Embryology Of The Gut Flashcards
Where does the foregut start from and to?
Starts from mouth to the major duodenal papilla (proximal half)
Where does the blood supply of the foregut come from?
Celiac artery
What nerves innervate the foregut?
T5 - T9
Greater splanchnic nerves
What mesenteries does the foregut have?
ventral and dorsal mesenteries
d=greater & v=lesser amenta
Where does the midgut start from & to?
From distal half of duodenum to proximal 2/3 transverse colon
What is the midgut supplied by?
Superior mesenteric artery
What nerves innervate the midgut?
T10 & T11
Lesser splanchnic nerves
What mesenteries does the midgut have?
dorsal mesentery only
Where does the hindgut start from & to?
From 2/3 transverse colon to the anal canal
What is the blood supply to the hindgut?
Inferior mesenteric artery
What is the hindgut innervated by?
T12
Least splanchnic nerve
What mesenteries does the hindgut have?
only dorsal mesentery
What are the components of the foregut?
Mouth, Pharynx, oesophagus, stomach, proximal half of duodenum & the derivative (liver, biliary apparatus & pancreas)
What are the components of the midgut?
Distal half of the duodenum Jejunum Ileum Caecum Appendix Ascending colon Right 2/3 transverse colon
What are the components of the hindgut 7
Left 1/3 transverse colon Decendjng colon Sigmoid colon Rectum Anal canal
What are the layers of the embryo that form the GI tract?
mesoderm and endoderm
What does the mesoderm form?
connective tissue and muscle
what does the endoderm form?
epithelial lining and mucosa
What does the embryo begin to do during the 4th week and what’s it called?
Fold & change shape
Embryonic folding- goes from flat trilaminar disc into a cylinder
Folding occurs in…….
2 planes
What are the 2 planes in embryonic folding?
Horizontal plane
Medial plane
Why does folding occur in two planes?
Due to the differing rates of growth of the embryonic structures
What does folding in the horizontal plane result in?
Two lateral body folds
What does folding in the medial plane result in?
The cranial & caudal folds
How do both planes fold?
Simultaneously
What is the endoderm mainly responsible for?
The development of the GI tract
What happens as embryonic folding continues?
The endoderm moves towards the midline & fuses (incorporating the dorsal Part of the yolk sac) to form the primitive gut tube
What is the primitive gut tube derived from?
Endoderm and visceral mesoderm
What does the endoderm give rise to?
- Epithelial lining of the digestive tract
- Hepatocytes of the liver
- Exocrine and endocrine cells of the pancreas
What 3 distinct parts does the primitive gut tube differentiate into?
The foregut, midgut and hindgut
What happens at the end of the 4th week of development and how does it form the mouth?
The oropharyngeal membrane at the cranial end of the primitive gut tube ruptures to form the mouth
What happens during the 7th week of development and how does it form the anus?
The cloacal membrane at the caudal end of the primitive gut tube ruptures to form the anus
How is the mid/hindgut tube developed?
elongation (growing of tube) herniation (sticking out of abdominal cavity) rotation retraction fixation
Development of the stomach
4th Week=
7th Week=
8th Week=
4th Week= fusiform dilation
7th Week= 90 degree clockwise longitudinal rotation, creates lesser sac
8th Week= ventrodorsal rotation
Development of the stomach
4th Week=
7th Week=
8th Week=
4th Week= fusiform dilation
7th Week= 90 degree clockwise longitudinal rotation, creates lesser sac
8th Week= ventrodorsal rotation
Ventral mesentary=
Dorsal mesentary=
lesser omentum
greater omentum
