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. From What embryonic layer do CNS neurons arise?
mesoderm
Neuroectoderm
Failure of bony spinal canal to fuse; no; lower vertebral levels
Thyroglossal duct; persists as pyramidal lobe of thyroid; foramen cecum on tongue is normal remnant of thyroglossal duct

2. From What embryonic layer does bone arise ?
Dorsal; faulty positioning of genital tubercle
Fetal and maternal
Mesoderm
Arnold Chiari and Dandy Walker; Arnold Chiari; Dandy Walker; Arnold Chiari

3. What is the mcc of renovascular hypertension in children? What does this predispose to?
Ampulla
Renal artery stenosis;
Thickened ectoderm at end of each developing limb
Membrane - all 3 from 1st appartus

4. What components do the mesoderm of the branchial arches give rise to?
Muscles and arteries
Right common cardinal vein and right anterior cardinal vein
Neural crest cells
septum primum and/or secundum

5. How does annular pancreas present in children?
not covered
Gastric outlet obstruction (bilious vomiting - feeding intolerance - abdominal distention)
Neural crest cells
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 embryonic layer does connective tissue and muscle arise?
Mesoderm
Tunica vaginalis not fully fused
Where the epiblast and hypoblast fuse
Duodenum to transverse colon; distal transverse colon to rectum

7. What does the ductus venosus shunt blood away from? What is its remnant?
Lithium; valve leaflets attach to domain down low in RV- 'atrialized RV'
DHT; estrogen
Thyroglossal duct; persists as pyramidal lobe of thyroid; foramen cecum on tongue is normal remnant of thyroglossal duct
Hepatic circulation; ligamentum venosum

8. From What embryonic layer does the pineal gland arise?
Ring of pancreatic tissue can cause duodenal narrowing; ventral pancreatic bud abnormally encircles 2nd part of duodenum
Week 8
Week 3-8
Neuroectoderm

9. In what chromosomal disorder is horseshoe kidney commonly seen? what poles of the kidneys fuse?
Turners; inferior
1st arch neural crest fails to migrate --> mandibular hypoplasia - facial abnormalities (cleft palate - decreased slanting of palpebral fissures)
Alkylating agents
Mesoderm

10. Weeks _______ erythropoiesis takes place in the liver
Thyroglossal duct; persists as pyramidal lobe of thyroid; foramen cecum on tongue is normal remnant of thyroglossal duct
6-30
Mullerian inhibitory factor from Sertoli cells; increased androgen from Leydig cells
Excessive resorption of septum primum or secondum (or both)

11. What is holoprosencephaly? what eye disorder does it result in?
Myelencephalon
Surface ectoderm
Decreased separation of hemispheres across midline; cyclopia
Fetal and maternal

12. From What embryonic lare are the odontoblasts from?
Neural crest cells
Mesoderm; epiblast
Week 8
Foramen cecum and terminal sulus

13. From where did a branchial cleft cyst arise if it found?
Neural crest cells
Foregut; dorsal mesentery (mesodermal)
Endoderm - floor of primitive pharynx
Found in lateral neck; from no obliteration of 2-4th clefts

14. What does the ureteric bud interact with and What does it induce it to become?
All 3
Metanephric mesenchyme; differentiation and formation of glomerulus and renal tubules to distal convoluted tubule
Neuroectoderm
Incomplete fusion of paramesonephric ducts; UT abnormalities and infertility

15. What causes the degeneration of the spinal cord in syringomelia?
Fluid filled syrinx causes expansion and degeneration of cord tracts
Decreases
...
Skewed development of AP septum

16. Which branchial apparatus derivative makes the tympanic membrane of the ear?
Membrane - all 3 from 1st appartus
From teh lung;blood from IVC in RA to LA; fossa ovalis
Week 2; bilaminar disk; epiblast and hypoblast
Endometrium

17. What teratogen can cause IUGR and ADHD in a fetus? what else can this teratogen cause?
Muscular ventricular septum; no
Nicotine; preterm labor
During; instrinsic
Endoderm

18. What artery is derived branchial (aortic) arch 1?
Left horn of the sinus venosus
Dorsal; faulty positioning of genital tubercle
Week 4; week 3
Maxillary

19. From What embryonic layer do chromaffin cells arise?
Most pharyngeal constrictors - Cricothyroid - levator veli palatini; CN X (superior laryngeal branch - swallowing)
Week 8
Mesoderm
Neural crest cells

20. What is perinauds syndrome?
Increase in oxygen concentration which decreases prostaglandin concentration
Caused by compression on trocheal nerve - causes vertical gaze paralysis (associated with arnold chiari)
Bulbourethral glands (of Cowper) and Prostate gland; greater vestibular glands (of Bartholin) and Urethral and paraurethral glands (of Skene)
DHT; estrogen

21. What is the memranous interventricular formaen made from?
lumbosacral
2nd pouch
When the AP septum meets and fuses with the muscular ventricular septum to form membranous intraventricular septum - closing interventricular foramen
Primitive ventricle

22. What is the primitive streak? From what layer does it form?
Failure to recanalize; 21
Neuroectoderm
Mesoderm; epiblast
Fallopian tube - uterus - upper 1/3 of vagina

23. From what arches are the neural crest cells that form the aorticpulmonary septum derived?
not covered
3 -4 -6
Failure to recanalize; 21
IX; X

24. What does DHT turn the labioscrotal swelling into? estrogen?
Aminoglycosides
Hepatic circulation; ligamentum venosum
Scrotum; labia majora
Endoderm

25. Does deformation occur during or after the embryonic period? is it due to an extrinsic or intrinsic disruption?
Primitive ventricle
After; extrinsic
Thyroglossal duct cysts will move with swallowing while persistent cervical sinuses in lateral neck wont
Yolk sac; liver (weeks 6-30) and spleen (9-28 weeks)

26. what week do the genitalia start to have male/female characteristics? What trimester is that?
3rd and 4th arches
Week 10-12; end of 1st trimester
Endocardial cushions
Week 8

27. How do adults with annular pancreas present? and At What age?
3rd; proximal part of the internal carotid artery
Mesoderm
Neuroectoderm
20-50yrs - Abdominal pain - Postprandial fullness - Nausea - Peptic ulcers - Pancreatitis - Rarely - biliary obstruction

28. When does hcG get secreted? What does it do?up until when ?
Prosencephalon - mesencephalon - rhombencephalon
Day 6; maintains corpus luteum; 1st trimester
3rd pouch
2; 1

29. From what aortic arch does the first part of the maxillary artery arise?
From teh lung;blood from IVC in RA to LA; fossa ovalis
Prosencephalon
1st
DiGeorge

30. From What embryonic layer is the spleen from?
Pataus; fetal alcohol syndrome
Mesoderm; epiblast
Mesoderm
Most pharyngeal constrictors - Cricothyroid - levator veli palatini; CN X (superior laryngeal branch - swallowing)

31. What is hypoplasia? is primordial tissue present?
Incomplete; yes
Aortic arch (from left side); right subclavian (on the right)
Nutrient and gas exchange
IX; X

32. What type of blood do umbilical veins carry? From where to where?
Decreased separation of hemispheres across midline; cyclopia
Failure of the urachus to obliterate; outpouching of the bladder
Oxygenated; placenta to fetus (IVC)
1st arch neural crest fails to migrate --> mandibular hypoplasia - facial abnormalities (cleft palate - decreased slanting of palpebral fissures)

33. Which parts of the pancreas contribute to the head - uncinate process and main pancreatic duct?
Dorsal and ventral buds
Week 3-8
1st
3rd pouch

34. What secretes hCG?
Nutrient and gas for exchange; endometrium
Mental retardation - holoprosencephaly - facial features - fistulas
Synctiotrophoblast
Ebsteins anomaly; tricuspid atresia

35. From what region of the brain does the aqueduct form?
Failure of the urachus to obliterate
Mesencephalon
Rhombencephalon
Aminoglycosides

36. what separates the atria from the ventricles?
Caused by compression on trocheal nerve - causes vertical gaze paralysis (associated with arnold chiari)
Endocardial cushions
Mesonephros; male genital system
Deformation

37. What artery is derived branchial (aortic) arch 6?
Rostral fold closure ; lateral fold closure; lateral fold closure; caudal fold closure
Oxygenated; placenta to fetus (IVC)
Pulm art (prox) and ductus arteriosus
20-50yrs - Abdominal pain - Postprandial fullness - Nausea - Peptic ulcers - Pancreatitis - Rarely - biliary obstruction

38. From where to Where is the foregut derivative? midgut? hindgut?
Mesoderm
Failure of bony spinal canal to fuse; no; lower vertebral levels
Dorsal and ventral buds
Pharynx to duodenum; duodenum to transverse colon; distal transverse colon to rectum

39. From What embryonic layer does the neurohypophysis arise?
Neuroectoderm
Common carotid and internal carotid
Arnold chiari; syringomyelia
Prenatal and perinatal

40. What embryonic structure gives rise to the ascending aorta? what else does it give rise to?
Surface ectoderm
Truncus arteriosus; pulmonary trunk
Arnold Chiari and Dandy Walker; Arnold Chiari; Dandy Walker; Arnold Chiari
ACE inhibitors - HCTZ

41. What three components make up the branchial/pharyngeal apparatus?
Alkylating agents
Grooves/clefts; arches; pouches
8
Neuroectoderm

42. What teratogens can cause renal damage in the fetus?
ACE inhibitors - HCTZ
Ebsteins anomaly; tricuspid atresia
Ventral and dorsal parts fail to fuse at 8th week; 2 pancreatic ducts!- more prone to pancreatitis
Epispadias

43. From what are the umbilical arteries and veins derived from?
3rd pouch
Allantois
primary palate
Endoderm

44. When does organogenesis occur?
Rhombencephalon
4th/5th branchial pouches
Week 8
Week 3-8

45. what bone/cartilage and nerves are derived from branchial arch 3?
Greater horn of hyoid; CN IX (styloPharyngeus)
elevated AFP
4th pouch
Umbilical - midgut herniates through umbilical ring; SMA

46. What embryological structure gives rise to the smooth part of the right atrium?
Ventral; failure of urogenital folds to close
Right horn of the SV
Valproate acid
They are the edge of neural plate folding; all over the body

47. What is another name for the mesonephric duct? paramesonephric?
Wolffian; mullerian
Neuroectoderm
Amniotic epithelium
Neural plate; closes by week 4

48. Which part of pancreas contribute to body? tail? isthmus? accessory pancreatic duct?
Ventral bud
Decreases
Fetal alcohol syndrome; mental retardation
hypertrophy

49. What is duodenal atresia usually due to? What trisomy is it most often seen in?
Failure to recanalize; 21
Hypospadias
Bulbos Cordis; right ventricle entirely
Neural crest cells

50. Which branchial derivative creates the middle ear cavity - eustachian tube and mastoid air cells?
First branchial pouch
Week 4
Duodenum to transverse colon; distal transverse colon to rectum
Absent cerebellar vermis; cystic enlargement of 4th ventricle