Step 1 First Aid 03: Embryology

Front 1

3 axes of limb elongation

Back 1

proximo-distal
antero-posterior
dorso-ventral

Front 2

limb elongation occurs along ___ axis
and is driven by ___ released from ___
and nested expression of ___

Back 2

proximo-distal
FGF
apical epidermal ridge (AER)
Hoxa genes

Front 3

antero-posterior differentiation of limb is driven by ___ which originates at ___

Back 3

Shh gradient
zone of polarizing activity (ZPA)

Front 4

dorso-ventral differentiation of limb is driven by ___ released from ___

Back 4

WNT-7
AER

Front 5

hCG secretion begins with ___

Back 5

implantation

Front 6

peak susceptibility to teratogens is during ___
this corresponds to ___

Back 6

weeks 3--8
organogenesis

Front 7

genitalia are male/female at week ___

Back 7

10

Front 8

rule of 2's

Back 8

2nd week
2 germ layers
2 cavities (amnion, yolk sac)
2 placental components

Front 9

rule of 3's

Back 9

3rd week
3 germ layers

Front 10

rule of 4's

Back 10

4th week
4 heart chambers
4 limb buds

Front 11

2 embryonic layers in thyroid

Back 11

endoderm (follicular cells)
neural crest (parafollicular cells)

Front 12

2 embryonic layers in adrenals

Back 12

mesoderm (cortex)
neural crest (medulla)

Front 13

2 embryonic layers in heart

Back 13

mesoderm (myocardium)
neural crest (aorticopulmonary septum)

Front 14

2 kinds of ectoderm in eye

Back 14

surface ectoderm (lens, epitelial lining of retina)
neuroectoderm (retina)

Front 15

VACTERL is ___
these are all ___ defects

Back 15

vertebral
anal atresia
cardiac
TE fistula
renal
limb defects
mesoderm

Front 16

fetal damage from ACEI

Back 16

renal

Front 17

fetal damage from alkylating agents

Back 17

missing fingers

Front 18

fetal damage from aminoglycosides

Back 18

CN8

Front 19

fetal damage from cocaine

Back 19

abruptio plancentae

Front 20

fetal damage from DES

Back 20

vaginal clear cell adenoca

Front 21

fetal damage from folate antagonists

Back 21

NTD

Front 22

fetal damage from iodide deficiency

Back 22

congenital hypothyroidism

Front 23

fetal damage from iodide excess

Back 23

congenital goiter

Front 24

fetal damage from Li

Back 24

atrialized RV (ebstein's anomaly)

Front 25

fetal damage from maternal DM

Back 25

caudal regression

Front 26

caudal regressinon may present as ___ (2)

Back 26

anal atresia
sirenomyelia

Front 27

fetal damage from smoking (4)

Back 27

preterm labor
placental problems
IUGR
ADHD

Front 28

fetal damage from tetracyclines

Back 28

discolored teeth

Front 29

fetal damage from VPA

Back 29

NTD (from folate malabsorption)

Front 30

fetal damage from vitamin A (2)

Back 30

cleft palate
cardiac defects

Front 31

fetal damage from warfarin

Back 31

bone deformities
fetal hemorrhage

Front 32

___ is the leading cause of fetal malformations in the US

Back 32

fetal alcohol syndrome

Front 33

fetal alcohol syndrome includes (7)

Back 33

developmental retardation
microcephaly
holoprosencephaly
facial abnormalities
limb dislocation
heart fistula
lung fistula

Front 34

mechanism of fetal alcohol syndrome

Back 34

inhibited cell migration

Front 35

chorion forms at day ___
amnion forms at day ___

Back 35

3
8

Front 36

3 possible chorionicity/amnionicity combinations for twins

Back 36

dichorionic diamniotic
monochorionic diamniotic
monochorionic monoamniotic

Front 37

dichorionic diamniotic pregnancy happens when ___ (2)

Back 37

zygote splits before day 3
dizygotic pregnancy

Front 38

monochorionic diamniotic pregnancy happens when ___

Back 38

zygote splits between days 3 and 8

Front 39

monochorionic monoamniotic pregnancy happens when ___

Back 39

zygote splits after day 8

Front 40

risk of conjoined twinning occurs with ___ pregnancy

Back 40

monochorionic monoamniotic

Front 41

hCG is made by ___
it does ___ during ___
it resembles ___ in structure

Back 41

syncitiotrophoblast
makes corpus luteum secrete P
1st trimester
LH

Front 42

maternal side of placenta

Back 42

decidua basalis

Front 43

3 layers between fetal vessel and maternal blood/tissue

Back 43

mesoderm
cytotrophoblast
syncytiotrophoblast

Front 44

normal contents of umbilical cord (4)

Back 44

2 umbilical arteries
1 umbilical vein
urachus

Front 45

umbilical abnormality associated with congenital anomalies

Back 45

single umbilical a.

Front 46

umbilical arteries and veins are derived from ___

Back 46

allantois

Front 47

allantois forms from ___ near ___ which inserts into ___,
which becomes ___
this occurs at ___ week

Back 47

yolk sac
hindgut
body stalk
umbilical cord
3rd

Front 48

allantois becomes ___
this does ___

Back 48

urachus
conveys urine from bladder to yolk sac

Front 49

4 urachal abnormalities

Back 49

patent urachus
vesicourachal diverticulum
urachal sinus
urachal cyst

Front 50

patent urachus pw

Back 50

urine from umbilicus

Front 51

urachal sinus pw

Back 51

recurrent infection

Front 52

vitelline duct connects ___ and ___
it is aka ___
it closes at ___

Back 52

midgut
yolk sac
omphalomesenteric duct
7th week

Front 53

4 vitelline duct abnormalities

Back 53

vitelline fistula
Meckel's diverticulum
vitelline sinus
vitelline duct cyst

Front 54

vitelline fistula pw

Back 54

feces from umbilicus

Front 55

Meckel's diverticulum may have ___ mucosa

Back 55

gastric
pancreatic
other

Front 56

Meckel's diverticulum most commonly pw ___ but may have ___

Back 56

painless melena
RUQ pain

Front 57

Meckel's scan uses ___ to detect ___

Back 57

Tc99
gastric mucosa

Front 58

truncus arteriosus becomes ___ (2)

Back 58

ascending aorta
pulmonary trunk

Front 59

bulbus cordis becomes ___ (2)

Back 59

RV
LVOT

Front 60

primitive ventricle becomes ___

Back 60

LV

Front 61

primitive atria become ___ (2)

Back 61

trabeculated RA
trabeculated LA

Front 62

sinus venosus becomes ___ (3)

Back 62

smooth part of RA
oblique vein of LA
coronary sinus

Front 63

L horn of sinus venosus becomes ___

Back 63

coronary sinus

Front 64

R horn of sinus venosus becomes ___

Back 64

smooth part of RA

Front 65

SVC is made from ___ (2)

Back 65

R common cardinal vein
R anterior cardinal vein

Front 66

aorticopulmonary septum develops from ___ to __ and becomes ___

Back 66

superior
inferior
membranous IV septum

Front 67

ostium primum is bounded by ___ from above and ___ from below
septum primum grows from ___ to ___

Back 67

septum primum
posterior endocardial cushion
cardiac base
posterior endocardial cushion

Front 68

ostium secundum develops from ___

Back 68

perforations in septum primum

Front 69

septum secondum develops at ___
as it grows, ___ regresses
it grows until it reaches ___

Back 69

R of ostium primum
top part of septum primum
top edge of bottom part of septum primum

Front 70

4 hematopoietic tissues in fetus, in order of action

Back 70

yolk sac
liver
spleen
bone marow

Front 71

yolk sac makes blood from week ___ to ___

Back 71

3
8

Front 72

liver makes blood from week ___ to ___

Back 72

6
30

Front 73

spleen makes blood from week ___ to ___

Back 73

9
28

Front 74

bone marrow makes blood from week ___ to ___

Back 74

28
death

Front 75

O2 sat in umbilical vein

Back 75

80%

Front 76

3 shunts in fetal circulation

Back 76

ductus venosus
foramen ovale
ductus arteriosus

Front 77

ductus venosus takes blood from ___ to ___, bypassing ___

Back 77

umbilical vein
IVC
hepatic circulation

Front 78

formen ovale takes blood from ___ to ___, bypassing ___

Back 78

RA
LA
lungs

Front 79

ductus arteriosus takes blood from ___ to ___, bypassing ___

Back 79

pulmonary trunk
descending aorta
lungs

Front 80

as a rule, blood from ___ goes through foramen ovale, and
blood from ___ goes through RV

Back 80

IVC
SVC

Front 81

after first breath ___ causes ___, causing closure of foramen ovale;
___ causes ___ causing closure of ductus arteriosus

Back 81

drop in pulmonary pressure
increased LA P
O2 rise
PG drop

Front 82

umbilical vein becomes

Back 82

ligamentum teres hepatis

Front 83

umbilical arteries become

Back 83

medial umbilical ligaments

Front 84

ductus venosus becomes

Back 84

ligamentum venosum

Front 85

foramen ovale becomes

Back 85

fossa ovalis

Front 86

allantois becomes ___ which becomes ___

Back 86

urachus
median umbilical ligament

Front 87

embryo has ___ aortic arches

Back 87

6

Front 88

1st aortic arch gives rise to ___

Back 88

part of maxillary a.

Front 89

2nd aortic arch gives rise to ___ (2)

Back 89

stapedial a.
hyoid a.

Front 90

3rd aortic arch gives rise to ___ (2)

Back 90

common carotid a.
proximal internal carotid a.

Front 91

4th aortic arch gives rise to ___ (2)

Back 91

aortic arch (on L)
proximal subclavian (on R)

Front 92

5th aortic arch gives rise to ___

Back 92

nothing!

Front 93

6th aortic arch gives rise to ___ (2)

Back 93

proximal pulmonary a.s
ductus arteriosus

Front 94

4 conditions associated wtih holoprosencephaly

Back 94

Patau
fetal alcohol syndrome
cleft lip
cleft palate

Front 95

dandy walker malformation includes (3)
it is associated with ___

Back 95

absent cerebellar vermis
enlarged 4th ventricle
cysts at internal skull base
spina bifida

Front 96

dandy walker malformation pw (4)

Back 96

macrocephaly
cerebellar dysfunction
vomiting
seizures

Front 97

3 parts of branchial apparatus

Back 97

arches
clefts
pouches

Front 98

branchial clefts are made from ___

Back 98

ectoderm

Front 99

branchial arches are made from ___

Back 99

mesoderm

Front 100

branchial pouches are made from ___

Back 100

endoderm

Front 101

1st branchial cleft becomes ___

Back 101

external auditory meatus

Front 102

2nd-4th branchial clefts become ___

Back 102

cervical sinuses

Front 103

persistent cervical sinus becomes ___

Back 103

branchial cleft cyst

Front 104

4 cartilaginous derivatives of 1st arch
collectively they are called ___

Back 104

mandible
malleus
incus
spheno-mandibular ligament
Meckel's cartilage

Front 105

5 muscles derived from 1st arch

Back 105

muscles of mastication
mylohyoid
anterior belly of digastric
tensor tympani
tensor veli palatini

Front 106

1st arch muscles are innervated by ___

Back 106

V2
V3

Front 107

artery derived from 1st arch

Back 107

maxillary

Front 108

4 cartilaginous derivatives of 2nd arch
collectively these are called ___

Back 108

stapes
styloid process
lesser horn of hyoid
stylohyoid ligament
Reichert's cartilage

Front 109

muscles derived from 2nd arch (4)

Back 109

muscles of facial expression
stapedius
stylohyoid
posterior belly of digastric

Front 110

2nd arch muscles are innvervated by ___

Back 110

CN7

Front 111

2 arteries derived from 2nd arch

Back 111

stapedial
hyoid

Front 112

cartilaginous derivative of 3rd arch

Back 112

greater horn of hyoid

Front 113

muscle derived from 3rd arch

Back 113

stylopharyngeus

Front 114

muscle of 3rd arch is innervated by

Back 114

CN9

Front 115

2 cartilaginous derivatives of 4th arch

Back 115

thyroid cartilage
epiglottic cartilage

Front 116

3 muscles derived from 4th arch

Back 116

pharyngeal constrictors
levator veli palatini
cricothyroid

Front 117

4th arch muscles are innervated by ___

Back 117

superior laryngeal branch of CN10

Front 118

3 cartilaginous derivatives of 6th arch

Back 118

cricoid
arytenoid
corniculate

Front 119

muscles derived from 6th arch

Back 119

intrinsic muscles of larynx except cricothyroid

Front 120

6th arch muscles are innvervated by ___

Back 120

recurrent laryngeal branch of CN10

Front 121

treacher collins is caused by problem with ___ arch
it is caused by deficient ___

Back 121

1st
neural crest cell migration

Front 122

pharyngo-cutaneous fistula is caused by ___

Back 122

persistence of 3rd branchial cleft and pouch

Front 123

posterior 1/3 of tongue is formed by arches ___

Back 123

3
4

Front 124

1st branchial pouch becomes (3)

Back 124

eustachian tube
middle ear cavity
mastoid air cells

Front 125

2nd branchial pouch becomes

Back 125

epithelium of palatine tonsil

Front 126

dorsal wings of 3rd branchial pouch become

Back 126

inferior PT glands

Front 127

ventral wings of 3rd branchial pouch become

Back 127

thymus

Front 128

4th branchial pouch becomes (2)

Back 128

superior PT glands
parafollicular C cells

Front 129

5th branchial pouch becomes

Back 129

parafollicular C cells

Front 130

DiGeorge is problems with ___

Back 130

3rd + 4th pouches

Front 131

3 tumors of MEN 2A
they are all derived from ___
they are caused by ___

Back 131

pheochromocytoma
parathyroid
medullary thyroid
neural crest cells
RET protooncogene mutation

Front 132

___ is formed by contact of 1st branchial cleft with 1st branchial pouch
this becomes ___

Back 132

branchial membrane
tympanic membrane

Front 133

anterior 2/3 of tongue is from ___ arch
touch is from ___
taste is from ___

Back 133

1st
V3
CN7

Front 134

posterior 1/3 of tongue is from ___ arch
touch is from ___
taste is from ___

Back 134

3rd
CN9
CN9

Front 135

extreme posterior of tongue is from ___ arch
touch is from ___
taste is from ___

Back 135

4th
CN10
CN10

Front 136

taste fibers from ___ go to ___ nucleus

Back 136

CN7
CN9
CN10
NTS

Front 137

thyroid originates from ___ which becomes ___

Back 137

pharyngeal endoderm
foramen cecum

Front 138

during descent of thyroid it is connected to ___ by ___

Back 138

foramen cecum
thyroglossal duct

Front 139

thyroglossal duct may persist as ___ (2)

Back 139

pyramidal lobe of thyroid
thyroglossal duct cyst

Front 140

thyroglossal duct cyst may be distinguished from branchial cleft cyst by ___ (2)

Back 140

location
movement on swallowing (thyroglossal will move)

Front 141

cleft lip is caused by failure of ___ (2) to fuse
these form ___

Back 141

maxillary prominence
medial nasal prominence
primary palate (palate anterior to incisive foramen)

Front 142

cleft palate is caused by failure of ___ (3) to fuse
these form ___

Back 142

lateral palatine processes
median palatine process
nasal septum
2' palate

Front 143

4 contributors to diaphragm

Back 143

septum transversum
pleuroperitoneal folds
body wall
dorsal esophageal mesentery

Front 144

septum transversum becomes ___ of diaphragm

Back 144

central tendon

Front 145

dorsal esophageal mesentery becomes ___ of disphragm

Back 145

crura

Front 146

defective closure of rostral fold causes ___

Back 146

sternal defects

Front 147

defective closure of lateral fold(s) causes ___ (2)

Back 147

omphalocele
gastroschisis

Front 148

defective closure of caudal fold causes ___

Back 148

bladder exstrophy

Front 149

jejunal, ___ and ___ atresia is caused by ___
pathology is aka ___

Back 149

ileal
colonic
vascular accident
apple peel atresia

Front 150

midgut herniates out through ___ at ___
it returns at ___, after which it ___s

Back 150

umbilical ring
6th week
10th week
rotates around SMA

Front 151

most common TE fistula has ___ (2)

Back 151

blind upper esophagus
lower esophagus connected to trachea

Front 152

TE fistula pw (2)

Back 152

cyanosis
choking/vomiting with feeding

Front 153

prenatal sign of TE fistula

Back 153

polyhydramnios

Front 154

CXR sign of TE fistula

Back 154

air bubble (upper esophageal pouch)

Front 155

congenital pyloric stenosis usually presents at ___
it is more common in ___s

Back 155

2 wks
1st born males

Front 156

pancreas is derived from ___gut

Back 156

fore

Front 157

two components of embryonic pancreas

Back 157

dorsal bud
ventral bud

Front 158

ventral pancreatic bud makes ___ (3)

Back 158

head
uncinate process
main pancreatic duct (Wirsung)

Front 159

dorsal pancreatic bud makes ___ (4)

Back 159

body
tail
isthmus
accessory duct (Santorini)

Front 160

ventral bud rotates in ___ direction (assuming axial view + radiological convention)

Back 160

CCW

Front 161

SMA is ___ with respect to body of pancreas,
and ___ with respect to uncinate

Back 161

posterior
anterior

Front 162

2 abnormalities of pancreatic bud fusion

Back 162

annular pancreas
pancreas divisum

Front 163

annular pancreas can cause ___

Back 163

duodenal stenosis

Front 164

in pancreas divisum, ___ and ___ don't connect

Back 164

wirsung
santorini

Front 165

3 stages of kidney development

Back 165

pronephros
mesonephros
metanephros

Front 166

pronephros develops at ___
mesonephros is present at ___
metanephros first appears at ___ and develops until ___

Back 166

week 4
1st trimester
week 5
week 32-36

Front 167

metanephros starts as ___ located at ___

Back 167

ureteric bud
caudal end of mesonephros

Front 168

mesonephros becomes ___ (4)

Back 168

seminal vesicles
epididymis
ejaculatory duct
ductus deferens

Front 169

ureteric bud gives rise to urinary system from ___ to ___, inclusively
it is canalized by ___

Back 169

collecting duct
ureter
week 10

Front 170

___ aka ___ gives rise to urinary system from glomerulus to distal tubule
it is induced by ___

Back 170

metanephric mesenchyme
metanephrogenic blastema
ureteric bud

Front 171

3 effects of oligohydramnios (as in potter's syndrome)

Back 171

limb deformity
facial deformity
pulmonary hypoplasia

Front 172

T/F: horseshoe kidneys function normally

Back 172

true

Front 173

horseshoe kidneys fuse at ___
they are trapped by ___ which causes ___

Back 173

inferior pole
IMA
they stay low in abdomen

Front 174

paramesonephric ducts aka ___ become ___ (3)

Back 174

Müllerian ducts
fallopian tubes
uterus
upper 1/3 of vagina

Front 175

in men, mesonephric ducts persist because of ___ released by ___
paramesonephric duct development is inhibited by ___ released by ___

Back 175

testosterone
Leydig
MIS
Sertoli cells

Front 176

___ drives male genital differentiation
___ drives female

Back 176

DHT
E

Front 177

genital tubercle becomes ___ (3) in men and ___ (2) in women

Back 177

glans penis
corpora cavernosa
corpus spongiosum
glans clitoris
vestibular bulbs

Front 178

urogenital sinus becomes ___ (2) in men and ___ (2) in women

Back 178

bulbourethral glands (Cowper)
prostate
greater vestibular glands (Bartholin)
urethral/paraurethral glands (Skene)

Front 179

urogenital folds become ___ in men and ___ in women

Back 179

ventral shaft of penis
labia minora

Front 180

labioscrotal swelling becomes ___ in men and ___ in women

Back 180

scrotum
labia majora

Front 181

hypospadias is caused by ___
epispadias is caused by ___
___ is more common

Back 181

deficient closure of urethral folds
mispositioning of genital tubercle
hypospadias

Front 182

complication of hypospadias

Back 182

UTI

Front 183

epispadias is associated with ___

Back 183

bladder exstrophy