Usmle Step 1 Review - Embryology

Front 1

HOX organizes the embryo on this axis

Back 1

craniocaudal

Front 2

Wnt-7 organizes the embryo on this axis

Back 2

dorsal-ventral

Front 3

SHH organizes the embryo along this axis

Back 3

anterior-posterior, produced at the base of the limbs in the ZPA

Front 4

FGF is responsible for what in the embryo?

Back 4

limb lengthening

Front 5

germ layer for adenohypophysis

Back 5

surface ectoderm

Front 6

germ layer for lens of eye

Back 6

surface ectoderm

Front 7

germ layer for salivary, sweat and mammary glands

Back 7

surface ecdoderm

Front 8

germ layer for neurohypophysis

Back 8

neuroectoderm

Front 9

germ layer for oligodendrocytes, astrocytes, ependymal cells, retina

Back 9

neuroectoderm

Front 10

germ layer for optic nerve

Back 10

neuroectoderm (it's myelinated by oligodendrocytes, too)

Front 11

germ layer for peripheral nerves, including autonomic, dorsal root ganglia, and cranial nerves

Back 11

neural crest

Front 12

germ layer for parafollicular (C) cells of the thyroid

Back 12

neural crest

Front 13

germ layer for pia and arachnoid mater

Back 13

neural crest

Front 14

germ layer for odontoblast and bones of the skull

Back 14

neural crest

Front 15

germ layer for connective tissue

Back 15

mesoderm

Front 16

germ layer for pleura, peritoneum, pericardium

Back 16

mesoderm

Front 17

germ layer for internal reproductive organs, including upper 1/3 of vagina

Back 17

mesoderm

Front 18

germ layer for blood

Back 18

mesoderm

Front 19

germ layer for heart

Back 19

mesoderm

Front 20

germ layer for dermis

Back 20

mesoderm

Front 21

germ layer for ovaries/testes

Back 21

mesoderm

Front 22

germ layer for thymus

Back 22

endoderm

Front 23

germ layer for thyroid (except C cells)

Back 23

endoderm

Front 24

germ layer for pharyngotympanic (Eustachian) tube

Back 24

endoderm

Front 25

germ layer for bladder, urethra, and lower vagina

Back 25

endoderm

Front 26

teratogen causing missing digits, among other things

Back 26

alkylating agents

Front 27

teratogen causing CNVIII toxicity

Back 27

aminoglycosides

Front 28

teratogen causing neural tube defects, craniofacial defects, fingernail hypoplasia, DD, and IUGR

Back 28

carbamazepine

Front 29

teratogen causing Ebstein's anomaly (which is an atrialized right ventricle)

Back 29

lithium

Front 30

teratogen causing fetal hydantoin syndrome, which includes microcephaly, craniofacial defects, hypoplastic nails and distal phalanges, cardiac anomalies, DD, and IUGR

Back 30

phenytoin

Front 31

teratogen causing thecomelia

Back 31

thalidomide

Front 32

teratogen causing neural tube defects via inhibition of maternal folate absorption

Back 32

valproate

Front 33

teratogen causing bone deformities, ophthalmic abnormalities, fetal hemorrhage, and spontaneous abortion

Back 33

warfarin

Front 34

teratogen causing, among other things, limb dislocation and heart/lung fistulae

Back 34

alcohol

Front 35

teratogen causing placental abruption

Back 35

cocaine

Front 36

teratogen causing preterm labor, placental problems, IUGR, ADHD

Back 36

nicotine

Front 37

teratogen causing congenital goiter

Back 37

lack of iodide

Front 38

teratogen causing congenital hypothyroidism

Back 38

iodide excess

Front 39

maternal condition causing caudal regression syndrome, CHD, and neural tube defects

Back 39

maternal diabetes

Front 40

If the embryo splits between the two-cell and morula stage, you get...

Back 40

dichorionic, diamniotic twins w/ fused or separate placentas

Front 41

If the embryo splits between the morula and the blastocyst stage (4-8 d), you get...

Back 41

monochorionic, diamniotic twins (75% of identical twins)

Front 42

If the embryo splits between the blastocyst and bilaminar disc stage (8-12 d), you get...

Back 42

monochorionic, monoamniotic twins

Front 43

If the embryo splits after the bilaminar disc stage (>13 days), you get...

Back 43

monochorionic, monoamniotic conjoined twins

Front 44

The umbilical arteries arise from the...

Back 44

fetus's internal iliacs

Front 45

The umbilical vein drains into the...

Back 45

ductus venosus, which becomes the IVC

Front 46

Describe the path of oxygenated blood in the fetus.

Back 46

Placenta --> umbilical vein --> ductus venosus --> IVC --> RA --> foramen ovale --> LA --> LV --> aorta

Front 47

Describe the path of deoxygenated blood in the fetus starting at the SVC.

Back 47

SVC --> RA --> RV --> pulmonic trunk --> ductus arteriosus --> aorta --> common, internal iliacs --> umbilical arteries

Front 48

What do you use to keep a PDA open?

Back 48

misoprostol

Front 49

The bulbus cordis becomes...

Back 49

the RV and the outflow tracts of RV and LV

Front 50

The primitive ventricle becomes the...

Back 50

trabeculated RV, LV

Front 51

The primitive atrium becomes the ...

Back 51

trabeculated RA and LA

Front 52

The L horn of sinus venosus becomes...

Back 52

the coronary sinus

Front 53

The R horn of sinus venosus becomes...

Back 53

the smooth part of RA

Front 54

The right common cardinal vein and right anterior cardinal vein fuse to become the...

Back 54

SVC

Front 55

Site of fetal hematopoiesis from 0-12 wks

Back 55

yolk sac

Front 56

major site of fetal hematopoiesis from 10-30 weeks

Back 56

liver

Front 57

minor site of fetal hematopoiesis from 15-30 weeks

Back 57

spleen

Front 58

week at which marrow hematopoiesis is the major site

Back 58

30 wks (but liver continues past 40 wks)

Front 59

The maxillary artery is derived from the ___ aortic arch.

Back 59

First aortic arch

Front 60

The stapedial and hyoid arteries are derived from the ___ aortic arch.

Back 60

second aortic arch

Front 61

The common carotids and proximal part of internal carotids are derived from the ___ aortic arch.

Back 61

Third aortic arch.

Front 62

The aortic arch and the proximal right subclavian artery are derived from the ___ aortic arch.

Back 62

Fourth aortic arch.

Front 63

The proximal pulmonary arteries and ductus arteriosus are derived from the ___ aortic arch.

Back 63

Sixth aortic arch.

Front 64

The metencephalon becomes the...

Back 64

pons and cerebellum

Front 65

The myelencephalon becomes the...

Back 65

medulla

Front 66

The third ventricle is bordered by the...

Back 66

thalamus

Front 67

The cerebral aqueduct is bordered by the...

Back 67

midbrain

Front 68

The upper 4th ventricle is bordered by the...

Back 68

pons

Front 69

The lower 4th ventricle is bordered by the...

Back 69

medulla

Front 70

The ectoderm gives rise to the brachial arches, clefts, or pouches?

Back 70

Ectoderm --> clefts

Front 71

The mesoderm/neural crest gives rise to the branchial clefts, arches, or pouches?

Back 71

arches

Front 72

The endoderm gives rise to the branchial clefts, arches, or pouches?

Back 72

pouches

Front 73

The external auditory meatus is derived from the ___ branchial ___.

Back 73

first branchial cleft

Front 74

The middle ear cavity, pharyngotympanic tube and mastoid air cells are derived from the ___ branchial ___.

Back 74

first branchial pouch

Front 75

The epithelial lining of the palatine tonsil is derived from the ___ branchial ___.

Back 75

second branchial pouch

Front 76

The inferior parathyroids and the thymus are derived from the ___ branchial ____.

Back 76

third branchial pouch

Front 77

The superior parathyroids are derived from the ___ branchial ___.

Back 77

fourth branchial pouch

Front 78

CN V2 and V3 are derived from the ___ branchial ___.

Back 78

first branchial arch

Front 79

CN VII is derived from the ___ branchial ___.

Back 79

second branchial arch

Front 80

CNIX is derived from the ___ branchial ___.

Back 80

third branchial arch

Front 81

The superior laryngeal branch of CNX is derived from the ___ branchial ___.

Back 81

fourth branchial arch

Front 82

The recurrent laryngeal branch of CNX is derived from the ___ branchial ___.

Back 82

sixth branchial arch

Front 83

The mandible, malleus, and incus are derived from the ___ branchial ___ (Meckel's cartilege).

Back 83

first branchial arch

Front 84

The muscles of mastication, myelohyoid, anterior belly of digastric, tensor tympani, and tensor veli palatini are derived from the ___ branchial ___.

Back 84

first branchial arch

Front 85

The stapes, styloid process, lesser horn of the hyoid are derived from the ___ branchial ___ (Reichert's cartilege).

Back 85

second branchial arch

Front 86

The muscles of facial expression as well as stapedius, stylohoid, and posterior belly of the digastric are derived from the ___ branchial ___.

Back 86

second branchial arch

Front 87

The greater horn of the hyoid is derived from the ___ branchial ___.

Back 87

third branchial arch

Front 88

The stylopharyngeus muscle is derived from the ___ branchial ___.

Back 88

third branchial arch

Front 89

The thyroid, cricoid, arytenoid, corniculate, and cuneiform cartileges are derived from the ___ branchial ___.

Back 89

4-6 branchial arch

Front 90

The pharyngeal constrictors, cricothyroid, and levator veli palatini are derived from the ___ branchial ___.

Back 90

fourth branchial arch

Front 91

The intrinsic muscles of the larynx (except cricothyroid) are derived from the ___ branchial ___.

Back 91

sixth branchial arch

Front 92

Cleft lip results from failure of fusion of the...

Back 92

maxillary process and medial nasal process

Front 93

Cleft palate results from failure of fusion of the...

Back 93

lateral palatine process, nasal septum, and/or median palatine process

Front 94

Persistence of herniation of intestine into umbilical cord (covered by peritoneum) =

Back 94

omphalocele

Front 95

Extrusion of intestines through the abdominal folds =

Back 95

gastroschisis

Front 96

Omphalocele occurs around week ___

Back 96

week 10, when the guts are supposed to go back in

Front 97

What part of the pancreas comes from the ventral pancreatic bud?

Back 97

the uncinate process

Front 98

What happens to the pronephros?

Back 98

It degenerates and does not contribute to the fetus at birth.

Front 99

What happens to the mesonephros?

Back 99

It serves as the interim kidney for the first trimester before transforming into the internal male repdroductive organs.

Front 100

What happens to the metanephros?

Back 100

It forms the permanent kidney. Develops from weeks 5-36, and takes over function from the mesonephros at ~week 12.

Front 101

Horseshoe kidney is associated with what chromosomal abnormality?

Back 101

Turner syndrome

Front 102

The internal male reproductive organs derive from the...

Back 102

mesonephric (Wolffian) ducts

Front 103

The internal female reproductive organs derive from the...

Back 103

paramesonephric (Mullerian) ducts

Front 104

The genital tubercle becomes what in males? In females?

Back 104

Males: glans penis, corpera cavernosa and spongiosa. Females: glans clitoris, vestibular bulbs.

Front 105

What gives rise to the prostate and bulbourethral glands of Cowper?

Back 105

the urogenital sinus

Front 106

What gives rise to the Skene's (urethral, paraurethral) and Bartholin's (greater vestibular) glands?

Back 106

the urogenital sinus

Front 107

The urogenital folds give rise to what in the male? Female?

Back 107

Male: ventral shaft of penis and penile urethra. Female: labia minora.

Front 108

In females, the gubernaculum becomes what?

Back 108

the ovarian ligament and round ligaments of the uterus

Front 109

In males, the gubernaculum becomes what?

Back 109

It remains, and anchors the testes in the scrotum.

Front 110

What happens to the processus vaginalis in males? Females?

Back 110

Males: becomes the tunica vaginalis, and causes indirect inguinal hernia if patent. In females, it is obliterated.