Foregut, Midgut & Hindgut Flashcards
What is the blood supply of the foregut and the vertebral level of the artery origin?
Coeliac trunk - T12
What is the blood supply of the midgut and the vertebral level of the artery origin?
Superior Mesenteric Artery - L1.
What is the blood supply of the hindgut and the vertebral level of the artery origin?
Inferior Mesenteric Artery - L3.
What are the boundaries of the foregut?
From the lower oesophagus to 2nd part of the duodenum (major duodenal papilla).
What are the boundaries of the midgut?
From 2nd part of the duodenum (major duodenal papilla) to 2/3rds of the way across the transverse colon.
What are the boundaries of the hindgut?
From 2/3rds of the way across the transverse colon to the upper anal canal.
Where does the oesophagus begin and end?
Begins at the distal laryngopharynx and ends at the stomach.
What is the approximate vertebral level of the start of the oesophagus?
C6/7.
What proportions of the oesophagus are skeletal and smooth muscle?
Upper 1/3rd is skeletal and lower 2/3rds are smooth.
What is the approximate length from the incisors to the gastro-oesophageal junction?
40cm.
An ultrasound probe can be inserted into the oesophagus to view which chamber of the heart?
Left atrium.
What epithelium lines the oesophagus?
Stratified squamous.
What epithelium lines the stomach?
Simple columnar.
What are the 3 main branches of the coeliac trunk?
- Common hepatic
- Left gastric
- Splenic
What 2 branches does the common hepatic branch of the coeliac trunk split into?
- Proper hepatic
2. Gastroduodenal
Which artery branches off the proper hepatic branch of the coeliac trunk?
Right gastric.
What are the 2 main branches of the gastroduodenal artery?
- Superior pancreaticoduodenal
2. Right gastroepiploic/ Gastro-omental.
Which 2 branches does the left gastric artery of the coeliac trunk split into?
- Left gastric artery
2. Oesophageal branches
What are the 2 branches of the splenic artery of the coeliac trunk?
- Short gastric
2. Left gastroepiploic/ Gastro-omental.
What does the gastroduodenal artery pass behind?
The 1st part of the duodenum.
Given what is passes behind, what could cause damage or a haemorrhage to the gastroduodenal artery?
An ulcer in the first part of the duodenum.
What vertebral levels does the duodenum span?
L1-L3.
What are the other names of the 4 parts of the duodenum?
1 - Superior/bulb
2 - Descending
3 - Horizontal
4 - Ascending
What connects the duodeno-jejunal flexure to the right crus of the diaphragm?
The ligament of Treitz.
What is the ligament of Treitz used as a marker for in terms of GI bleeds?
Used to distinguish between ‘upper’ vs ‘lower’ GI bleeds.
The abdominal peritoneal folds all develop from what?
The original dorsal and ventral mesenteries.
As the abdominal peritoneal folds differentiate they can be called one of what three things?
- Omenta
- Mesenteries
- Ligaments
What are mesenteries?
Double-layered folds of peritoneum attaching the gut tube to the body wall.
Does the foregut have a ventral or dorsal mesentery or both?
Both
Does the midgut have a ventral or dorsal mesentery or both?
Dorsal only.
Does the hindgut have a ventral or dorsal mesentery or both?
Dorsal only.
What is the greater omentum?
The peritoneum hanging off the greater curvature of the stomach.
What is the peritoneum between the stomach and liver called?
The lesser omentum.
What 2 ligaments compose the lesser omentum?
The hepatoduodenal and hepatogastric ligaments.
The free lower edge of the lesser omentum contains what? What are these things collectively knows as?
- Common bile duct
- Hepatic artery
- Portal vein
Collectively known as the portal triad.
Bleeding from the liver can be stemmed by compressing what? What is this manoeuvre called?
The free edge of the lesser omentum. This is called the Pringles manoeuvre.
Between how many metres long is the small intestine?
4-9 metres.
What is another name for the proximal small intestine?
Jejunum
What is another name for the distal small intestine?
Ileum
Is the small intestine intra-peritoneal or retro-peritoneal?
Intra-peritoneal.
What are 4 anatomical differences between the jejunum and ileum?
Jejunum
- Fewer arterial arcades
- Long vasa recta
- Wide lumen
- Thick wall
Ileum
- Many arterial arcades
- Short vasa recta
- Smaller lumen
- Thinner wall
Is the appendix intra-peritoneal or retro-peritoneal?
Intra-peritoneal.
What is the blood supply of the appendix and what is this a branch of?
Appendicular artery of the Ileocolic artery.
What is the band of longitudinal muscle that starts at the appendix and runs superficially along the colon?
Teniae Coli
What are the pouches of the large intestine called?
Haustra
Where does appendicitis pain begin and then spread to? Why is this?
Will begin as visceral pain in the umbilical region as it is a midgut structure, but as it progresses it inflames the nearby parietal peritoneum which is somatically innervated, meaning somatic pain will be felt in the right iliac fossa region.
What is intussusception?
A serious condition in which part of the intestine slides into an adjacent part of the intestine. This telescoping action often blocks food or fluid from passing through. Intussusception also cuts off the blood supply to the part of the intestine that’s affected.
What is a Meckel’s Diverticulum?
A Meckel’s diverticulum, a true congenital diverticulum, is a slight bulge in the small intestine present at birth and a vestigial remnant of the vitelline duct.
Is the ascending colon intra-peritoneal or retro-peritoneal?
Retro-peritoneal.
Is the descending colon intra-peritoneal or retro-peritoneal?
Retro-peritoneal.
Is the transverse colon intra-peritoneal or retro-peritoneal?
Intra-peritoneal.
Is the sigmoid colon intra-peritoneal or retro-peritoneal?
Intra-peritoneal.
What is a sigmoid colon volvulus?
Sigmoid volvulus occurs when the last part of the colon twists on itself, causing obstruction and compromising the blood supply to the colon.
What flexure joins the ascending colon and transverse colon?
Hepatic flexure.
What flexure joins the transverse colon and descending colon?
Splenic flexure.
Is a tumour more likely to cause obstruction in the ascending or descending colon? Why?
Descending colon because the lumen is narrower and the faeces is more solid as more water has been removed from it.
What does an ‘apple core sign’ on imaging of the large intestine imply?
Colorectal adenocarcinoma.
What are paracolic gutters?
Spaces between the colon and abdominal wall.
What is the deepest and superior part of the right paracolic gutter called?
Hepato-renal recess.
In anatomy, what is a watershed area?
Watershed area is the medical term referring to regions of the body that receive dual blood supply from the most distal branches of two large arteries.
Lymph drainage of most abdominal structures travel alongside what? What will it ultimately drain into?
Travels alongside arterial supply and drains into the cisterna chyli and then the thoracic duct.
Where does the portal system drain blood to?
The liver.
Which 2 veins unite to form the portal vein?
Splenic vein and SMV.
Which vein does the IMV join onto?
Splenic vein usually.
If the liver is not draining properly, e.g. due to cirrhosis, which 3 areas are affected? Why these areas?
- Lower end of the Oesophagus
- Lower part of the Anal Canal
- Umbilical region of the Anterior Abdominal Wall
These areas are anastomoses between the portal and systemic system.
What supplies blood to the rectum?
IMA and Internal Iliac artery
How many transverse rectal folds are there and which sides are they on?
2 on left, 1 on right.
The Superior Rectal artery is a branch from what?
The IMA
The Middle and Inferior Rectal arteries branch off from what?
The Internal Iliac artery
If there is a problem with their liver, what sign might a patient get in their rectum that can only be seen on scoping?
Anorectal varices.
What positions relating to a clock are haemorrhoids classically reported to arise at?
3, 7, and 11 O’clock positions.
