12. Midgut and Hindgut Flashcards
Which organs make up the midgut? (7)
1/2 of duodenum Jejunum Ileum Caecum Appendix Ascending colon 2/3 of transverse colon
What artery supplies the midgut?
Branches of superior mesenteric artery
At what vertebral level does the superior mesenteric artery branch from the aorta?
L1
Which organs make up the hindgut?
1/3 transverse colon Descending colon Sigmoid colon Rectum Anal canal
What artery supplies the hindgut?
Branches of inferior mesenteric artery
At what vertebral level does the inferior mesenteric artery branch from the aorta?
L3
Where does blood from the jejunum and ileum drain into
Superior mesenteric veins
Which arteries supply the jejunum and ileum?
Jejunal and ileal branches of superior mesenteric artery
Where does lymph from the jejunum and ileum drain?
Mesenteric nodes –>
Pre-aortic nodes at superior mesenteric artery (L1)
What is the nerve supply of the jejunum and ileum?
ANS superior mesenteric plexus
Where does pain from the jejunum and ileum refer?
Umbilical region
Name 3 features of the large intestine that aren’t seen in the small intestine
Haustra (sacculations of wall) Appendices epiploicae (fatty tags) Teniae coli (3 bands of longitudinal muscle)
Which region is the caecum located in?
Right iliac fossa
What is the ileocaecal valve?
Sphincter muscle valve that separates small and large intestine
What is the arterial supply of the caecum?
Caecal arteries form ilieocolic (branch of superior mesenteric)
Where does blood from the caecum drain?
Superior mesenteric vein
Where does lymph from the caecum drain?
Mesenteric then superior mesenteric nodes (at L1)
What is the nerve supply of the caecum?
ANS superior mesenteric plexus
In which region is the vermiform appendix found?
Right iliac
What is McBurney’s point?
Where base of appendix is usually found
1/3rd along line from ASIS to umbilicus
What is the arterial supply of the appendix?
Appendicular artery
Where does blood from the appendix drain?
Posterior caecal vein
Where does lymph from the appendix drain?
Mesenteric then superior mesenteric nodes (at L1)
What is the nerve supply of the appendix?
ANS superior mesenteric plexus
What is the classic description of pain from appendicitis?
Dull pain around umbilicus (T10)
Becomes sharp pain around McBurney’s point
What is the arterial supply of the ascending colon?
Ileocolic and right colic branches of superior mesenteric artery
Where does blood from the ascending colon drain?
Superior mesenteric vein
Where does lymph from the ascending colon drain?
Superior mesenteric nodes at L1
What is the nerve supply of the ascending colon?
ANS from superior mesenteric plexus
What ligament is found at the left colic flexure of the transverse colon?
Phrenicocolic ligament (from diaphragm)
What is the arterial supply of the transverse colon?
Proximal 2/3rds - middle colic artery from superior mesenteric
Distal 1/3 - left colic artery from inferior mesenteric
What is the venous drainage of the transverse colon?
Superior and inferior mesenteric veins
Where does lymph from the transverse colon drain?
Proximal 2/3rd - superior mesenteric nodes at L1
Distal 1/3rd - inferior mesenteric nodes at L3
What is the nerve supply of the transverse colon?
Proximal 2/3rd - Superior mesenteric plexus (from vagus nerve)
Distal 1/3rd - Inferior mesenteric plexus (parasympathetics from pelvis)
What is the marginal artery of colon? Where does it supply?
Anastomoses of inferior mesenteric artery and superior mesenteric artery
Supplies transverse colon
What is the arterial supply of the descending colon?
Left colic and sigmoid arteries
Where does blood from the descending colon drain?
Inferior mesenteric vein
Where does lymph from the descending colon drain?
Inferior mesenteric pre-aortic nodes at L3
What is the nerve supply of the descending colon?
Sympathetic from inferior mesenteric plexus
Parasympathetic from pelvis
What is the arterial supply of the sigmoid colon?
Sigmoid branches of inferior mesenteric artery
What is the venous drainage of the sigmoid colon?
Inferior mesenteric vein
Where does lymph from the sigmoid colon drain?
Inferior mesenteric nodes at aorta (L3)
What is the nerve supply of the sigmoid colon?
ANS from inferior hypogastric plexus
What is the arterial supply of the rectum?
Superior rectal artery from inferior mesenteric
Middle rectal artery from internal iliac
Inferior rectal artery from internal pudendal
What is the venous drainage of the rectum?
Superior - portal system via inferior mesenteric vein
Middle - internal iliac
Inferior - internal pudendal
PORTAL-SYSTEMIC ANASTOMOSIS
Where does lymph from the rectum drain?
Upper - inferior mesenteric nodes (L3)
Lower - internal iliac nodes
What is the nerve supply of the rectum?
Inferior hypogastric plexus
Which veins does the portal vein receive blood from?
Splenic vein Superior mesenteric vein Inferior mesenteric vein Gastric vein Cystic vein
What 3 areas in the abdomen have a dual arterial supply?
Duodenum (foregut to midgut)
Transverse colon (midgut to hindgut)
Rectum (portal-systemic anastomosis)
