Introductory Embryology, Oral-Facial Development and Associated Developmental Abnormalities Flashcards

1
Q

What are the stages of human development?

A

-Proliferation period (0-3 weeks)
-embryonic period (3-8 weeks)
-fetal development period (9 weeks to term)

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2
Q

What forms after an ovum is fertilized?

A

zygote

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3
Q

What does mitotic cleavage of a zygote form?

A

blastomere

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4
Q

What is the stage of >32 blastomeres called?

A

morula

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5
Q

What happens at the 64 cell stage?

A

morula develops an internal blastocytstic cavity and becomes a blastocyst

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6
Q

What is a cyst?

A

a mass lined with usually epithelial tissue with a hollow cavity
(can be fluid filled)

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7
Q

What is an embryoblast ?

A

cell stage in development after the blastocyst develops an inner cell mass

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8
Q

When does implantation of embryoblast occur?

A

starting at day 4 and usually done by day 10

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9
Q

What are syncytiotrophoblasts?

A

finger like projections that help the embryoblast implant into the wall of the uterus

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10
Q

What is the bilaminar embryonic disc?

A

two layers of cells that form in the inner cell mass

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11
Q

When does the bilaminar embryonic disc form?

A

when the embryoblast starts getting engulfed into the uterine wall

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12
Q

What does the outer cell mass become?

A

cytotrophoblast and syntrophoblast layers
(precursors to the placenta)

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13
Q

What does the epiblast layer of the bilaminar embryonic disc become?

A

ectoderm and mesoderm

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14
Q

What does the hypoblast layer of the bliaminar disc become?

A

endoderm

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15
Q

What is the Heuser’s membrane?

A

the internal lining of the blastocyst cavity

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16
Q

What is the blastocyst cavity become?

A

yolk sac

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17
Q

What is the third cavity that forms during development?

A

chorionic cavity

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18
Q

What are the three distinct embryonic germ layers?

A

endoderm
mesoderm
ectoderm

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19
Q

What is formed during the 3rd week of development from the bilaminar embryonic disc?

A

primitive streak
notochord
neural tube

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20
Q

How is the notochord formed?

A

pre-notochordal cells invaginate within the primitive node and migrate toward the cephalad until the reach the prechordal plate
-they detach themselves from the ectodermal layer to line within the mesoderm forming the notochord

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21
Q

What is the order of steps to make the notochord?

A

primitive node -> notochordal process -> notochord

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22
Q

What is the function of the notochord?

A

functions as a primitive skeletal support of the embryo around which the axial skeleton forms later

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23
Q

What does the notochord induce the formation of?

A

the somites
-precursors of the vertebral column, ribs, associated back muscles, and overlying dermis

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24
Q

What are the three types of mesoderm?

A

-paraxial
-intermediate
-lateral plate

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25
Q

What are the two types of lateral plate mesoderm?

A

-parietal
-visceral

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26
Q

What does the paraxial mesoderm form?

A

somites

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27
Q

What does the intermediate mesoderm form?

A

the urogenital system

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28
Q

What does the parietal segment of the lateral plate mesoderm form?

A

mesothelial (serous) membranes that cover the peritoneal, pleural, and pericardial cavities

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29
Q

What does the visceral segment of the lateral plate mesoderm form?

A

the thin serous membranes that cover individual organs, stomach, pancreas, spleen, and other organs

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30
Q

What are the derivatives of ectoderm?

A

-epidermis, hair, and nails
-epithelium of the oral and nasal cavities and paranasal sinuses
-salivary and endocrine glands
-nervous system
-tooth enamel

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31
Q

What are the derivatives of the endoderm?

A

GI tract epithelium and associated glands

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32
Q

What is spina bifida?

A

developmental defect that occurs when the neural tube does not close properly
-due to folic acid deficiency

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33
Q

What is meningocele?

A

extrusion of dura and arachnoid mater

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34
Q

What is meningomyelocele?

A

extrusion of neural tissue plus all three meninges

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35
Q

What is meningoencephalocele?

A

extrusion of a ventricular cistern plus neural tissue

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36
Q

What is anencephaly?

A

fatal defect characteristics by lack of development of the cranium and brain

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37
Q

What are other names for neural crest cells?

A

ectomesenchyme and neuroectoderm

38
Q

What are some of the things that cranial neural crest cells form ?

A

-odontoblasts
-truncocoronal septum
-pharnygeal arch and cartilage
-dermis and epidermis of the head and neck

39
Q

What are some things that spinal neural crest cells form?

A

-preaortic ganglia
-adrenal medulla
-dorsal root ganglia
-chain ganglia

40
Q

What are some things that are formed from both cranial and spinal neural crest cells?

A

-schwann cells
-glial cells
-arachnoid and pia mater
-enteric ganglia

41
Q

When do the pharyngeal arches begin forming?

A

day 28 of development

42
Q

What are associated with each level of pharyngeal arches?

A

blood vessel, cranial nerves, and cartilage

43
Q

What does the 1st branchial groove form?

A

external auditory canal

44
Q

What does the 1st branchial pouch form?

A

eustachian tube

45
Q

What does the 2nd branchial pouch form?

A

palatine tonsils

46
Q

What does the 3rd branchial pouch form?

A

inferior parathyroids/thymus

47
Q

What does the 4th branchial pouch form?

A

superior parathyroids/ultimobranchial body

48
Q

What happens to the relative size of the fetal head during development?

A

the head stays around the same size but the body gets larger
-means the percentage of the fetus that is head gets smaller

49
Q

What are the four processes of the face that start lateral and move toward the medial to form the face?

A

-mandibular process
-maxillary process
-lateral nasal process
-median nasal process

50
Q

What is the remanent of the face of the lateral processes coming together?

A

the filtrum of the lip

51
Q

What can happen if the processes do not meet properly?

A

cleft lip or palate

52
Q

When does fusion of the maxillary and medial nasal processes usually occur?

A

5-6 weeks gestation

53
Q

when does fusion of the palatine shelves occur?

A

begin during the 8th week and is completed in the 12th week

54
Q

What percentage of clefts are combined cleft lip/palate?

A

45%

55
Q

What percentage of clefts are just cleft palate?

A

30%

56
Q

What percentage of clefts are just cleft lip?

A

25%

57
Q

Incidence of cleft lip/palate in Chinese, Japanese, and Native American populations

A

1 in 500

58
Q

Incidence of cleft lip/palate in Caucasian populations

A

1 in 700

59
Q

Incidence of cleft lip/palate in African American populations

A

1 in 500

60
Q

Incidence of cleft lip/palate in all populations

A

1 in 2500

61
Q

Is there a genetic aspect of cleft lip/palate?

A

yes sort of
-if you have one child with cleft lip/palate, there is a 40% chance of having a second child with it

62
Q

What are some drugs that can cause cleft lip/palate ?

A

ethanol, tetracycline, dilantin, lithium, methotrexate, warfarin, thalidomide, androgens, progesterone, and retinoic acid

63
Q

What are some chemicals that can cause cleft lip/palate?

A

methylmercrury, polychlorinated biphenyls

64
Q

Can radiation cause cleft lip/palate?

A

yes

65
Q

Where can a nasopalatine duct cyst form?

A

at the fusion between palatine shelves and primary plate

66
Q

Where do lateral cervical cyst/branchial fistuals form?

A

along the line of the sternocleidomastiod muscle

67
Q

What pharyngeal arches help to form the tongue?

A

1- forms the anterior part of the tongue and contributes CN 5
2- provides some innervation
3 and 4- both help to form the posterior tongue

68
Q

What is the intermediate and adult structure the come form the branchial arch 1?

A

intermediate
-median tongue bud
-foramen cecum
-lateral lingual swellings
adult
-overgrown my lateral lingual swellings
-origin of the thyroid ectoderm
-anterior 2/3 of tongue

69
Q

What is the intermediate and adult structure the come form the branchial arch 2?

A

intermediate
-copula/tuberculim impar
adult
-overgrown by the hypobranchial eminence

70
Q

What is the intermediate and adult structure the come form the branchial arch 3?

A

intermediate
-hypobranchial eminence
adult
-posterior 1/3 of tongue

71
Q

What is the intermediate and adult structure the come form the branchial arch 4?

A

intermediate
-minor contributions to the hypobranchial eminence
adult
-none

72
Q

What cranial nerve innervates branchial arch 1?

A

CN V (trigeminal)

73
Q

What cranial nerve innervates branchial arch 2?

A

CN VII (facial)

74
Q

What cranial nerve innervates branchial arch 3?

A

CN IX (glossopharyngeal)

75
Q

What cranial nerve innervates branchial arch 4?

A

CNX (vagus)

76
Q

What cranial nerve innervates branchial arch 6?

A

CN XII (hypoglossal)

77
Q

What does the trigeminal nerve do for the tongue?

A

sensory to the anterior 2/3

78
Q

What does the facial nerve do for the tongue?

A

special sensory (taste) to anterior 2/3 via the chorda tympani branch

79
Q

What does the glossopharyngeal nerve do for the tongue?

A

sensory to the posterior 1/3

80
Q

What does the vagus nerve do for the tongue?

A

sensory to the extreme posterior 1/3 via the superior laryngeal branch

81
Q

What does the hypoglossal nerve do for the tongue?

A

motor to all of the tongue muscles

82
Q

What is the median rhomboid glottitis?

A

was thought to present a portion of the tuberculum impar (branchial arch II) that persists, but is now considered to be a result of a fungal infection

83
Q

How does a thyroglossal duct cyst form?

A

failure of thyroglossal duct to involute

84
Q

Where does the thyroid start forming?

A

near the foramen cecum of the tongue
-must move inferiorly past the epiglottis, hyoid bone, thyroid cartilage, and the cricoid cartilage to make it to the correct place

85
Q

What is a ectopic lingual thyroid?

A

when the thyroid does not move inferiorly and remains on the posterior part of the tongue

86
Q

What cartilages forms from the first pharyngeal arch?

A

Meckel’s cartilage
Mandible
maleus
incus

87
Q

What cartilage and bone forms from the second pharyngeal arch?

A

reichart’s cartilage
stapes
styloid process
stylohyoid ligament
lesser horn of hyoid

88
Q

What cartilage and bone forms from the third pharyngeal arch?

A

greater horn of hyoid

89
Q

What cartilage and bone forms from the fourth pharyngeal arch?

A

thyroid cartilage

90
Q

What are the segments that are combined to form the ear?

A

there are 6 auricular hillocks that come together to form the ear
-sometimes there are more than 6 or less than 6 depending on formation