Embryology Flashcards
(155 cards)
1
Q
Deep midline gash that becomes the oral cavity
A
Stomodeum
2
Q
Bilateral growth of embryonic tissue in the ventro-lateral region of the head
- 5 pairs of pharyngeal arches form in cranial to caudal sequence
A
Pharyngeal Apparatus
3
Q
Pharyngeal arches are separated by ___________ on the outside
A
pharyngeal grooves/clefts
4
Q
Direction of formation of pharyngeal arches
A
cranial to caudal
5
Q
Pharyngeal arch formation is primarily driven by __________________
A
the migration and proliferation of neural crest
6
Q
The two sub-prominences of the first pharyngeal arch
A
maxillary and mandibular prominence
7
Q
Most of the pharyngeal clefts close/smooth over in order to provide a smooth neckline; however, the first pharyngeal cleft becomes the ___________
A
external auditory meatus
8
Q
The oralpharyngeal membrane is ____________ to the stomodeum
A
posterior
9
Q
The external auditory meatus is left over from which pharyngeal cleft?
A
first pharyngeal cleft
10
Q
Are the pharyngeal clefts numbered according to the arches above or below them
A
above
11
Q
Around week _________ the oralpharyngeal membrane perforates to allow for the tongue and other structures to develop into the primitive oral cavity
A
3 to 4
12
Q
The pharyngeal arches mainly arise from proliferating / migrating neural crest cells.
How many distinct streaks migrate and in which direction do the travel?
A
5 streaks
Migrating ventrally
13
Q
Pharyngeal arch outside covering?
A
Ectoderm
14
Q
Pharyngeal arch inside lining
A
Endoderm
- Note: arch 1 is covered mostly by ectoderm on the inside -> oral ectoderm
15
Q
Core of each arch - composition
A
mesenchyme
16
Q
The core of pharyngeal arch is mesenchyme. What makes up the major component of the mesenchyme
A
neural crest
17
Q
Neural crest cells make up the majority of the mesenchyme of the core of the pharyngeal arch - what structures do these neural crest cell give rise to?
A
Cartilage and Bone
18
Q
In addition to neural crest cells, what else comprises the core of pharyngeal arches?
A
Mesoderm (paraxial) –> skeletal muscles
Nerve (V, VII, IX, X)
Blood vessel
19
Q
Skeletal muscle of the face comes from?
A
Paraxial plate mesoderm
mesoderm balls up into somites which differentiate into myotomes - myotomes then migrate to provide skeletal muscle :
20
Q
The first arch is subdivided into the ___________ prominence cranially, and into the __________ prominence caudally
A
cranially - maxillary
caudally - mandibular
21
Q
First arch
Cranial Nerve ____
A
V
22
Q
First arch - maxillary prominence
Cranial Nerve ___
A
V2 (maxillary)
23
Q
First arch - mandibular prominence
Cranial Nerve ___
A
V3 (mandibular)
24
Q
The maxillary nerve is associated with which pharyngeal arch
A
1
25
The mandibular nerve is associated with which pharyngeal arch
1
26
The facial nerve is associated with which pharyngeal arch
2
27
The vagus nerve is associated with which pharyngeal arch
4/6
28
The glossopharyngeal nerve is associated with which pharyngeal arch?
3
29
Do pharyngeal arches receive a common blood vessel supply?
No... each pharyngeal arch has its own blood vessel supply
30
All of the myotomes of 1st pharyngeal arch - mandibular prominence have ________ nerve innervation
mandibular (V3)
31
All of the myotomes of 1st pharyngeal arch - maxillary prominence have ________ nerve innervation
maxillary (V2)
32
All of the myotomes of the 3rd pharyngeal arch have _______ nerve innervation
glossopharyngeal
33
All of the myotomes of the 4/6 pharyngeal arch have _________ nerve innervation
vagus
34
All of the myotomes of the 2nd pharyngeal arch have ________ nerve innervation
facial
35
Mesenchyme (embryonic CT) can come from ectoderm, endoderm, neural crest...
In the pharyngeal arches, which germ layer comprises the mesenchyme
neural crest
36
We retain the first pharyngeal membrane as __________
the tympanic membrane
37
Separates pharyngeal arches from the outside
pharyngeal groove / cleft
38
Pharyngeal groove / cleft is lined by?
ectoderm
39
Separates pharyngeal arches from the inside
pharyngeal pouch
40
pharyngeal pouches are lined by
endoderm
41
Where ectoderm and endoderm come together at pharyngeal cleft/grooves
pharyngeal membrane
42
Pharyngeal arch 1
- -> Neural crest derivatives
- ----> Maxillary Prominence
Maxillary bone
| Zygomatic and squamous portions of temporal bone
43
Pharyngeal arch 1
- -> Neural crest derivatives
- ----> Mandibular Prominence
```
Meckel's cartilage (embyro)
Mandible
Malleus
Incus
Anterior ligament of Malleus
```
44
Pharyngeal arch 2
| --> Neural crest derivatives
```
Reichert Cartilage (embryo)
Lesser cornu of hyoid (superior hyoid)
Stylohyoid ligament
Styloid process
Stapes
```
45
Pharyngeal arch 2 is associated with which cranial nerve?
Facial (VII)
46
Pharyngeal arch 3
| --> Neural crest derivatives
Body of hyoid
Greater Cornu of Hyoid
(Collectively inferior hyoid)
47
Pharyngeal arch 4/6
Thyroid and Cricoid cartilage of larynx (laryngeal cartilages)
48
Arches develop from _______ to _________ direction
cranial to caudal
49
Pharyngeal arch 1
| --> mesoderm derivatives
```
Muscles of mastication:
- temporalis
- masseter
- medial pterygoid
- lateral pterygoid
mylohyoid
ant. belly digastric
tensor tympani
```
50
Innervation of first pharyngeal arch (cranial nerve)?
trigeminal
51
Pharyngeal arch 2
| --> mesoderm derivatives
muscles of facial expression
stylohyoid
posterior belly digastric
52
Innervation of the second pharyngeal arch? (CN)
Facial (VII)
53
Pharyngeal arch 3
| --> mesoderm derivatives
stylopharyngeus
54
Innervation of third pharyngeal arch? (CN)
glossopharyngeal
55
Pharyngeal arch 4&6
| --> mesoderm derivatives
pharyngeal constrictors
soft palate muscles
laryngeal muscles
56
Innervation of 4/6 pharyngeal arch? (CN)
vagus
57
Pharyngeal arch 1
| Motor Innervation
Muscles of mastication
ant bell of digastric
tensor tympani
58
Pharyngeal arch 1
| Sensory innervation
somatosensation
- face
- teeth
- anterior 2/3 tongue
- palate
59
Which pharyngeal arch provides taste sensation to anterior 2/3 tongue?
Pharyngeal arch 2
| facial
60
Does pharyngeal arch 2 contribute sensation to tongue?
ONLY special sensory (taste)
NOT somatosensory
(Pharyngeal arch 1 and 3 are responsible for ant 2/3 and post 1/3 of tongue's somatosensation, respectively)
61
Pharyngeal arch 2
| Motor innervation
Muscles of facial expression
Posterior belly digastric
stylohyoid
62
Pharyngeal arch 2
| Sensory innervation
```
special sensory (taste) for anterior 2/3 tongue
NO somatosensory
```
63
Pharyngeal arch 3
| Motor innervation
stylopharyngeus
64
Pharyngeal arch 3
| Sensory innervation
Somatosensory and special sensory (taste)
| posterior 1/3 tongue
65
Pharyngeal arch 4/6
| Motor innervation
Pharyngeal and Laryngeal muscles
| exceptions: tensor veli palatini - 1 and stylopharyngeus -3
66
Review: what gives rise to vertebrae?
sclerotomes from paraxial lateral plate mesoderm
67
Pharyngeal arch 1 - endoderm derivatives
| The first pharyngeal pouch dilates outward to form the ___________ which will give rise to the _____(3)______
tubotympanic recess
Tympanic cavity (middle ear) / Mastoid antrum / Eustachian tube
68
Fate of first pharyngeal groove/cleft
External auditory meatus
69
Fate of first pharyngeal membrane
tympanic membrane
70
Germ cell layer - squamous portion of temporal bone?
Neural crest
71
Structural origin - squamous portion of temporal bone?
first pharyngeal arch - maxillary prominence
72
Structural origin - stapes?
2nd (neural crest)
73
Structural origin - masseter?
1st arch (paraxial mesoderm)
74
Structural origin - orbicularis oculi?
2nd arch (paraxial mesoderm)
75
Structural origin - stapedius
2nd arch (paraxial mesoderm)
76
Structural origin - posterior belly digastric
2nd arch (paraxial mesoderm)
77
Structural origin - anterior belly digastric
1st arch (paraxial mesoderm)
78
The first pharyngeal arch is mainly covered by ectoderm inside, what is the first pharyngeal pouch covered by?
endoderm
79
What gives rise to the eustachian tube and middle ear
tubotympanic recess from the first pharyngeal pouch
80
what gives rise to the external auditory meatus
first pharyngeal groove/cleft
81
what gives rise to the tympanic membrane?
first pharyngeal membrane
82
Pharyngeal pouch 2 - endoderm derivative
palatine tonsil
83
pharyngeal pouch 3 - endoderm derivatives
ventral bud -> thymus
| dorsal bud -> inferior parathyroid glands
84
pharyngeal pouch 3 forms two diverticula, ventral and dorsal; in which direction does the ventral diverticula migrate?
descends down the neckline to infront of the mediastinum - gives rise to thymus
85
pharyngeal pouch 4/6 - endoderm derivatives
ventral bud - ultimopharyngeal body (parafollicular cells in thyroid that -> calcitonin)
dorsal bud - superior parathyroid
86
How does the superior parathyroid gland (dorsal bud 4/6) end up above inferior parathyroid gland (dorsal bud 3)
The developing/migrating thymus (ventral bud 3) drags the developing inferior parathyroid gland (dorsal bud 3) down with it
87
palatine tonsil - derivation?
2nd bud
88
ultimopharyngeal body (thyroid parafollicular cells) - derivation
4th ventral bud
89
inferior parathyroid gland -derivation
3rd dorsal bud
90
superior parathyroid gland - derivation
4th dorsal bud
91
thymus - derivation
3rd ventral bud
92
Pharyngeal groove/cleft transformation
Pharyngeal groove 2-4 coalesce into _____________ as arch 2 and 4 expand and fold towards each other; once the folds fuse, renamed to _________
cervical sinus
| cervical vesicle
93
The cervical vesical - which arose from the fusion of expanding arches 2 and 4 - should eventually degenerate. What is the clinical consequence if it does not?
Cervical (branchial) cyst
94
Cervical cysts present in what location?
anywhere along anterior border of SCM
95
Cervical cyst = persistent ________
cervical vesicle
96
persistent cervical sinus =
cervical sinus
97
Clinical
| Cervical sinuses open to?
either outside environment pharyngeal space (rare)
98
Continuous duct between pharynx and neck surface
cervical fistula
99
What is the difference between cervical sinus and cervical fistula
Cervical fistula is a continuous connection between pharynx and neck - so you can have fluid draining from pharynx to external neck
Cervical sinus does not extend from pharynx to neck - the duct ends in a cleft/pouch
100
Thyroid gland development
- Endoderm between pharyngeal arches ___ and ___ form a thyroid primordium in the midline and invaginate __(direction)_____
1 & 2
| caudally
101
As the thyroid gland grows caudally, it is still open to the pharynx vial the _____________
thyroglossal duct
102
The thyroglossal duct opens into the pharyngeal space at the ___________
foramen cecum
103
Do adults have thyroglossal ducts?
No - it degenerates (wk12) so that there is no longer communication between thyroid and oropharyngeal space
104
Do adults have foramen cecum?
Yes - indentation between anterior and posterior tongue
105
The foramen cecum (remnant) is a reminder that the thyroid developed from the developing _____________
tongue (ectoderm)
106
The thyroglossal duct should degenerate. However, what is the clinical consequence if it does not?
thyroglossal duct cyst
107
Thyroglossal duct cyst is most common at what level?
| What kind of tissue could it contain?
- Level of the hyoid bone (anterior)
| - Could contain ectopic thyroid tissue
108
How can we differentiate thyroglossal duct cysts from cervical cysts?
Thyroglossal duct cysts occur along the anterior neck line
| Cervical cysts occur along the lateral border of the neck
109
Anterior 2/3 tongue - origin?
1st pharyngeal arch
| Ectodermal lining
110
Posterior 1/3 tongue - origin?
3rd and 4th arches
(hypopharyngeal eminence)
Endoderm
111
Development of tongue
| 2nd arch gives rise to?
Copula
(A swelling formed during the early development of the tongue by the medial portions of the second pharyngeal arches; it is overgrown by the hypopharyngeal eminence and is not present in the adult tongue.)
112
In the embryo, a small elevation in the floor of the mouth (from 1st arch); it is overgrown by the lateral lingual swellings and forms a small unrecognizable part of the posterior region of the anterior two thirds of the tongue.
Tuberculum impar
113
Line of fusion between two lingual swellings
median sulcus
114
line of fusion between arch 1 and hypopharyngeal eminence (3+4)
terminal sulcus
115
a median pit on the dorsum of the posterior part of the tongue, from which the limbs of a V-shaped furrow run forward and outward; it is the site of origin of the thyroglossal duct and subsequently, the thyroid gland.
foramen cecum
116
Skeletal muscles of the tongue derive from ______________ somites
occipital
| paraxial mesoderm myotomes
117
Occipital somites migrate into tongue after ______ week
5th
118
Innervation of the tongue
| - anterior 2/3 somatosensory
V2 (mandibular)
| Recall - 1st pharyngeal arch covered by ectoderm of 1st arch
119
Innervation of tongue
| - anterior 2/3 taste
facial (VII)
120
Innervation of tongue
| - posterior 1/3 somatosensory
IX and X
| mainly glossopharyngeal but small amont of vagus near epiglottis
121
Innervation of tongue
| - posterior 1/3 taste
IX (glossopharyngeal)
122
Innervation of tongue
| - Muscle
XII (hypoglossal)
123
Papillae and taste buds develop around week _
8
124
4 types of papillae
filiform
fungiform
folliate
circumvallate
125
While papillae does not have taste buds?
filiform
126
Taste buds transmit taste to CNS via which cranial nerves
VII (facial)
| IX (glossopharyngeal)
127
Do taste buds function in utero?
yes
128
Face begins as five facial primordia around stomodeum 1
2x
2x
1x frontonasal prominence
2x maxillary prominences
2x mandibular prominences
129
Nasal placodes form on __________ prominence(s)?
frontonasal prominence
130
The mesenchyme around nasal placodes proliferates, creating elevations around placodes. In effect, the nasal placodes "sink in" to become ____________, then dilate to become_____________
nasal pits
| nasal sacs
131
elevated regions around nasal pits
nasal prominences
132
Nasal prominences'
| plane of division
medial / lateral
133
What pushes nasal prominences toward midline?
developing maxillary prominences
134
Time frame of medial nasal prominence fusion
WK 6-10
135
Medial nasal prominence gives rise to (2)
```
bridge of nose
intermaxillary segment (philtrum, upper jaw with 4 incisors, primary palate)
```
136
Maxillary prominences fuse with intermaxillary segment to yield:
Ventrally (1)
Dorsally (1)
Ventrally: smooth upper lip
Dorsally: fusion of primary and secondary palate
137
lateral nasal prominences give rise to ______________
alae of nose
138
Lateral nasal prominences fuse with the maxillary prominence. At the site of fusion, the ectoderm thickens into a cord, then "sinks" into underlying mesenchyme - which canalizes to become the _______________
nasolacrimal duct
139
Development of nasal cavity:
____________ fuse at the midline, forming a single nasal cavity separated from the oral cavity by a thin __________ membrane
nasal sacs
| oronasal
140
Rupture of the ___________, dorsal to the primary palate, results in the oral and nasal cavity becoming continuous.
Note: formation of a secondary palate separates nasal and oral cavity
oronasal membrane
141
Differentiated and specialized cranial ectoderm in the nasal cavity =
olfactory epithelium
142
_________ separates the nasal cavity from the oral cavity, preventing aspiration of food
palate
143
soft palate termination =
uvula
144
The primary palate (embryonic division) derives from...
intermaxillary segment (fused medial nasal prominences)
145
The primary palate (embryonic division) gives rise to
anterior, triangular portion of hard palate
146
The secondary palate (embryonic division) derives from...
fusion of palatine shelves that grow from the maxillary prominences
147
The secondary palate (embryonic division) gives rise to...
majority of hard palate and all of soft palate
148
Development of secondary palate:
| palatine shelves form from ____________ internally
maxillary prominences
149
Palatine processes grow in which direction on either side of the developing tongue
caudally
150
```
Development of secondary palate:
Week 9 - the growth of mandible drops tongue, allowing palatine shelves to swing up and fuse with
________________ in the midline
and
______________ anteriorly
```
each other in the midline
| primary palate anteriorly
151
Pierre Robin Syndrome
| Defects in which embryonic germ layer and structures
First pharyngeal arch - neural crest
Mandibular prominence
Hypoplastic mandible
152
Treacher Collins Syndrome
| Defects in which embryonic germ layer and structures
First pharyngeal arch - neural crest
Mandibular and maxillary prominences
Hypoplastic zygoma, malformed pinna and ossicles...
153
Failure of fusion
| Lateral nasal prominence with maxillary prominence -->
Oblique cleft
154
Failure of fusion
| Palatine shelves
cleft palate
155
Failure of fusion
| Intermaxillary segment and maxillary prominence
cleft lip
