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Questions and Answers

Enumerate the derivatives of the gut tube.

Foregut derivatives: Oesophagus, stomach, part of duodenum proximal to the entrance of bile duct. 2. Midgut derivatives: Duodenum distal to the entrance of bile duct, jejunum, ileum, caecum, appendix, ascending colon, proximal 2/3 of transverse colon. 3. Hindgut derivatives: Distal 2/3 of transverse colon, descending colon, sigmoid colon, rectum, and upper part of anal canal.

State the arteries for foregut, midgut, and hindgut derivatives with their origin.

Foregut derivatives: Coeliac trunk (T12). 2. Midgut derivatives: Superior Mesenteric artery (L1). 3. Hindgut derivatives: Inferior Mesenteric artery (L3).

State the blood supply of parts of the oesophagus.

Cervical oesophagus: A: branches from inferior thyroid artery, V: inferior thyroid vein. 2. Thoracic oesophagus: A: branches from thoracic aorta, V: Azygos veins. 3. Abdominal oesophagus: A: branches from left gastric & inferior phrenic artery, V: left gastric vein (tributaries of portal vein).

State 3 main branches of the celiac trunk.

<ol> <li>Left gastric artery. 2. Splenic artery. 3. Common hepatic artery.</li> </ol> Signup and view all the answers

Differentiate between the right and left gastric artery which supply the stomach.

<ol> <li>Left gastric artery: Arises from celiac trunk, supplies lower 1/3 of esophagus and the upper right part of the stomach. 2) Right gastric artery: Arises from hepatic artery, supplies the lower right part of the stomach.</li> </ol> Signup and view all the answers

Differentiate between the right and left gastroepiploic artery which supply the stomach.

<ol> <li>Left gastroepiploic artery: Arises from splenic artery, supplies the stomach along the upper part of the greater curvature. 2. Right gastroepiploic artery: Arises from gastroduodenal branch of hepatic artery, supplies the stomach along the lower part of the greater curvature.</li> </ol> Signup and view all the answers

What artery supplies the fundus of the stomach?

Short gastric arteries, arise from the splenic artery. Signup and view all the answers

State 2 clinical relevance related to the blood supply of the stomach.

<ol> <li>A posterior gastric ulcer can erode the splenic artery. 2. A posterior duodenal ulcer can erode the gastroduodenal artery.</li> </ol> Signup and view all the answers

State the 2 artery supplies of duodenum from foregut and midgut derivatives.

<ol> <li>Foregut derivatives: Superior pancreato-duodenal arteries (anterior and posterior) from the gastroduodenal artery. 2. Midgut derivatives: Inferior pancreato-duodenal arteries (anterior and posterior) from SMA.</li> </ol> Signup and view all the answers

Which parts of the small intestine are involved that develop from the midgut?

Jejunum and Ileum. Signup and view all the answers

State 2 differences between the blood supply of jejunum and ileum.

<ol> <li>Jejunum: Forms 1-2 arcades with long and infrequent branches passing to the intestinal wall. 2. Ileum: Forms 3-4 or more arcades with short and numerous branches passing to the intestinal wall.</li> </ol> Signup and view all the answers

Name 3 arteries that supply the large intestine from midgut and hindgut respectively.

From midgut (SMA): 1. Middle colic artery, 2. Right colic artery, 3. Ileocolic artery. From hindgut (IMA): 1. Left colic artery, 2. Sigmoid branches, 3. Superior rectal artery. Signup and view all the answers

State the blood supply of rectum and upper part of anal canal.

Superior rectal artery, a branch of the Inferior Mesenteric Artery, originating from the abdominal aorta at the level of the 3rd lumbar vertebra. Signup and view all the answers

State the blood supply of the lower part of the anal canal.

<ol> <li>Middle rectal artery (from Internal iliac artery). 2. Inferior rectal artery (from Internal Pudendal artery). 3. Median sacral artery (from abdominal aorta).</li> </ol> Signup and view all the answers

What structures drain into the portal vein?

Blood from the abdominal part of the GIT (except lower part of the anal canal), the spleen, pancreas, and gallbladder. Signup and view all the answers

Describe the formation of the portal vein.

<ol> <li>Formed by the union of splenic vein & SMV behind the neck of the pancreas at L2. 2. Lies in the free edge of the hepatoduodenal ligament. 3. Begins as capillaries in the wall of the gut. 4. Ends by dividing into sinusoids in the liver with capillaries draining into IVC via the hepatic veins.</li> </ol> Signup and view all the answers

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Study Notes

Derivatives of the Gut Tube

Foregut: oesophagus, stomach, and proximal duodenum.
Midgut: distal duodenum, jejunum, ileum, caecum, appendix, ascending colon, and proximal two-thirds of the transverse colon.
Hindgut: distal two-thirds of the transverse colon, descending colon, sigmoid colon, rectum, and upper part of the anal canal.

Arterial Supply by Gut Segment

Foregut: supplied by the coeliac trunk originating at vertebral level T12.
Midgut: supplied by the superior mesenteric artery (SMA) originating at vertebral level L1.
Hindgut: supplied by the inferior mesenteric artery (IMA) originating at vertebral level L3.

Blood Supply of Oesophagus

Cervical oesophagus: supplied by branches from the inferior thyroid artery, drained by the inferior thyroid vein.
Thoracic oesophagus: supplied by branches from the thoracic aorta, drained by the azygos veins.
Abdominal oesophagus: supplied by left gastric and inferior phrenic arteries; drained by the left gastric vein (tributary of the portal vein).

Main Branches of the Celiac Trunk

Left gastric artery.
Splenic artery.
Common hepatic artery.

Comparison of Gastric Arteries

Left gastric artery: branches from the coeliac trunk, supplies lower one-third of the oesophagus and upper right stomach.
Right gastric artery: branches from hepatic artery, supplies lower right part of the stomach.

Comparison of Gastroepiploic Arteries

Left gastroepiploic artery: branches from splenic artery, supplies upper part of the greater curvature of the stomach.
Right gastroepiploic artery: branches from gastroduodenal artery, supplies lower part of the greater curvature of the stomach.

Arteries Supplying the Fundus of the Stomach

Short gastric arteries, which arise from the splenic artery.

Clinical Relevance of Stomach Blood Supply

Posterior gastric ulcers can result in bleeding by eroding the splenic artery.
Posterior duodenal ulcers may erode the gastroduodenal artery, leading to bleeding.

Blood Supply to the Duodenum

Foregut derivatives: supplied by superior pancreato-duodenal arteries (anterior and posterior) from the gastroduodenal artery.
Midgut derivatives: supplied by inferior pancreato-duodenal arteries (anterior and posterior) from the SMA.

Blood Supply of the Small Intestine

Parts supplied by midgut: jejunum and ileum with specific branches: jejunal and ileal branches.

Differences in Blood Supply for Jejunum and Ileum

Jejunum: develops 1-2 arcades with long and infrequent branches.
Ileum: develops 3-4 or more arcades with short and numerous branches.

Blood Supply to the Large Intestine

Midgut supply via SMA: middle colic, right colic, and ileocolic arteries.
Hindgut supply via IMA: left colic, sigmoid branches, and superior rectal artery.

Blood Supply to Rectum and Anal Canal

Rectum and upper anal canal: supplied by the superior rectal artery (branch of IMA).
Lower anal canal: supplied by middle rectal artery (internal iliac artery), inferior rectal artery (internal pudendal artery), and median sacral artery (abdominal aorta).

Venous Drainage of the GIT

Blood from the abdominal GIT (excluding lower anal canal), spleen, pancreas, and gallbladder drains into the portal vein.

Formation of Portal Vein

Formed by the union of the splenic vein and superior mesenteric vein (SMV) behind the neck of the pancreas at L2 level.
Lies along the free edge of the hepatoduodenal ligament.
Begins as capillaries in the gut wall and ends by draining into the liver sinusoids through hepatic veins.