Foregut, Midgut & Hindgut Flashcards
Where does the Oesophagus start and end?
Distal laryngopharynx @C6/7
Ends at cardia of stomach @T11
How long is the Oesophagus?
40cm from incisors to stomach. (Important when inserting tubes)
Describe the right crus of diaphragm
Loop of muscle; forms lower oesophageal sphincter (Not a ‘true’ anatomical sphincter, because it is not a ring of muscle). @T11-12
How does the epithelium change between the lower oesophagus and stomach?
Stratified squamous in oesophagus
Columnar epithelium in stomach
What are mesenteries?
Mesenteries (ventral & dorsal) are double-layered folds of peritoneum attaching the gut tube to the body wall.
Of the foregut, midgut and hindgut, which have dorsal or ventral mesenteries, or both?
Foregut - Dorsal and Ventral
Mid and Hindgut - Dorsal ONLY
Describe the lesser omentum
Peritoneum between the stomach & liver
Composed of 2 Ligaments: Hepatoduodenal and Hepatogastric
Describe the greater omentum
The peritoneum hanging off the greater curvature of stomach
The Hepatoduodenal ligament contains which 3 structures?
Portal Vein
Hepatic Artery
Common Bile Duct
Peritoneal folds develop from…
They differentiate into…
Develop from Dorsal and Ventral mesenteries
Omenta, Mesenteries and Ligaments
Name the omenta of the peritoneal cavity
Greater Omentum (From dorsal mesentery)
Lesser Omentum
(From ventral mesentery)
Name the mesenteries of the peritoneal cavity
Mesentery
(Suspends small bowel)
Transverse Mesocolon
(Suspends transverse colon)
Sigmoid Mesocolon
(Suspends sigmoid colon)
Mesoappendix
(suspends appendix)
Name the ligaments of the peritoneal cavity
Hepatoduodenal
(Part of lesser omentum)
Hepatogastric
(Part of lesser omentum)
Splenorenal & Gastrosplenic Ligs.
(From spleen to kidney / from stomach to spleen)
What level does the coeliac trunk come off at?
T12
What level does the SMA come off at?
L1
What level does the IMA come off at?
L3
What branches off the coeliac trunk?
Common Hepatic, Left Gastric & Splenic arteries
What could damage the gastroduodenal artery?
Peptic Ulcers
Especially posterior to 1st part of duodenum.
Name the retroperitoneal organs
S: suprarenal (adrenal) gland A: aorta/IVC D: duodenum (second and third part) P: pancreas (except tail) U: ureters C: colon (ascending and descending) K: kidneys E: (o)esophagus R: rectum
Name the intraperitoneal organs
S = Stomach A = Appendix L = Liver T = Transverse colon D = duodenum (only the 1st part) S = Small intestines P = Pancreas (only the tail) R = Rectum (only the upper 3rd) S = Sigmoid colon S = Spleen
Describe the duodenum anatomically.
The duodenum is C-shaped and is retroperitoneal (except for the 1st part)
Composed of 4 Parts
What ligament is a useful landmark for the duodeno-jejunal flexure
Ligament of Treitz
Marker point for ‘upper’ vs ‘lower’ GI bleed
Suspends the 4th pt. (ascending part) of the duodenum to the posterior abdominal wall.
Where does the arterial supply for the pancreas and and duodenum come from?
Superior Pancreaticoduodenal artery (from CT)
anastamoses with Inferior Pancreaticoduodenal artery (from SMA).
Where does the caecum sit?
Right Iliac Fossa
What is Teniae Coli?
Longitudinal muscle of colon
Sits in 3 bands that begin at caecum (appendix) and end by covering the rectum
What are the pouches of the large intestine called?
Haustra
What position is the appendix normally in?
Retrocaecal in 60% of people.
What is Intussusception?
Proximal segment of bowel telescopes into an adjacent distal segment
Typically in ileocecal junction
Describe the appendix
Blind ended sac
Has own mesentery and artery (SMA -> Ileocolic a. -> Appendicular a.)
Why is the hepatorenal recess important to consider in a supine patient, with peritonitis?
Infections can spread from under the diaphragm to pelvic cavity and vice versa via Paracolic Gutters.
Describe the arterial supply of the hindgut (route).
IMA -> Left colic, Sigmoidal (Join the Marginal A.)
and Superior Rectal
SMA, IMA and Internal Iliac anastamose (Marginal artery)
Where are the 3 important Portosystemic Anastomoses? What are the clinically significant conditions related to these?
Lower End of the Oesophagus (!Oesophageal Varices)
Lower part of Anal Canal (!Anorectal Varices)
Umbilical Region of Anterior Abdo Wall (!Caput Medusae)
What are Haemorrhoids?
Prolapsed varicosity of internal venous plexus from excessive straining during defecation.
NOT Anorectal Varices!
What positions are Haemorrhoids classically reported on the Anus?
3, 7 and 11 o’clock
Describe what you might see in a barium contract test, if the patient had colon carcinoma?
Apple core sign
Where do GI structures’ lymph drain to?
Thoracic duct and cisterna chyli
