Development Of The Gut 1 + 2 Flashcards
What does the paraxial mesoderm become?
Somites which develop into:
- skeletal muscle
- vertebra
- cartilage
What does intermediate mesoderm develop into?
Kidneys + gonads
What does the lateral plate of the mesoderm become?
- splanchnic mesoderm > viscera (smooth muscle of gut wall)
- somatic mesoderm > parietal (abdominal wall)
What germlayer of the trilaminar disc develops to form to GI tract?
Endoderm
What are the three parts of the mesoderm?
- paraxial
- intermediate
- lateral plate > splanchnic + somatic
What membranes intially seal the ends of the gut tube during embryonic development?
When do they rupture + what do they form?
- buccopharyneal membrane: 4th week |forms the mouth
- cloacal membrane: 7th week | forms the opening for the anus which completes formation of GI tract
What is the blood supply to the foregut?
Coeliac trunk
What is the blood supply to the midgut?
Superior mesenteric artery
What is the blood supply to the hindgut?
Inferior mesenteric artery
What is the blood supply to the:
- foregut
- midgut
- hindgut
- foregut: coeliac artery
- midgut: superior mesenteric artery
- hindgut: inferior mesenteric artery
What makes up the foregut?
oesophagus > midpoint of 2nd part of duodenum
- oesophagus
- stomach
- pancreas
- liver
- bile ducts
- gall bladder
- midpoint of 2nd part of duodenum
+ lower resp tract
What makes up the midgut?
midpoint of D2 > 2/3 transverse colon
- duodenum
- jejunum
- ilium
- caecum
- ascending colon
- 2/3 transverse colon
What makes up the hindgut?
distal 1/3 transverse colon > upper anal canal
- distal 1/3 transverse colon
- descending colon
- sigmoid colon
- rectum
- upper anal canal
+ cloaca
What is the peritoneal cavity?
The potential space between the parietal and visceral peritoneum
What is the parietal peritoneum derived from?
Somatic mesoderm
parieTal - somaTic
What is the visceral peritoneum derived from?
Splanchnic mesoderm
Describe pain from the parietal peritoneum
Localised
Describe pain from the visceral peritoneum
Vague
Vague | Visceral
Where does the spleen develop embryologically?
Dorsal mesentery
Where does the liver develop embryologically?
Ventral mesentery
liVer - Ventral
List the peritoneal ligaments from anterior to posterior
- falciform ligament: anterior abdominal wall to liver
- lesser omentum: liver to stomach
- gastrosplenic ligament: stomach to spleen
- spleno-renal ligament: spleen to left kidney
What mesenteries do the different parts of the gut have?
- foregut: ventral and dorsal
- midgut: only dorsal
- foregut: only dorsal
What is the foramen of Winslow?
Connection between the greater and lesser sac
What is the falciform ligament between?
Anterior abdominal wall and liver
What is the lesser omentum between?
Liver and stomach
What is the gastro splenic ligament between?
Stomach and spleen
What is the spleno-renal ligament between?
Spleen and left kidney
What are mesenteries?
Double folds of peritoneum that suspend the gut tube from the abdominal wall
What is the greater omentum derived from?
Dorsal mesentery
What is the intraembyronic coelom?
What is its importance?
- the space between the splanchnic and somatic mesoderm
- gives rise to the thoracic and abdominal cavities
- allows for proper positioning + development of the GI and thoracic organs
How are the greater and lesser sacs of the peritoneal cavity formed?
Rotation of the stomach
What are structures not suspended in the peritoneal cavity called?
Retroperitoneal
What does it mean is a structure is secondarily retroperitoneal?
Initially had a mesentery but during development it was lost to fusion with the posterior abdominal wall
What is the role of the endoderm in GI development?
Forms the epithelial lining of most of the GI tract
How does folding contribute to embryonic development?
- sagittal > creates head and tail ends
- lateral > forms ventral body wall + gut tube
What is the vitelline duct?
If it persists beyond birth what can it lead to?
- a connection between the midgut and the yolk sac
- if it persists it an cause developmental abnormalities e.g. Meckel’s diverticulum
What is Meckel’s diverticulum?
What is it caused by?
- a small outpuching of the small intestines
- caused by persistence of the vitelline duct beyond birth
Describe the peritoneum (visceral and parietal)
- derived from the lateral plate mesoderm + Iines the abdominal cavity
- visceral peritoneum: surrounds the viscera
- parietal peritoneum: covers the body walls
- the space in between them is the peritoneal cavity
What abdominal incision would give access to appendix?
Gridiron incision
What structure divides the developing trachea from the developing oesophageus?
Tracheoesophageal septum
Where is the foramen of Winslow?
- The connection between the greater and lesser sac
- Posterior to the free edge of the ventral mesentery (under the portal triad)
What is in the peritoneal cavity?
Small amount of fluid
What are the compartments of the greater sac?
- Supracolic compartment (superior to transverse mesocolon)
- Infracolic compartment (inferior to transverse mesocolon)
