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 are the two walls of the prosencephalon and What do they become?
Arnold Chiari and Dandy Walker; Arnold Chiari; Dandy Walker; Arnold Chiari
2nd; 2nd
They are the edge of neural plate folding; all over the body
Cerebral hemisphere - thalami

2. From which branchial derivative does the anterior 2/3 of the tongue develop?
2nd pouch
can make cells
Cerebellar tonsillar herniation through foramen magnum
1st branchial arch

3. What does the ureteric bud interact with and What does it induce it to become?
monoamniotic
Metanephric mesenchyme; differentiation and formation of glomerulus and renal tubules to distal convoluted tubule
Urogenital sinus; wolffian duct; mullerian duct; urogenital sinus; wolffian duct; wolffian duct; mullerian; mullerian
Lithium

4. Blood coming in the umbilical vein is ____ saturated
80%
Cerebellar tonsillar herniation through foramen magnum
Amniotic cavity and yolk sac
Neuroectoderm

5. what junction is the last to canalize? what implications does this have down the line?
Pataus; fetal alcohol syndrome
Uretopelvis; most common site for obstruction (hydronephrosis) in fetus
primary palate
Ovarian ligament and round ligament of uterus; anchors testes within scrotum

6. What does the midgut form? hindgut?
Pharynx to duodenum; duodenum to transverse colon; distal transverse colon to rectum
Week 3-8
Duodenum to transverse colon; distal transverse colon to rectum
Ectoderm

7. From What embryonic layer does a craniopharygioma arise?
Mid gut to yolk sac; omphalomesenteric duct; 7th week
Right horn of the SV
Cytotrophoblast and synctiotrophoblast
Surface ectoderm

8. What is the memranous interventricular formaen made from?
Endoderm
When the AP septum meets and fuses with the muscular ventricular septum to form membranous intraventricular septum - closing interventricular foramen
Ventral bud
Occiptal

9. what muscles are derived from branchial arch 4? CN?
Most pharyngeal constrictors - Cricothyroid - levator veli palatini; CN X (superior laryngeal branch - swallowing)
Neural crest cells
ACE inhibitors - HCTZ
Neuroectoderm

10. what chemo drugs can cause neural tube defects in the fetus?
Deoxygenated blood; fetal internal iliac arteries to placenta
Neuroectoderm
Folate antagonists
Maxillary and medial nasal processes

11. What causes tetralogy of Fallot?
External auditory meatus
Grooves/clefts; arches; pouches
Ectoderm - mesoderm - endoderm; epiblast - primitive streak - hypoblast; week 3
Skewed development of AP septum

12. Which branchial apparatus derivative makes the tympanic membrane of the ear?
8
Aberrant development of 3rd and 4th pouches; t cell def (thymic aplasia) - hypocalcemia (failure of parathyroid development) - CF and CV defects
Failure to recanalize; 21
Membrane - all 3 from 1st appartus

13. When does hcG get secreted? What does it do?up until when ?
Hepatic circulation; ligamentum venosum
Fetal alcohol syndrome; mental retardation
Mesoderm
Day 6; maintains corpus luteum; 1st trimester

14. What germ layer correlates with the branchial pouches?
Dorsal ventral axis
Lacunae in between the chorionic villi
Endoderm
1st branchial arch

15. what bone/cartilage and nerves are derived from branchial arch 1?
Reicherts cartilage: Stapes - Styloid process - Lesser horn of hyloid - Stylohyoid ligament and CN VII
Obliterated; forms tunica vaginalis
Meckels cartilage: mandible - malleus - INCUS - sphenoMandibular ligament; CN V2 and V3
Week 4

16. Which CN accounts for the anterior 2/3 of the tongues sensation and pain? how about taste?
Increased AFP and acetycholinesterase (not ACh!) in CSF
Pulm art (prox) and ductus arteriosus
V3; VII
Congenital and chromosomal abnormalities

17. From where is the pancreas derived? the spleen?
Deformation
Membrane - all 3 from 1st appartus
septum primum and/or secundum
Foregut; dorsal mesentery (mesodermal)

18. What hormone is hcG structurally similar too?
LH
Folate antagonists
Spinothalamic first
Bones - cartilage - and nerves

19. When does the blastocyst split into two disks? What is this disk called? What are the two germ layers called?
Mesoderm
Week 2; bilaminar disk; epiblast and hypoblast
...
Most pharyngeal constrictors - Cricothyroid - levator veli palatini; CN X (superior laryngeal branch - swallowing)

20. On what side is the abnormal opening in epispadias? What causes it?
Dorsal; faulty positioning of genital tubercle
5th
Persistance of herniation of abdominal contents into umbilical cord covered by peritoneum; 13 - 18
IX; X

21. What weeks are considered the 'embryonic period'?
Failure to spiral (aorta coming out of RV and PA coming out of left ventricle)- two completely separate systems
Neural crest cells
Excessive resorption of septum primum or secondum (or both)
Week 3-8

22. What are the three results of having pathology in the aorticopulmonary septum?
Grooves/clefts; arches; pouches
...
...
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)

23. What type of - amnios does bilateral agenesis form? What three symptoms does this cause?
Surface ectoderm
monoamniotic
Oligohydramnios
Incomplete; yes

24. What causes the increase in left atrial pressure to close the fossa ovale?
Annular pancrease
Persistent connection between amniotic cavity and spinal canal; low folic acid
Folate antagonists
Decreased pulmonary resistance in the pulmonary vasculature

25. What does DHT turn the urogenital folds into? estrogen?
Ventral; failure of urogenital folds to close
Ventral shaft of penis (penile urethra); labia minora
Base of limbs in the zone of polarizing activity; ant - post
Obliterated; forms tunica vaginalis

26. From where does the prostate develop? seminal vesicles? fallopian tube? lower 2/3 of the vagina? ejaculatory duct? epididymis? uterus? upper 1/3 of the vagina?
Urogenital sinus; wolffian duct; mullerian duct; urogenital sinus; wolffian duct; wolffian duct; mullerian; mullerian
Neural crest cells
T neuroectoderm
Pronephros - mesonephros - metanephros; pronephros; most cranially

27. From What embryonic layer does the pineal gland arise?
Decidual basalis
Neuroectoderm
Prenatal and perinatal
Deoxygenated blood; fetal internal iliac arteries to placenta

28. _____________is common in 1st born males
Physiologic incomplete muscular ventricular septum
pyloric stenosis
...
Endometrium

29. What axis is Wnt 7 responsible for developing?
Lithium
Dorsal ventral axis
Bone/cartilage and nerves
Respiratory distress syndrome

30. When does organogenesis occur?
mesoderm
Decreases
Week 3-8
Scrotum; labia majora

31. Cleft lip is a failure of formation of the...
No organ in each; agenesis no primordial tissue
Week 8
Thyroglossal duct cysts will move with swallowing while persistent cervical sinuses in lateral neck wont
primary palate

32. From What embryonic layer do the parafollicular cells of the thyroid arise?
Neural crest cells
Medial palatine processes
Fluid filled cavity in spinal cord; C8- T1; arnold chiari II
Gastric outlet obstruction (bilious vomiting - feeding intolerance - abdominal distention)

33. What embryological structure gives rise to the trabeculated part of the left and right atrium?
Muscles and arteries
Neuroectoderm
Primitive atrium
Failure of the urachus to obliterate

34. What components do the neural crest cells of the branchial arches give rise to?
Failure of bony spinal canal to fuse; no; lower vertebral levels
Thyroid - cricoid - arytenoids - corniculate cuneiform
Apical ectodermal ridge
Bones - cartilage - and nerves

35. What is annular pancreas associated with in infants?
secondary palate
Polyhydramnios - Down syndrome - Esophageal/duodenal atresia - Imperforate anus - Meckel diverticulum
Endoderm
Pharynx to duodenum; duodenum to transverse colon; distal transverse colon to rectum

36. What is germinal matrix hemorrhage associated with?
All 3
Neural plate; closes by week 4
Respiratory distress syndrome
pyloric stenosis

37. what bone/cartilage and nerves are derived from branchial arch 2?
Neural crest cells
Reicherts cartilage: Stapes - Styloid process - Lesser horn of hyloid - Stylohyoid ligament and CN VII
Rhombencephalon
Base of limbs in the zone of polarizing activity; ant - post

38. what bone/cartilage and nerves are derived from branchial arch 3?
Turners; inferior
Obliterated; forms tunica vaginalis
Neural crest cells
Greater horn of hyoid; CN IX (styloPharyngeus)

39. What are the two components of the placenta? From What do they form? which one secreted hcG?
Embryonic period; 1st trimester
Ionizing
4th pouch
...

40. What causes the degeneration of the spinal cord in syringomelia?
1st branchial arch
1st arch neural crest fails to migrate --> mandibular hypoplasia - facial abnormalities (cleft palate - decreased slanting of palpebral fissures)
Fluid filled syrinx causes expansion and degeneration of cord tracts
Where the epiblast and hypoblast fuse

41. Which part of pancreas contribute to body? tail? isthmus? accessory pancreatic duct?
Ventral and dorsal parts fail to fuse at 8th week; 2 pancreatic ducts!- more prone to pancreatitis
Ventral bud
Aortic arch (from left side); right subclavian (on the right)
Mental retardation - holoprosencephaly - facial features - fistulas

42. Where is erythropoeisis in the weeks 3-8 of fetal development? Where does it occur after that? until when?
Yolk sac; liver (weeks 6-30) and spleen (9-28 weeks)
Uretopelvis; most common site for obstruction (hydronephrosis) in fetus
Mesdoerm
Decreased pulmonary resistance in the pulmonary vasculature

43. What is the leading cause of birth defects in the US? what else is this perpetrator the leading cause of?
Week 3; primitive streak formation from the epiblast makes the three layers
Incomplete fusion of paramesonephric ducts; UT abnormalities and infertility
Fetal alcohol syndrome; mental retardation
Muscles and arteries

44. What embryological structures give rise to the SVC?
Right common cardinal vein and right anterior cardinal vein
Pronephros - mesonephros - metanephros; pronephros; most cranially
Thalidomide; nausea
Cerebral hemisphere - thalami

45. From What embryonic layer do CNS neurons arise?
Ovarian ligament and round ligament of uterus; anchors testes within scrotum
Mesoderm
Neuroectoderm
Ventral bud

46. What teratogens can cause CN VIII toxicity in the fetus?
All 3
Persistence of 3rd cleft (groove) and pouch causes fistula between tonsillar area and cleft in lateral neck
Myelencephalon
Aminoglycosides

47. failure to close of what fold results in sternal defects? omphalocele? gastrochisis? bladder extrosphy?
Neuroectoderm
Nicotine; preterm labor
Aortic arch and prox part of subclavian
Rostral fold closure ; lateral fold closure; lateral fold closure; caudal fold closure

48. what drug is used to help close a PDA? what else does this drug treat?
Neuroectoderm
Incomplete; yes
Indomethacin; blocks PG production
Surface ectoderm

49. Septum primum (patent foramen oval) caused by excessive resorption of...
septum primum and/or secundum
Most pharyngeal constrictors - Cricothyroid - levator veli palatini; CN X (superior laryngeal branch - swallowing)
Thickened ectoderm at end of each developing limb
Mesoderm

50. What components do the mesoderm of the branchial arches give rise to?
Fluid filled syrinx causes expansion and degeneration of cord tracts
Bulbos Cordis; right ventricle entirely
Cranio - caudal; segmental
Muscles and arteries