Test your basic knowledge |

USMLE Embryo

Instructions:

Answer 50 questions in 15 minutes.
If you are not ready to take this test, you can study here.
Match each statement with the correct term.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.

1. What two things cause VACTERL syndrome?
Neural crest development; MEN 2A (pheo - PTH tumor - parafollicular cell tumor)
During; instrinsic
Primitive ventricle
OCPS and maternal diabetes

2. Where is the apical ectodermal ridge?
Failure to recanalize; 21
Mesoderm
Muscles of facial expression - stapedius - stylohyoid - posterior belly of the digastric
Thickened ectoderm at end of each developing limb

3. From What embryonic layer do the ANS arise?
Mullerian inhibitory factor from Sertoli cells; increased androgen from Leydig cells
4th/5th branchial pouches
Neural crest cells
Neuroectoderm

4. What embryologic structure provides the aorticpulmonary septum?
...
Ovarian ligament and round ligament of uterus; anchors testes within scrotum
Neural crest migration - they then cause spiral
Persistance of herniation of abdominal contents into umbilical cord covered by peritoneum; 13 - 18

5. Which branchial apparatus makes the external auditory meatus?
mesoderm
Neural crest cells
1st cleft/groove (Ectoderm)
Temporary cervical sinus

6. Where is Wnt 7 gene produced?
Annular pancrease
Week 3-8
Apical ectodermal ridge
Surface ectoderm

7. What embryological structure gives rise to the smooth part of the right atrium?
Week 3-8
4th arch; 6th arch
Right horn of the SV
Cytotrophoblast and synctiotrophoblast

8. Name a syndrome cleft palate is often seen in
Mesoderm; nucleous pulposos
Surface ectoderm
DiGeorge
Diencephalon

9. Weeks _______ erythropoiesis takes place in the liver
All 3
VSD
6-30
From teh lung;blood from IVC in RA to LA; fossa ovalis

10. From What embryonic layer does connective tissue and muscle arise?
Epispadias
Mesoderm
Muscles and arteries
4th week

11. what bone/cartilage and nerves are derived from branchial arch 1?
Neuroectoderm
Meckels cartilage: mandible - malleus - INCUS - sphenoMandibular ligament; CN V2 and V3
Cranio - caudal; segmental
First branchial pouch

12. What is another name for the mesonephric duct? paramesonephric?
Vascular accident intra uterine; apple peel atresia
Hepatic circulation; ligamentum venosum
From endocardial cushions (ventral and dorsal meet each other)
Wolffian; mullerian

13. What causes urine discharge from the umbilicus?
Cerebellar tonsillar herniation through foramen magnum
Failure of the urachus to obliterate
20-50yrs - Abdominal pain - Postprandial fullness - Nausea - Peptic ulcers - Pancreatitis - Rarely - biliary obstruction
Pulm art (prox) and ductus arteriosus

14. What artery is derived branchial (aortic) arch 1?
Maxillary
Surface ectoderm
Excessive resorption of septum primum or secondum (or both)
pyloric stenosis

15. What are the three results of having pathology in the aorticopulmonary septum?
Maxillary
Transposition of great vessels (failure to spiral)- right to left shunt; tetralogy of Fallout (right to left shunt caused by skewed development of septum); persistent TA (partial septum development - also right to left shunt)
3 -4 -6
Endocardial cushions

16. What are the aspects of fetal alcohol syndrome?
VACTERL- vertebral defect - anal atresia - cardiac defects - tracheo - esophageal fistula - renal defects - limb defects
Mesoderm
Tunica vaginalis not fully fused
Mental retardation - holoprosencephaly - facial features - fistulas

17. What is the initial step to interventricular septum development? is it complete?
1st
Yolk sac; 3rd week
mesoderm
Muscular ventricular septum; no

18. what chemo drugs can cause neural tube defects in the fetus?
Prosencephalon - mesencephalon - rhombencephalon
Rhombencephalon
Decreases
Folate antagonists

19. Which branchial derivative creates the epithelial lining of the palatine tonsils?
2nd pouch
80%
Apical ectodermal ridge; limb lengthening; stimulates mitosis of underlying mesoderm
Turners; inferior

20. From What embryonic layer does the adenohypophysis arise?
Surface ectoderm
A vitelline fistula - failure of vitelline duct to close
Week 3-8
Epispadias

21. What is the female remnant of processus vaginalis? male remnant?
Prevent recurrent UTIs
Obliterated; forms tunica vaginalis
Dorsal; faulty positioning of genital tubercle
Duodenum to transverse colon; distal transverse colon to rectum

22. What teratogens can cause discolored teeth?
Amniotic cavity and yolk sac
Tetracyclines
Allantois
Gastric outlet obstruction (bilious vomiting - feeding intolerance - abdominal distention)

23. What does the first cleft/groove of the branchial apparatus develop into?
External auditory meatus
Obliterated
Maxillary
not covered

24. What separates the ant 1/3 and post 2/3 of tongue?
Foramen cecum and terminal sulus
Ectoderm - mesoderm - endoderm; epiblast - primitive streak - hypoblast; week 3
Renal artery stenosis;
VACTERL- vertebral defect - anal atresia - cardiac defects - tracheo - esophageal fistula - renal defects - limb defects

25. What components do the mesoderm of the branchial arches give rise to?
Muscles and arteries
Day 6; with implantation
Mullerian inhibitory factor from Sertoli cells; increased androgen from Leydig cells
...

26. What three components make up the branchial/pharyngeal apparatus?
Deformation
From endocardial cushions (ventral and dorsal meet each other)
Grooves/clefts; arches; pouches
Neural crest cells

27. What is the defect in spina bifida occulta? is there any structural herniation? where on the spinal cord is it usually seen?
Apical ectodermal ridge
Epispadias
Failure of bony spinal canal to fuse; no; lower vertebral levels
DES

28. From where did a branchial cleft cyst arise if it found?
Found in lateral neck; from no obliteration of 2-4th clefts
Failure to spiral (aorta coming out of RV and PA coming out of left ventricle)- two completely separate systems
Congenital and chromosomal abnormalities
Mesoderm

29. What is an example of a syndrome that can cause abnormal neural crest migration and thus CV abnormalities?
Rhombencephalon
DiGeorge
Neural crest development; MEN 2A (pheo - PTH tumor - parafollicular cell tumor)
septum primum and/or secundum

30. What causes the degeneration of the spinal cord in syringomelia?
Deoxygenated blood; fetal internal iliac arteries to placenta
Initial left to right shunting - then switches
Fluid filled syrinx causes expansion and degeneration of cord tracts
Prostaglandins

31. what structures are the derivatives of the neural crest cells in branchial arches?
1st branchial arch
Mid gut to yolk sac; omphalomesenteric duct; 7th week
Bone/cartilage and nerves
Neural crest cells

32. From What embryonic layer are the dorsal root and celiac ganglion from?
Bulbos Cordis; right ventricle entirely
Surface ectoderm
They are the edge of neural plate folding; all over the body
Neural crest cells

33. What axis does the basal plate form? what neural system does it become?
Fluid filled cavity in spinal cord; C8- T1; arnold chiari II
StyloPharyngeus
Ventral ; motor
XII

34. From What embryonic layer are the schwann cells from ?
Stapedius and hyoid artery
Mesoderm
Dorsal ventral axis
Neural crest cells

35. what muscles are derived from branchial arch 6? CN?
Palpable olive mass in epigastric region; nonbilious projectile vomitting @around 2 weeks
Fetal alcohol syndrome; mental retardation
1st cleft/groove (Ectoderm)
All intrinsic muscles of larynx except cricothyroid; CN X (recurrent laryngeal nerve - speaking)

36. Which part of pancreas contribute to body? tail? isthmus? accessory pancreatic duct?
Most pharyngeal constrictors - Cricothyroid - levator veli palatini; CN X (superior laryngeal branch - swallowing)
After; extrinsic
Meckels cartilage: mandible - malleus - INCUS - sphenoMandibular ligament; CN V2 and V3
Ventral bud

37. what closes the interventricular foramen?
8
arnold chiari associated with thoraclumbar myelomeningocele
Physiologic incomplete muscular ventricular septum
Umbilical - midgut herniates through umbilical ring; SMA

38. From What embryonic layer does bone arise ?
Primitive ventricle
Endoderm lined structures of ear: middle ear cavity - eustacian tube - mastoid air cells
3rd; proximal part of the internal carotid artery
Mesoderm

39. From What embryonic layer does the neurohypophysis arise?
During; instrinsic
Germinal matrix hemorrhage
Neuroectoderm
Thalidomide; nausea

40. which posterior fossa malformation results in aqueductal stenosis and hydrocephaly? what other spinal cord lesion does this malformation present with?
2; 1
not covered
Arnold chiari; syringomyelia
Wolffian; mullerian

41. From what aortic arch does the common carotid artery arise? what else arises from this arch?
Cytotrophoblast and synctiotrophoblast
3rd; proximal part of the internal carotid artery
Week 2; bilaminar disk; epiblast and hypoblast
Mesencephalon

42. which teratogen can cause Ebsteins anomaly in the fetus?
Week 8
Nutrient and gas exchange
Endoderm
Lithium

43. What does the midgut form? hindgut?
Fetal kidney; fetal swallows - absorbs - and then removed from placental blood
Nutrient and gas exchange
Umbilical artery - vein; and whartons jelly (mucus connective tissue) - urachus
Duodenum to transverse colon; distal transverse colon to rectum

44. From what aortic arch does the stapedial artery arise? the hyoid?
2nd; 2nd
Week 3-8
blood entering the RA
Neural crest cells

45. Which branchial arch derivative is obliterated?
Synctiotrophoblast
5th
Prosencephalon
Mesoderm

46. what drug is used to help close a PDA? what else does this drug treat?
Deoxygenated blood; fetal internal iliac arteries to placenta
Week 10-12; end of 1st trimester
Indomethacin; blocks PG production
Surface ectoderm

47. What teratogens can cause renal damage in the fetus?
arnold chiari associated with thoraclumbar myelomeningocele
ACE inhibitors - HCTZ
Respiratory distress syndrome
Neural crest cells

48. In order to survive tricuspid atresia - What do you need?
VSD
Week 3-8
Synctiotrophoblast
Neuroectoderm

49. What causes a large posterior fossa in a dandy walker malformation? What is found in this fossa?
Primitive atrium
Absent cerebellar vermis; cystic enlargement of 4th ventricle
1st
3rd pouch

50. What is a teratogen that causes Ebsteins anomaly? What is ebsteins anomaly?