Embryology Flashcards

1
Q

What do the pharyngeal arches develop into?

A

much of the face and neck

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2
Q

When do the pharyngeal arches develop?

A

weeks 4 and 5

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3
Q

What are the pharyngeal arches in humans?

A

arches 1,2,3,4 and 6

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4
Q

In what sequence do the pharyngeal arches develop?

A

cranial-caudal

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5
Q

Why don’t you have all the arches present at one time?

A

as they develop in a cranial-caudal sequence, by the time 4 and 6 are developing, 1 will have regressed

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6
Q

What does each pharyngeal arch consist of?

A

core of mesenchyme; neural crest cels; cranial nerve component; artery

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7
Q

What does the core of mesenchyme develop into?

A

musculature of face and neck

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8
Q

What do the neural crest cells develop into?

A

skeletal components of the face

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9
Q

What are the arches separated externally by?

A

deep pharyngeal clefts

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10
Q

What are the arches separated internally by?

A

pharyngeal pouches

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11
Q

What is the lining of the pharyngeal cleft?

A

ectoderm

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12
Q

What is the lining of the pharyngeal pouches?

A

endoderm

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13
Q

What nerve is associated with the 1st arch?

A

maxillary and mandibular divisions of trigeminal

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14
Q

What nerve is associated with the 2nd arch?

A

facial nerve

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15
Q

What nerve is associated with the 3rd arch?

A

glossopharyngeal (9)

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16
Q

What nerve is associated with arches 4 and 6?

A

vagus

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17
Q

What branch of the vagus is associated with arch4?

A

superior laryngeal

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18
Q

What branch is associated with arch 6?

A

recurrent laryngeal

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19
Q

What are the 2 skeletal components of the 1st arch?

A

maxillary process and mandibular process

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20
Q

What develops from the maxiallry process of the 1st arch?

A

maxilla; zygomatic and part of temporal bone

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21
Q

What develops from the mandibular process of the 1st arch?

A

incus; malleus and mandible

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22
Q

What type of cartilage is found within the mandibular process?

A

Meckel’s cartilage- developing type of cartilage that the mandible develops alongside

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23
Q

What are the muscles formed from arch1?

A

muscles of mastication; anterior belly of digastric; mylohyoid; tensor tympani and tensor palatini

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24
Q

What does the mylohyoid form most of?

A

floor of mouth

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25
Q

What nerve supplies the msucles from arch 1?

A

V3

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26
Q

What are the skeletal components of the 2nd arch?

A

stapes; process of temporal bone and stylohyoid ligamnet; lesser horn and upper parto f body of hyoid

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27
Q

What are the muscles formed from arch 2?

A

muscles of facial expression; stapedius; stylohyoid; posterior belly of digastric and auricular muscles

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28
Q

What are the auricular muscles used for?

A

moving the ears- not really used in humans

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29
Q

What nerve supplies the muscles of arch 2?

A

facial nerve

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30
Q

What is the skeletal component of arch 3?

A

greater horn and lower part of body of hyoid

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31
Q

What muscle is formed from arch 3?

A

stylopharyngeus

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32
Q

What is the skeletal component of arches 4 and 6?

A

laryngeal cartilages eg thyroid and cricoid cartilages

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33
Q

What are the muscles of arch 4?

A

cricothyroid; levator palatini; pharyngeal constrictors

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34
Q

What nerve supplies the msucles of arch 4?

A

vagus- superior laryngeal; pharngeal plexus

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35
Q

What are the muscles formed by arch 6?

A

intrinsic laryngeal

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36
Q

What nerve supplesi the intrinsic laryngeal muscle?

A

recurrent laryngeal nerve

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37
Q

What does the 1st cleft develop into?

A

external auditory meatus

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38
Q

What do the 2nd-4th clefts devlop into?

A

lose contact with outside and form the cervical sinus which usually disappears

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39
Q

What develops from the 1st pouch?

A

middle ear; eustachian tube; tympanic membrane

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40
Q

What develops from the 2nd pouch?

A

palatine tonsil- will be invaded by lots of lymphoid tissue

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41
Q

What develops from the 3rd pouch?

A

inferior parathyroid gland; thymus

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42
Q

What develops from the 4th pouch?

A

superior parathyroid glands; ultimobranchial body (c cells of thyroid gland)

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43
Q

What do C cells produce?

A

calcitonin

44
Q

What does the thyroid develop from?

A

a proliferation of the tongue

45
Q

How does the thyroid descend down into the neck?

A

anterior to the gut tube

46
Q

How do the inferior parathyroid glands migrate from above the superior glands to their place?

A

the thymus migrates, pulling the inferior parathyroid glands down with it, then pulls away from the thymus when passing the thyroid

47
Q

What is an otic placode?

A

thickening of the ectoderm which give rise to structures of the ear- one on each side

48
Q

What do the otic placodes overly?

A

the hindbrain

49
Q

What happens to the otic placodes?

A

thye invaginate and form a pit and then a vesicle

50
Q

What do the otic vesicles give rise to?

A

inner ear

51
Q

What is the statoacoustic ganglion and how does it relate the forming of otic vesicles?

A

The statoacoustic ganglion give rise to sensory cells in the ear, breaks away from the placode as the vesicle develops

52
Q

What does the utricular portion of the otic vesicle give?

A

semicircular canals

53
Q

What does the saccular portion of the otic vescicle give rise to?

A

cochlea

54
Q

What connects the utricular and saccular portions of the vesicle?

A

utriculosaccular duct

55
Q

How do the semicircular canals develop?

A

there are flattened outpocketings of utricular part, the cnetral part of these walls appose each other and break down, leaving tubes aroudn the outside

56
Q

What is the dilated end of the semicircular canals called?

A

crus ampullare

57
Q

What is the non-dilated end of the semicircular canals called?

A

crus-nonampullare

58
Q

What is found within the ampullae?

A

crista ampullaris which contains sensory cells for balance and vestibular fibres of CN8

59
Q

When does the cochlear duct grow?

A

between weeks 6 and 8

60
Q

What happens to the surrounding mesenchyme in the cochlea between weeks 6-8?

A

becomes cartilaginous and ossifies nad forms cavities

61
Q

How does the organ of Corti develop?

A

develops from the cochlear duct, develops tectorial membrane and then 3 rows of outer hair cells and 1 row of innter hair cells

62
Q

How is the tectorial membrane involved in hearing?

A

movement of hair on the membrane creates APs

63
Q

What does the middle ear develop from ?

A

1st pharyngeal pouch

64
Q

What is the mesenchymal condensation formed from?

A

1st and 2nd pouches

65
Q

What does the 1st pouch develop into?

A

develops a small swelling to form the primitive tympanic cavity

66
Q

What happens with the primitive tympanic cavity and the mesenchymal condensation?

A

3 ossicles develop in the condensation as the mesenchyme breaks down, the cavity encroaches upon these

67
Q

What coats the 3 ossiclaes of the middle ear?

A

endoderm- ligaments attaching the bones in place

68
Q

What does the EAM develop from?

A

1st pharyngeal cleft

69
Q

What do the epithelial cells at the 1st phayngeal cleft develop into?

A

Meatal plug which then contributes the the eardrum

70
Q

How is the auricle formed?

A

6 mesenchymal proliferations from arch 1 and 2 which surrpound the 1st pharyngeal cleft in auricular hillocks.

71
Q

where do the the auricles initially develop and why do they move?

A

in the neck, move due to the devleopment of the mandible

72
Q

What facial structures does arch1 give rise to?

A

maxilla, mandible, zygomatic and temporal squamous bones; muscles of mastication

73
Q

What facial structures does arch 2 give rise to?

A

muscles of facial expression

74
Q

What gives rise to the upper and mid-facial features?

A

proliferating mesechyme associated with the forebrain

75
Q

What cells give rise to the skeletal components?

A

neural crests

76
Q

Waht nerve is associated with arch1?

A

V

77
Q

What nerve is associated with arch2?

A

VII

78
Q

What nerve is associated with arch 3?

A

IX

79
Q

Waht nerve is assocaited with arches 4 and 6?

A

vagus

80
Q

What are the 5 facial swellings present from week 4?

A

frontonasal prominence; 2 maxillary prominences and 2 mandibular prominences

81
Q

What is the future opneing of the mouth called?

A

stomodeum

82
Q

How do the facial swelling develop?

A

aroun the stomodeum

83
Q

What is present laterally in the frontonasal prominces?

A

nasal placodes

84
Q

What are the 4 nasal swellings that develop in the frontonasal prominence in week 5?

A

2 medial and 2 lateral nasal swellings

85
Q

How do the nasal swellings develop?

A

the nasal placodes begin to invaginate, tissue surrounding invagination begins to swell

86
Q

Where does the nasolacrimal groove lie?

A

between the maxillary prominence and the lateral nasal prominence

87
Q

Where do the eyes develop in relation to the nasal swellings?

A

lateral

88
Q

How do the medial nasal swelling and maxillary prominences join together?

A

maxillary prominence puts pressure on nasal wellings moving them medially, as this happens the medial swelling develops downwards to medial edge of maxillary prominence to join together

89
Q

Hwo does the nasolacrimal duct form?

A

ectoderm proliferates to form a solic epithelial cord which detaches from the ectoderm and canalises to form the duct

90
Q

What forms the upper lip?

A

2 medial nasal prominences and 2 maxillary promences

91
Q

What forms the lower lip?

A

mandibular prominences

92
Q

What forms the bridge and nasal septum of the nose?

A

frontonasal prominence

93
Q

What forms the crest and tip of the nose?

A

medial nasal prominences

94
Q

What forms the alae of the nose?

A

lateral nasal prominences

95
Q

What gives the intermaxillary segment?

A

fusion of medial nasal promiences

96
Q

What is the intermaxillary segmnet?

A

primary palate

97
Q

What does the labial protion of the intermaxillary segment give rise to?

A

philtrum of upper lip

98
Q

What does the upper jaw of the intermaxillary segment give rise to?

A

carries 4 incisors

99
Q

What does the palatal component of the intermaxillary segment give rise to?

A

forms primary palate

100
Q

What are the palatine shelves derived from?

A

maxillary promineneces

101
Q

What happens during week 7 of the devleopment of the secondary palate?

A

shelves ascend to horizontal position as tongue moves down (were on either side of tongue); fuse together to form secondary palate and fuse with primary palate anteriorly

102
Q

What is found at the meeting of the primary and the 2 sides of the secondary palates?

A

incisive foramen

103
Q

What happens during week 6 with the nasal cavities?

A

nasal pits deepen and penetrate into underlying mesenchyme

104
Q

What separates the nasal pits from the oral cavity during week 6?

A

oronasal membrane

105
Q

What happens to the oronasal membrae and what does this result in?

A

breaks down so the oral and nasal cavities are one

106
Q

What is the communication between the nasal and oral cavities called?

A

primitive choanae

107
Q

When does the definitive choanae arise?

A

with the secondary palate- so communication is behind that