Dissection-Abdominal viscera .pdf

Abdominal dissection 1 Abdominal wall reflection 1) When the thoracic wall was reflected, cuts were made laterally along the ribs and the proximal portion of the abdominal wall. a) Use your scissors to extend this cut towards the anterior superior iliac spines on each side,...

Abdominal dissection 1 Abdominal wall reflection 1) When the thoracic wall was reflected, cuts were made laterally along the ribs and the proximal portion of the abdominal wall. a) Use your scissors to extend this cut towards the anterior superior iliac spines on each side, stopping just superior to the ASIS. Loosen the abdominal wall from the underlying peritoneum as you go and take care not to cut into the intestine or other organs. b) Reflect the entire anterior thoracoabdominal wall inferiorly to expose the abdominal cavity. As you reflect, you may need to cut the falciform ligament and round ligament of the liver if this has not already been done. Do this as near to the abdominal wall as possible. 15.19 2) Examine the deep surface of the anterior abdominal wall. (See Gilroy, figs. 13.5, 13.15) a) Identify the arcuate line and transversalis fascia. b) Identify the inferior epigastric artery. From what artery does this arise? With what artery does the inferior epigastric artery anastomose? Abdominal viscera 1) Identify features of the peritoneal cavity: parietal and visceral peritoneum, greater omentum, lesser omentum. (See Gilroy, figs. 14.7-14.9) 2) Identify the liver, the stomach, and the gall bladder. You may need to retract the inferior border of the liver to reveal parts of the stomach and/or gall bladder. (See Gilroy, fig. 15.4) a) On the stomach, identify the greater and lesser curvatures, body, fundus, cardia, and pyloris. i) Find the abdominal part of the esophagus entering the stomach at the cardia. ii) Find the proximal portion of the duodenum distal to the pyloris. These are separated by the pyloric sphincter of the stomach which is often palpable as a firm band in the visceral wall, if not readily visible from the external surface. iii) Lift the left side of the stomach to find the spleen. (See Gilroy, fig. 15.8) b) On the liver, identify the right and left lobes, the falciform ligament, and ligamentum teres  (round ligament of the liver). (See Gilroy, fig. 15.19) i) Note the lesser omentum spanning between the lesser curvature of the stomach and the inferior surface of the liver. ii) Use the closed-open technique with your scissors to break through the lesser omentum and expose the portal triad: the bile duct, proper hepatic artery, and portal vein. (See Gilroy, figs. 15.28, 16.19) (1) Clean the bile duct proximally to reveal the cystic duct and hepatic duct. Follow it distally to its terminus in the duodenum. (2) Clean the proper hepatic artery proximally to reveal the common hepatic artery, the right gastric artery, and the gastroduodenal artery. iii) Continue removing any remaining lesser omentum in order to clean the common hepatic artery to its origin on the celiac trunk. This will begin to reveal the pancreas and the remaining branches of the celiac trunk: the left gastric, and splenic arteries. (See Gilroy, fig. 16.20) (1) Follow the splenic artery as it passes posterior to the stomach to the spleen. (2) Clean the remaining portion of the pancreas as you follow the splenic artery, noting that portions of the splenic artery may be embedded in the pancreas. Note the relationship of head of the pancreas to the descending duodenum. 3) Turn the greater omentum superiorly over the stomach. Identify the large and small intestines. (See Gilroy, figs. 15.11-15.14) a) Trace the digestive tract from the stomach to the duodenum, jejunum, ileum, ileocecal junction, cecum, ascending colon, right colic flexure, transverse colon, left colic flexure, descending colon, to sigmoid colon. Do not expect to see the rectum until we dissect the pelvis. i) You do not need to identify or locate exact transitions between the regions of the small intestine. ii) Along the colon, identify the haustra and teniae coli. b) Free the transverse colon from the greater omentum, and remove any portions (transverse mesocolon) that remain attached to the duodenum and pancreas. The greater omentum should now only be attached to the greater curvature of the stomach. c) Push the jejunum and ileum to the right. Identify the mesentery. Palpate the root of the mesentery near the duodenum, feeling for the tube-like superior mesenteric artery and vein travelling within the mesentery. Use the close-open technique with your scissors to open the mesentery and reveal the superior mesenteric artery and vein. (See Gilroy, figs. 16.10, 16.11) i) Clean enough of the mesentery and peritoneum to follow the superior mesenteric artery to the aorta. ii) Attempt to follow the superior mesenteric artery distally as it branches into its intestinal, ileocolic, right colic and middle colic branches to supply the small intestine and proximal half  of the colon. You will need to turn the small intestine from right to left to find these iii) Do not attempt to remove all of the mesentery surrounding the small intestine. 4) Remove the parietal peritoneum from the aorta to reveal the inferior mesenteric artery. Attempt to follow the inferior mesenteric artery distally to find its branches, the left colic artery, sigmoid arteries, and superior rectal artery suppling the distal part of the colon. (See Gilroy, fig. 16.12) 5) Having removed much of the mesentery and peritoneum, return to the veins and attempt to trace the inferior mesenteric vein to the splenic vein. Find the superior mesenteric vein and follow it anterior to the duodenum and posterior to the pancreas where it meets the splenic vein to form the portal vein. (See Gilroy, figs. 16.20, 16.21)