back to the celiac trunk. Plate 272 shows the common hepatic artery in the right gastropancreatic fold (labeled peritoneal fold in 272). Trace this artery from the vicinity of the celiac trunk until it divides into the proper hepatic and gastroduodenal arteries. Plate 275 shows the hepatoduodenal ligament, which contains the proper hepatic artery. Plate 300 shows the proper hepatic artery giving off the right gastric artery. Trace the right gastric artery to the lesser curvature of the stomach and see if you can trace it to where it anastomoses with the left gastric artery. Plate 348 shows the celiac trunk behind the posterior body wall peritoneum sending vessels forward to supply structures of the abdominal cavity. Plate 300 also shows the gastroduodenal artery giving off the posterior superior pancreaticoduodenal artery and then branching into the anterior superior pancreaticoduodenal artery and right gastro-omental arteries at the inferior border of the duodenum. Plate 300 also shows the right gastro-omental (gastroepiploic) artery coursing along the greater curvature of the stomach and giving branches to the stomach and greater omentum. Plates 300 and 291 show the relation of the celiac trunk to the pancreas. Plate 291 shows the origin of the splenic artery. Plate 272 shows the splenic artery in the splenorenal ligament as it passes to the spleen. Plate 272 also labels the gastrosplenic ligament. Plates 300 and 291 show the splenic artery giving off branches to the pancreas (will be covered more later), splenic branches, short gastric arteries, and the left gastro-omental artery. Trace each of these vessels. Try to trace the left gastro-omental until it anastomoses with the right gastro-omental artery and find gastric and omental branches. Plate 301 may also be helpful for reviewing some of the previously mentioned arteries.
Step 5. Examine the spleen, its mesenteric relations and the origin of the portal vein. (Play movie)
Plate 300 shows the spleen. Plate 272 reviews the splenorenal and gastrosplenic ligaments. Plate 268 shows the location of the spleen in the abdominal cavity. Plates 300 and 291 show the blood supply to the spleen. The right gastric vein and portal vein are shown in plate 309 and 312. Plate 275 shows the hepatoduodenal ligament and plate 288 shows the common bile duct, portal vein, and proper hepatic artery within the ligament (also see plate 300 for the relation of these structures to each other). Plates 309 and 312 show the left and right gastric vein anastomosing to form the coronary vein.

Plates 314 and 315 show all the groups of lymph nodes listed: nodes around cardia, left gastric, celiac, (supra- and sub-) pyloric, gastro-omental, hepatic, pancreatic, and splenic. Plate 266 also shows lymphatic drainage of the abdominal cavity.
Step 6. Expose the branches of the vagal trunks to liver, stomach, and celiac ganglion. (Play movie)
Plate 240 shows the left vagus nerve forming the anterior vagal trunk and the right vagus nerve forming the posterior vagal trunk. Plate 319 shows the anterior vagal trunk giving off many small gastric branches and a large hepatic branch that travels in the lesser omentum to the liver and then inferiorly towards the duodenum (labeled as towards the pyloric part of stomach in Netter's). The hepatic branch may travel with a hepatic branch of the left gastric artery on its way to the liver. Plate 320 shows the posterior vagal trunk and its many gastric branches. Also find the branch of the posterior vagal trunk to the celiac plexus. Plate 126 shows the entire distribution of the vagus nerve (you will see that it innervates the gastrointestinal tract all the way up to the left colic flexure). Plate 209 shows the formation of the greater splanchnic nerve (T5-T9). Plates 320 and 321 show that this nerve carries presynaptic sympathetic nerve fibers to the celiac plexus where they will synapse. The postsynaptic nerve will then distribute to the stomach. Plate 269 shows the greater omentum and omental apron. Plate 272 shows the ligaments of the greater omentum and plate 275 shows the ligaments of the lesser omentum. Plate 273, 348, and 336 may also be helpful to organize the mesenteries of the stomach.