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. How do you differentiate a thyroglossal duct cyst from a persistent cervical sinus?
Excessive resorption of septum primum or secondum (or both)
Cerebral hemisphere - thalami
Dorsal; faulty positioning of genital tubercle
Thyroglossal duct cysts will move with swallowing while persistent cervical sinuses in lateral neck wont

2. What is an example of a syndrome that can cause abnormal neural crest migration and thus CV abnormalities?
All intrinsic muscles of larynx except cricothyroid; CN X (recurrent laryngeal nerve - speaking)
Tunica vaginalis not fully fused
DiGeorge
Neural crest cells

3. To what germ layer does the branchial pouches correlate to?
Endoderm
VSD
No more umbilical circulation emptying into RA
Neuroectoderm

4. What happens in pancreas divisum? what results?
Neuroectoderm
Day 6; maintains corpus luteum; 1st trimester
Ventral and dorsal parts fail to fuse at 8th week; 2 pancreatic ducts!- more prone to pancreatitis
Week 3-8

5. What is the initial step to interventricular septum development? is it complete?
Muscular ventricular septum; no
OCPS and maternal diabetes
Uretopelvis; most common site for obstruction (hydronephrosis) in fetus
Muscles of Mastication: Temporalis - masseter - Lateral and Medila pterygoids - Mylohyoid - anterior belly of the digastric - tensor tympani - tensor veli palatini; ant 2/3 of tongue

6. From what aortic arch does the first part of the maxillary artery arise?
VSD
1st
Mesoderm
Upper 1/3; urogenital sinus

7. From What embryonic layer are the melanocytes from?
3rd and 4th arches
Fetal alcohol syndrome; mental retardation
Ventral bud
Neural crest cells

8. Cleft palate is a failure of fusion of the lateral palatine processes - the nasal septum and or the ________?
Incomplete fusion of paramesonephric ducts; UT abnormalities and infertility
Neural crest development; MEN 2A (pheo - PTH tumor - parafollicular cell tumor)
Mullerian inhibitory factor from Sertoli cells; increased androgen from Leydig cells
Medial palatine processes

9. From What embryonic layer is the eustachian tube from?
Mesoderm
Where the epiblast and hypoblast fuse
Incomplete; yes
Alkylating agents

10. which posterior fossa malformation results in aqueductal stenosis and hydrocephaly? what other spinal cord lesion does this malformation present with?
Mesoderm; epiblast
Arnold chiari; syringomyelia
Surface ectoderm
Lithium

11. What can vit A in excess cause in the fetus?
Lots - cleft palate/lip
2nd; 2nd
3rd pouch
LH

12. What effect does warfarin have on the fetus?
Hemorrhage - bone deformities
After; extrinsic
IMA
Neuroectoderm

13. What connects the thyroid to the tongue? when happens if it doesnt obliterate?
Lots - cleft palate/lip
Thyroglossal duct; persists as pyramidal lobe of thyroid; foramen cecum on tongue is normal remnant of thyroglossal duct
Surface ectoderm
Nicotine; preterm labor

14. What are the two types of posterior fossa malformations? which one results in a hindbrain crowding? and which results in an enlarged posterior fossa? which one is associated with syringomelia?
Neuroectoderm
Arnold Chiari and Dandy Walker; Arnold Chiari; Dandy Walker; Arnold Chiari
Obliterated; forms tunica vaginalis
Valproate acid

15. Where does fertilization occur?
Prevent recurrent UTIs
Ampulla
Neural crest cells
lumbosacral

16. What three components make up the branchial/pharyngeal apparatus?
Grooves/clefts; arches; pouches
Neural crest cells
lumbosacral
Neuroectoderm

17. What is associated with only one umbilical artery?
Persistence of 3rd cleft (groove) and pouch causes fistula between tonsillar area and cleft in lateral neck
is no longer intact
Congenital and chromosomal abnormalities
Maxillary

18. What are the clinical symptoms that present with syringomelia?
Bilateral loss of pain and temperature sensation in upper extremities with preservation of touch sensation
Glans penis and corpus cavernosum and spongiosum; glans clitoris and vestibular bulbs
Hypertrophy of muscularis externis of pylorus; surgical incision
Neuroectoderm

19. Which part of the branchial apparatus makes up membranes?
Lacunae in between the chorionic villi
Ectoderm
All 3
Endocardial cushions

20. Which is more common - epispadias or hypospadias?
Hypospadias
Surface ectoderm
Temporary cervical sinus
pyloric stenosis

21. What produces testis determining factor? what cells are produced from this? and What do they secrete? does this result in?
SRY gene on Y chromosomes; sertoli and leydi; MIF and androgens; suppression of paramesonephric ducts and dev. of mesonephric (all respectively)
Mesoderm
Outgrowth of mesonephric as ureteric bud; most caudal
1st branchial arch

22. In both meningocele and myelomeningocele the dura...
8
Gastric outlet obstruction (bilious vomiting - feeding intolerance - abdominal distention)
is no longer intact
Mesdoerm

23. What is used to keep the PDA open?
Mesoderm
Bulbos Cordis; right ventricle entirely
Prostaglandins
Thyroglossal duct cysts will move with swallowing while persistent cervical sinuses in lateral neck wont

24. From which germlayer does the thyroid develop?? From what structure exactly?
Decidual basalis
Neural plate; closes by week 4
Medial palatine processes
Endoderm - floor of primitive pharynx

25. What do membranous interventricular septal defect cause? What does this lead to?
Midgut; 10th week
Neuroectoderm
3 -4 -6
Initial left to right shunting - then switches

26. What is the prochordal plate?
Muscles of Mastication: Temporalis - masseter - Lateral and Medila pterygoids - Mylohyoid - anterior belly of the digastric - tensor tympani - tensor veli palatini; ant 2/3 of tongue
Where the epiblast and hypoblast fuse
Week 4
V3; VII

27. From What embryonic layer do the ependymal cells arise?
Neural crest cells
Neuroectoderm
Sperm plus egg
Foregut; dorsal mesentery (mesodermal)

28. What is germinal matrix hemorrhage associated with?
Epispadias
Respiratory distress syndrome
Epiblast
Stapedius and hyoid artery

29. What is the notochord? What does the notochord later become?
Mesoderm; nucleous pulposos
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)
Mesoderm
Surface ectoderm

30. what muscles are derived from branchial arch 6? CN?
VSD
All intrinsic muscles of larynx except cricothyroid; CN X (recurrent laryngeal nerve - speaking)
Valproate acid
Aortic arch and prox part of subclavian

31. Which branchial derivative creates the middle ear cavity - eustachian tube and mastoid air cells?
First branchial pouch
Cerebral hemisphere - thalami
Neuroectoderm
Amniotic epithelium

32. What do the 2nd through 4th clefts of the branchial apparatus correlate to?
hypospadias
Uretopelvis; most common site for obstruction (hydronephrosis) in fetus
Temporary cervical sinus
Week 2; bilaminar disk; epiblast and hypoblast

33. What is annular pancreas associated with in infants?
Polyhydramnios - Down syndrome - Esophageal/duodenal atresia - Imperforate anus - Meckel diverticulum
Ventral bud
Mesoderm; epiblast
Neuroectoderm

34. What type of radiation is teratogenic ?
Maxillary and medial nasal processes
Ionizing
Ectoderm - mesoderm - endoderm; epiblast - primitive streak - hypoblast; week 3
VSD

35. What separated myometrium of the uterus from the blastocyst?
Decidual basalis
Persistent connection between amniotic cavity and spinal canal; low folic acid
Foregut; dorsal mesentery (mesodermal)
Bone/cartilage and nerves

36. What is Treacher Collins syndrome? What is the result?
Neuroectoderm
Neuroectoderm
28 week onward
1st arch neural crest fails to migrate --> mandibular hypoplasia - facial abnormalities (cleft palate - decreased slanting of palpebral fissures)

37. what bone/cartilage and nerves are derived from branchial arch 2?
Sonic Hedgehog
Reicherts cartilage: Stapes - Styloid process - Lesser horn of hyloid - Stylohyoid ligament and CN VII
Primitive atrium
Umbilical artery - vein; and whartons jelly (mucus connective tissue) - urachus

38. What are two common findings in pyloric stenosis?
Ventral; failure of urogenital folds to close
Pronephros - mesonephros - metanephros; pronephros; most cranially
Failure of the urachus to obliterate
Palpable olive mass in epigastric region; nonbilious projectile vomitting @around 2 weeks

39. What is the mcc of renovascular hypertension in children? What does this predispose to?
Renal artery stenosis;
Caused by compression on trocheal nerve - causes vertical gaze paralysis (associated with arnold chiari)
Week 10-12; end of 1st trimester
VACTERL; OCPs and maternal diabetes

40. What are the three results of having pathology in the aorticopulmonary septum?
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)
Membrane - all 3 from 1st appartus
Right horn of the SV
Surface ectoderm

41. What is the effect of teratogens before week 3?
All or none
Week 10-12; end of 1st trimester
Right horn of the SV
Week 3; primitive streak formation from the epiblast makes the three layers

42. What hormone is hcG structurally similar too?
Deoxygenated blood; fetal internal iliac arteries to placenta
Endoderm
LH
Hepatic circulation; ligamentum venosum

43. what closes the interventricular foramen?
Physiologic incomplete muscular ventricular septum
VACTERL- vertebral defect - anal atresia - cardiac defects - tracheo - esophageal fistula - renal defects - limb defects
Right horn of the SV
Found in lateral neck; from no obliteration of 2-4th clefts

44. Septum primum (patent foramen oval) caused by excessive resorption of...
Endocardial cushions
Yolk sac; 3rd week
Tunica vaginalis not fully fused
septum primum and/or secundum

45. Does deformation occur during or after the embryonic period? is it due to an extrinsic or intrinsic disruption?
3
After; extrinsic
...
Neuroectoderm

46. What embryological structure gives rise to the trabeculated parts of the left and right ventricle?
First branchial pouch
Mullerian inhibitory factor from Sertoli cells; increased androgen from Leydig cells
Primitive ventricle
Week 3-8

47. What does DHT turn the labioscrotal swelling into? estrogen?
Indomethacin; blocks PG production
Lithium; valve leaflets attach to domain down low in RV- 'atrialized RV'
Polyhydramnios - Down syndrome - Esophageal/duodenal atresia - Imperforate anus - Meckel diverticulum
Scrotum; labia majora

48. As a horseshoe kidney ascends during kidney development - What do they get trapped under?
From the the lung; blood from SVC that went into RV gets shunted from pulm artery to aorta; ligamentum arteriosum
Primitive ventricle
IMA
Surface ectoderm

49. The spleen is ____________ in origin and supplied by a foregut artery
Mesdoerm
Thickened ectoderm at end of each developing limb
Ring of pancreatic tissue can cause duodenal narrowing; ventral pancreatic bud abnormally encircles 2nd part of duodenum
mesodermal

50. Where is the decidua basalis derived from?
Endometrium
From the the lung; blood from SVC that went into RV gets shunted from pulm artery to aorta; ligamentum arteriosum
Temporary cervical sinus
Left horn of the sinus venosus