Embryology · USMLE Step 1

USMLE Embryology: Organ System Development

Heart, gut, and urogenital system embryologic development with the classic congenital anomaly tied to each disrupted step.

40 cards · basic cards · AI-written, checked twice. Edit anything.

Study this set free Get FlashKeepers for iPhone
What embryonic mesoderm layer gives rise to the primary heart tube?
Splanchnic (lateral plate) mesoderm
In normal cardiac development, which direction does the heart tube loop?
To the right (dextral looping)
What structures divide the atrioventricular canal into left and right AV orifices?
Endocardial cushions
Failure of endocardial cushion fusion causes what congenital heart defect, common in Down syndrome?
Atrioventricular septal defect
What fetal opening forms where septum primum and septum secundum overlap?
The foramen ovale
What is the most common type of atrial septal defect?
Ostium secundum ASD
What is the single most common congenital heart defect overall?
Membranous ventricular septal defect
What embryonic cell population forms the aorticopulmonary (conotruncal) septum?
Neural crest cells
Failure of the aorticopulmonary septum to spiral properly causes what anomaly?
Transposition of the great vessels
Unequal partitioning of the conotruncal septum, with anterosuperior displacement, causes what four-part anomaly?
Tetralogy of Fallot
Complete failure of the truncus arteriosus to septate results in what anomaly?
Persistent truncus arteriosus
The ductus arteriosus develops from which embryonic aortic arch?
The left 6th aortic arch
Failure of the ductus arteriosus to close after birth causes what anomaly, associated with congenital rubella?
Patent ductus arteriosus
What anatomic landmark marks the boundary between foregut and midgut derivatives?
The major duodenal papilla (in the second part of the duodenum)
At about week 6, the midgut physiologically herniates into what structure?
The umbilical cord (physiologic umbilical herniation)

25 more cards in the app