Lecture 4 - Embryology I Flashcards
(24 cards)
When does folding occur?
4th week
What lines the gut tube?
Endoderm
What covers the gut tube?
Splanchnic mesoderm
What are the foregut derivatives?
Oesophagus, stomach, pancreas, liver, gallbladder, proximal part of duodenum
What are the midgut derivatives?
Distal part of duodenum, jejunum, ileum, caecum, ascending colon, proximal 2/3 of transverse colon
What are the hindgut derivatives?
Distal 1/3 of transverse colon, descending colon, sigmoid colon, rectum, upper anal canal, internal lining of bladder and urethra
Which structures have dual blood supply and what is their arterial supply?
Duodenum and pancreas
Supplied by coeliac trunk and superior mesenteric artery
What is the peritoneal cavity?
Potential space containing small amount of fluid
What is mesentery?
Double layer of peritoneum suspending gut tube from abdominal wall to allow conduit for blood and nerve supply and allow mobility
How does mesentery form?
Condensation of splanchnic mesoderm
What does dorsal mesentery suspend?
Entire gut tube from dorsal body wall
What does ventral mesentery suspend?
Foregut structures
What are the greater and lesser peritoneal sacs?
Dorsal and ventral mesenteries in foregut region divide the cavity into left and right sacs
Left sac = greater sac
Right sac = lesser sac
Where is the lesser sac?
Behind the stomach
What is omentum?
Specialised region of peritoneum
What is the greater omentum?
Formed from dorsal mesentery
What is the lesser omentum?
Formed from ventral mesentery, from stomach to liver
What influences the position of the greater and lesser sacs?
Rotation of stomach
When are structures retroperitoneal?
When they are not suspended within the abdominal cavity and never had mesentery
When are structures secondarily retroperitoneal?
Began development in peritoneum, had mesentery originally but mesentery becomes lost through fusion at posterior abdominal wall
What is proximal blind-end oesophagus?
Gut tube opens into respiratory tract -> fistula
Which mesentery forms glands in the liver and biliary system?
Ventral
Which mesentery forms glands in the pancreas?
Ventral forms uncinate process and inferior head
Dorsal forms neck down
Which foregut structures are secondarily retroperitoneal?
Duodenum
Pancreas
