Embryology of the GI tract Flashcards
When in gestation does the gut begin to develop?
4th week
What are the foregut derivatives?
Pharynx to duodenum distal to bile duct Liver Biliary apparatus Pancreas Respiratory system Celiac artery
What are the midgut derivatives?
Duodenum to distal bile duct to right half or 2/3 of the TC SMA
What are the hindgut derivatives?
DIstal to transverse colon to the superior part of the anal canal
- Bladder epithelium
- Urethra
- IMS
Foregut, midgut, or hindgut: liver
Foregut
Foregut, midgut, or hindgut: IMA
Hindgut
Foregut, midgut, or hindgut: SMA
Midgut
Foregut, midgut, or hindgut: biliary appratsu
Foregut
Foregut, midgut, or hindgut: respiratory tract
Foregut
Foregut, midgut, or hindgut: Pancreas
Foregut
Foregut, midgut, or hindgut: celiac artery
Foregut
What is the division in the large intestines from the midgut and the hindgut?
Halfway through to 2/3 through is the midgut. Rest is hindgut
What is the stomodeum? What is it lined with?
Primitive mouth
Ectoderm
What is the gut tube lined with: endoderm, ectoderm, or mesoderm?
Endoderm
What is the end of the primitive gut tube called? What is this lined with?
Proctodeum–lined with ectoderm
What layer of the developing embryo gives rise to most of the musculature of the GI tube?
Mesoderm
What are the muscles that are associated with the mouth derived from?
pharyngeal arches
Foregut, midgut, or hindgut: larynx/trachea
Foregut
What are the folds that separate the trachea from the esophagus in the developing embryo?
tracheoesophageal folds
In the developing GI tube, what is the initial part of the tube that buds off to form the trachea and respiratory system called?
Lung bud
What is the septum that develops between the esophagu and the trachea?
Tracheo-esophageal septum
When in development does the trachea/esophagus form?
4th week
What happens if there is a short esophagus?
Pulls the stomach into the thoracic cavity
What happens to the esophagus lumen as growth continues?
First becomes obliterated by proliferating cells, then subsequently recanualizes
What is an esophageal atresia?
Failure of the esophagus to fully connect
What is most common form of esophageal/tracheal defect?
Atresia of the proximal esophagus, and fistula between the distal part and the trachea
Where do fistula between the trachea and the esophagus usually occur?
Mid to distal esophagus
What are the three mechanisms that bring about esophageal stenosis?
- Stenotic region contains sequestered respiratory tissue elements
- Fibromuscular hypertrophy d/t myenteric plexus damage
- Mucosal diaphragm is present
What layer of the GI tract is the myenteric plexus in?
Between the two layers of the muscularis externa (inner circular layer, outer longitudinal layer)
What is the lusoria artery? What does this cause?
Failure of the Right brachiocephalic trunk to form, leaving the right common carotid branching directly off of the aorta, and an artery coming off of the left side of the trachea to form the right subclavian
May cause obstruction of the trachea
What part of the stomach grows faster:ventral or dorsal side?
Dorsal side
Which way does the GI tract rotate?
Clockwise
Which vagus nerve most anteriorly: the right or left?
Left
What is the acronym for remembering which vagal trunk is anterior and which is posterior??
LARP (left anterior, right posterior)
When does development of the stomach begin?
4th week of development
What is infantile pyloric stenosis?
Marked thickening of the pylorus in the muscularis externa
What is the US landmark that can be seen with infantile pyloric stenosis?
Sonolucent donut