Craniofacial Embryology Flashcards

1
Q

when do head and neck develop

A

weeks 4-8

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2
Q

what embryonic structure do the head and neck develop from

A

pharyngeal apparatus

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3
Q

pharyngeal apparatus is sometimes called

A

branchial apparatus

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4
Q

3 components of pharyngeal apparatus

A

clefts, arches, pouches

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5
Q

on what day do the 5 pairs of pharyngeal arches start to form

A

22

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6
Q

what separates the pharyngeal arches externally

A

clefts

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7
Q

what are pharyngeal clefts composed of

A

ectoderm

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8
Q

what separates pharyngeal arches internally

A

pouches

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9
Q

what are pharyngeal pouches composed of

A

endoderm

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10
Q

outer covering of pharyngeal arch is composed of

A

ectoderm

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11
Q

inner lining of pharyngeal arch is composed of

A

endoderm

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12
Q

core of pharyngeal arch is composed of

A

mesenchyme derived from mesoderm and neural crest

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13
Q

what elements of pharyngeal arch are derived from neural crest

A

cartilage, connective tissue, and arch-associated cranial nerve

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14
Q

what elements of pharyngeal arch are derived from mesoderm

A

skeletal muscle and an aortic arch artery

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15
Q

2 components of first pharyngeal arch

A

maxillary process, mandibular process

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16
Q

maxillary process becomes

A

maxilla, zygomatic bones

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17
Q

mandibular process becomes

A

mandible, middle ear structures (incus, malleus)

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18
Q

incus and malleus are derived from what embryonic structure

A

Meckel’s cartilage

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19
Q

what skeletal muscles are derived from first pharyngeal arch

A

muscles of mastication, anterior digastric, mylohyoid, tensory tympani, anterior 2/3 of tongue

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20
Q

what cranial nerve is associated with first pharyngeal arch

A

mandibular and maxillary divisions of trigeminal nerve

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21
Q

what artery is associated with first pharyngeal arch

A

portion of maxillary

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22
Q

what embryonic structure is derived from second pharyngeal arch

A

Reichart’s cartilage

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23
Q

What does Reichart’s cartilage give rise to?

A

stapes bone, styloid process of temporal bone, part of the hyoid bone

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24
Q

what skeletal muscles are derived from second pharyngeal arch

A

muscles of facial expression, stapedius, stylohyoid, posterior digastric

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25
Q

what cranial nerve is associated with second pharyngeal arch

A

facial nerve

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26
Q

what embryonic arteries are derived from second pharyngeal arch and what artery does one of them become

A

stapedial and hyoid (becomes branch of internal carotid)

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27
Q

bones formed from third pharyngeal arch

A

part of hyoid

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28
Q

muscles formed from third pharyngeal arch

A

stylopharyngeus

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29
Q

arteries formed from third pharyngeal arch

A

common carotid arteries and proximal internal carotid arteries

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30
Q

cranial nerve associated with third pharyngeal arch

A

glossopharyngeal

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31
Q

4th and 6th pharyngeal arches share what nerve

A

vagus

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32
Q

4th arch is associated with what branch of vagus nerve

A

superior laryngeal

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33
Q

6th arch is associated with what branch of vagus nerve

A

recurrent laryngeal

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34
Q

4th and 6th arches fuse to form

A

laryngeal cartilages and muscles

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35
Q

list the laryngeal cartilages

A

thyroid, cricoid, arytenoid, corniculate, cuneiform

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36
Q

4th arch forms what muscles

A

cricothyroid, levator palatini, pharyngeal constrictors

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37
Q

6th arch forms what muscles

A

intrinsic muscles of larynx except cricothyroid

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38
Q

4th arch artery becomes

A

arch of aorta on left and proximal right subclavian

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39
Q

6th arch artery becomes

A

proximal pulmonary arteries and ductus arteriosus

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40
Q

derivatives of first pharyngeal cleft

A

external auditory meatus, external part of tympanic membrane

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41
Q

derivatives of first pharyngeal pouch

A

internal part of tympanic membrane, tympanic cavity, and eustachian tube

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42
Q

derivatives of second pouch

A

palatine tonsil

43
Q

derivatives of third pouch

A

inferior parathyroid glands and thymus

44
Q

derivatives of fourth pouch

A

superior parathyroid and ultimobranchial body

45
Q

derivatives of ultimobranchial body

A

C cells of thyroid

46
Q

how is the cervical sinus formed

A

the 2nd arch grows over and fuses with 3rd and 4th arches, the cervical sinus was the 2nd-4th clefts

47
Q

what happens if the 2nd-4th arches do not fuse completely

A

a cervical fistula or cervical cyst

48
Q

location of cervical fistulas or cysts

A

lateral, anterior to SCM, below angle of mandible

49
Q

other characteristics of cervical fistulas or cysts

A

are immobile and can occur on one or both sides

50
Q

tongue mucosa develops from

A

floor endoderm lining pharyngeal arches

51
Q

anterior 2/3 of tongue formed by

A

1st and 2nd pouches

52
Q

posterior 2/3 of tongue formed by

A

3rd and 4th pouches

53
Q

thyroid gland is developed from

A

floor endoderm of pharynx

54
Q

what is thyroglossal duct

A

a duct connecting thyroid with pharynx that breaks down

55
Q

former site of thyroglossal duct in adults

A

foramen cecum

56
Q

remnants of thyroglossal duct may persist as

A

pyramidal lobe of thyroid or fibrous strand of tissue

57
Q

thyroglossal duct cysts present as

A

midline neck mass, painless, mobile

58
Q

ectopic thyroid tissue may be found

A

along its path of descent

59
Q

most common place for ectopic thyroid tissue to be found

A

base of tongue

60
Q

face develops from

A

frontonasal process and first arch (maxillary and mandibular processes)

61
Q

how is the primary palate formed

A

a fusion between maxillary and lateral nasal processes

62
Q

how are lower lip and jaw formed

A

mandibular processes fuse in the midline

63
Q

junction between primary and secondary palate is called

A

incisive foramen

64
Q

cleft lip results from

A

incomplete fusion of maxillary process with medial nasal process

65
Q

cleft palate results from

A

incomplete fusion of palatal shelves

66
Q

when is the face formed

A

week 10

67
Q

what part of the eye derives from neuroectoderm

A

optic cup

68
Q

what part of the eye derives from ectoderm

A

lens

69
Q

optic vesicles derive from

A

neural tube

70
Q

lens develops from

A

lens placode, thickening of ectoderm

71
Q

optic cup becomes

A

retina, iris

72
Q

what is the choroid of the eye

A

layer of blood vessels and connective tissue between sclera and retina

73
Q

choroid of the eye is an extension of

A

pia mater and arachnoid

74
Q

what is the sclera

A

tough, fibrous white outer wall of the eye, continuation of dura mater

75
Q

eyelids develop as

A

ectodermal folds with a mesenchymal core from the first arch

76
Q

what is a coloboma

A

optic fissure fails to close, leaving a gap in eye structures, can be throughout the eye or localized

77
Q

what genetic mutations can congenital cataracts develop from

A

CRYSTALLIN, gap junction proteins, transcription factors

78
Q

causes of congenital cataracts

A

genetic mutations, metabolic disorders (galactosemia), congenital infections (rubella)

79
Q

what is a detached retina

A

neural retina detaches from pigmented retina

80
Q

detached retina causes

A

congenital or head trauma

81
Q

external auditory meatus develops from

A

1st cleft

82
Q

pinna/auricle develops from

A

1st/2nd arches

83
Q

auditory ossicles develop from

A

1st/2nd arches

84
Q

tympanic cavity and auditory tubes develop from

A

1st pouch

85
Q

inner ear develops from

A

ectoderm of otic placode

86
Q

what are auricular hillocks

A

proliferating ectoderm and underlying mesenchyme of 1st and 2nd arches that give rise to auricle

87
Q

auricle develops when

A

5th week

88
Q

what is conductive hearing loss

A

impaired conduction of sound to inner ear due to structural abnormalities of external ear (auricle) or middle ear

89
Q

what is microtia

A

small auricle due to suppressed growth of hillocks

90
Q

what is anotia

A

lack of auricle due to suppressed growth of hillocks

91
Q

what is macrotia

A

large auricle due to overgrowth of hillocks

92
Q

preauricular tags or pits are caused by

A

accessory hillocks

93
Q

defects of external auditory meatus include

A

atresia and stenosis

94
Q

microtia is associated with what genetic disorders

A

bronchio-oto-renal (BOR), CHARGE, Treacher Collins, trisomy 21 and 18

95
Q

microtia is associated with what teratogens

A

alcohol, retinoic acid

96
Q

macrotia is associated with

A

Fragile X syndrome, the most common cause of mental retardation in males

97
Q

middle ear defects develop from

A

defects with malleus, incus, stapes

98
Q

middle ear defects are associated with

A

skeletal dysplasias (achondroplasia, osteogenesis imperfecta), BOR, Treacher-Collins, OAVS

99
Q

inner ear develops from

A

otic vesicle which derives from ectodermal otic placode

100
Q

sensory ganglia of vestibulocochlear nerve develops from

A

otic placode

101
Q

sensorineural hearing loss can result from

A

defects in inner ear, vestibulocochlear nerve, auditory regions of brain

102
Q

about half of all hearing loss has what cause

A

genetic

103
Q

in utero viral infections associated with hearing loss

A

cytomegalovirus, rubella

104
Q

teratogen associated with hearing loss

A

aminoglycoside antibiotics (gentamycin, tobramycin)