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BDS stage 2 > CTB theme 3 > Flashcards

CTB theme 3 Flashcards

1
Q

What are the steps in the estblishment of a body plan ?

A 
fertilisation
cleavage 
gastrualtion 
organogenesis 
larval stage
maturity
gametogenesis
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2
Q

What happens in gastrualation ?

A

development of the 3 germ layers

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3
Q

What are the 2 germ layers ?

A

ectoderm, endoderm and mesoderm

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4
Q

What happens in organogenesis ?

A

tissue morphogenesis and cell differentiation
formation of body structures and organs
germ layers make derivatives

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5
Q

What are the derivatives of the ectoderm ?

A

external cells- epidermis and dental epithelium
CNS
craniofacial tissues-cartialge, bone and teeth

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6
Q

What are the derivatives of the mesoderm ?

A

blood
connective tissue
notochord
bone

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7
Q

What are the derivatives of the endoderm ?

A

internal cells
stomach cells
thyroid cells
lung alveolar cells

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8
Q

What does susceptibiltiy to teratogens mean ?

A

human embryo can have developmental birth defects

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9
Q

When is the embryo susceptible to teratogens ?

A

first trimester- 3/4 weeks to 12 weeks

craniofacial abnormalities important in 4-12 weeks

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10
Q

What are some early head formation defects ?

A

holoprosencephaly

anencephaly

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11
Q

What is holoprosencephaly ?

A

facial midline defect due to deficiency in forebrain tissue

not symmetrical face

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12
Q

What causes holoprosencephaly ?

A

mutation in Shh pathways genes

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13
Q

What is anencephaly ?

A

abnormal brain development due to failure of neural tube to close

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14
Q

What causes anencephaly ?

A

teratogens
severe malnutrition
folic acid deficiency

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15
Q

What do high retinoic acid levels interfere with ?

A

Hox gene expression

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16
Q

What is an important early embryo development stage ?

A

folding of the early embryo

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17
Q

What are the 3 types of embryo folds ?

A

head
lateral
tail

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18
Q

What happens at 16 days in the embryo ?

A

3 germ layers present
ectoderm proliferates to form the neural palte
head fold occurs

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19
Q

What happens at 18 days in the embryo ?

A

ectoderm proliferates and meets endoderm forming the oropharyngeal membrane

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20
Q

What are the functions of the oropharyngeal membrane ?

A

separates the future mouth (stromedeum) from the pharynx
acts as a transient signalling centre to pattern the oral cavity
eventually broken down

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21
Q

What is the future mouth called ?

A

stromedeum

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22
Q

What happens in 22 days in the embryo ?

A

formation of the stromedeum

heart now located inwards

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23
Q

What happens in 30 days in the embryo ?

A

rudiments of most organs established
oropharyngeal membrane breaks down
pharyngeal arches broken down- 1, 2 and 3

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24
Q

What are the pharyngeal arches ?

A

1- mandibular arch
2- maxillary arch
3- third arch

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25
Q

What is present at 4 weeks of development ?

A

somites
heart
pharyngeal arches

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26
Q

What is the structure of the pharyngeal arches ?

A

each arch is covered in ectoderm and lined with endoderm

internal mesoderm core infiltrated with CNCs

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27
Q

What does each pharyngeal arch form ?

A

artery
cartilage
nerve

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28
Q

Why are there CNCs in the mesoderm of the pharyngeal arch ?

A

CNCs replace the mesoderm as they migrate into the arches

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29
Q

What is the artery and nerve formed in the first pharyngeal arch ?

A

maxillary artery

trigeminal

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30
Q

What is the artery and nerve formed in the second pharyngeal arch ?

A

hyoid artery

facial

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31
Q

What is the artery formed in the third pharyngeal arch ?

A

internal carotid artery

glossopharyngeal

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32
Q

What is the artery and nerve formed by the 4th pharyngeal arch ?

A

right subclavian

vagus

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33
Q

What are muscles of the 1st pharyngeal arch ?

A 
muscles of mastication 
anterior belly of digastric 
tensor tympani 
mylohyoid 
tensor veli palatini
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34
Q

What are the muscles of the 2nd pharyngeal arch ?

A

muscles of facial expression
stapedius
stylohyoid
posterior digastric

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35
Q

What are the muscles of the 3rd pharyngeal arch ?

A

stylopharyngeus

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36
Q

What are the muscles of the 4th pharyngeal arch ?

A

muscles of the larynx and pharynx

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37
Q

What are the skeletal derivatives of the 1st arch ?

A

malleus
incus
meckels
sternothyroid ligament

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38
Q

What are the skeletal derivatives of the 2nd arch ?

A

stapes
styloid process
stylohyoid ligament
lesser cornu of hyoid

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39
Q

What are the skeletal derivatives of the 3rd arch ?

A

greater cornu of hyoid

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40
Q

What are the skeletal derivatives of the 4th arch ?

A

laryngeal cartilages

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41
Q

What is the process of cranial neural crest cell formation ?

A
  1. CNCs induced molecularly at the border between neuroectoderm and epidermis
  2. neural plate invaginates and forms the neural folds- open tube
  3. neural folds fuse to form the neural tube - CNCs migrate along specific pathways
  4. migration to predetemined destinations - become specialised cell types
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42
Q

Where are CNCa specified ?

A

at the border between neuroectoderm and epidermis

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43
Q

What does the border of neuroectoderm and epidemris specify and create ?

A

specifies CNCs

creates BMP4 and WNT6 signalling proteins

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44
Q

What do BMP4 and WNT6 do ?

A

indice TFs necesary for CNC migration and specification

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45
Q

What are the gradients of BMP4 and WNT6 ?

A

overlapping gradients

cells get intermediate signals and migrate to where theyre determined

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46
Q

What do CNC do in migration ?

A

migrate along specific pathways from the early brain to pharyngeal arches

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47
Q

What determines CNC identity ?

A

overlapping expression of homoeobox TFs - determine CNC identity

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48
Q

What happens in the development of the face at 4-5 weeks ?

A

formation and growth of an unpaired frontonasal prominence
formation of nasal placodes (epithelium thickenings)
formation of paired nasomedial/nasolateral processes which form the nasal pit
formation and growth and merger of the mandibular processes
Formation and growth of paired maxillary processes

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49
Q

What does the mandibular arch divide into ?

A

mandibular and maxillary processes

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50
Q

What happens in the development of the face (5-6 weeks) ?

A

Recession of the nasolateral prominence due to excessive growth of the nasolateral process
Growth of the nasolateral process which fuses with the maxillary process

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51
Q

What does the fusion of maxillary process and nasolateal process form ?

A

nasolacrimal duct
cheek
alar base of nose

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52
Q

What happens in the development of the face at 7-8 weeks ?

A

merger of the nasomedial process

further growth of maxillary processes and fusion with nasomedial process

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53
Q

What does fusion of the maxillary process and nasomedial process lead to ?

A

central part of nose, upper lip and primary palate
upper lip laterally- maxillary process
upper lip medially- nasomedial process - philtrum

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54
Q

What does the maxillary process form ?

A

maxilla

lateral part of the upper lip

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55
Q

What does the mandibular process form ?

A

mandible

upper lip

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56
Q

What does the medial nasal process form ?

A

medial part of the nose
medial part of the upper lip
primary palate

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57
Q

What does the lateral nasal process form ?

A

lateral part of the nose

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58
Q

What is median cleft lip ?

A

single cleft in the midline

failure of medial nasal processes to fuse

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59
Q

What is bilateral cleft lip ?

A

cleft from nose to upper lip

failure of maxillary and medial nasal processes to fuse

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60
Q

What is an oblique facial cleft ?

A

persistence of the nasolacrimal groove

failure of maxilllary and lateral nasal process to fuse

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61
Q

What is lateral facial cleft ?

A

macrostomia
failure of merger between mandibular and maxillary process
cleft from the lip on the cheek

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62
Q

What is the median mandibular cleft ?

A

from the lower lip to chin
failure of merger of mandibular processes
chin dimple

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63
Q

Why is median cleft lip associated with cleft palate ?

A

both the upper lip and the palate are due to fusion of mesiolateral processes

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64
Q

What is frontonasal dysplasia ?

A

various degrees of excessive tissue in frontonasal process
broad nasal bridge
hypertolerism
cleft nose and median cleft

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65
Q

What are the range of clinical presentations of hypertolerism ?

A

single genetic pathways

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66
Q

What is treacher collins syndrome ?

A

hypopalsia of mandible and facial bones
macrostomia
cleft palate
eyelid coloboma

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67
Q

What causes treacher collins syndrome ?

A 
mutation in Tcof1
decreased ribosome biogenesis 
increased p53
cell cycle arrest and apoptosis 
lost of neural crest cells
hypoplasia of facial bones
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68
Q

How can we prevent treacher collins syndrome ?

A

inject inhibitor of p53- prevent apoptosis

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69
Q

How does the primary palate develop ?

A

Nasal pits relocated inwards
thin oronasal membrnae separate oral and nasal cavities
primary palate forms from the merger of mesionasal processes that grow inwards into the oral cavtity

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70
Q

How does the primary palate form ?

A

ingrowth and merger of nasomedial processes

form median palatal process

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71
Q

What does persistence of the oronasal membrane cause ?

A

choanal artesia
tissue blocks nasal passage
complete or partial
bilateral or unilateral

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72
Q

What does the secondary palate form from ?

A

lateral outgrowths of maxillary processes

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73
Q

What does the secondary palate close ?

A

the space between the oral and nasal cavity

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74
Q

How does the secondary palate form ?

A

lateral palatine processes appear as maxilalry outgrowths - grow downwards
palatal shelves elevate
downgrowth of the nasal septum
fusion of the palatal shelves in the anterior part and the primary palate
Fusion of the palatal shelves in the posterior part and formation of the palatal raphe

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75
Q

What is present at the border of the primary and secondary palate ?

A

incisive foramen - blood vessels and nerves to the hard palate

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76
Q

How does the uvula form ?

A

from the medial soft palate

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77
Q

What are the functions of the uvula ?

A

swallowing
speech
reflex
breathing

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78
Q

What is the proposed mechanism of palatal shelf elevation ?

A

GAGs at the hinges

GAGs hydrate- causing elevation

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79
Q

How do the palatal shelves meet and fuse ?

A

meet through the growth of mesenchymal cells

Fusion of the shelves from the Medial epithelial seam

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80
Q

What happens to the medial epithelial seam ?

A

it is removed apoptolytically

results in continuous secondary palate

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81
Q

What happens in van der woude syddrome ?

A

fusion of the palatal epithelia with other oral epithelia

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82
Q

Which mutation causes van der Woude syndrome ?

A

IRF6

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83
Q

What does incomplete removal of epithelial remnanats of MES lead to ?

A

palatal cysts

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84
Q

What are palatal cysts ?

A

benign

interfere with denture fitting

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85
Q

What is an early growth or morphogenetic effect in the palate ?

A

failure of palatal shelf formation due to reduced mesenchymal cell proliferation

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86
Q

What causes premature epithelial fusion ?

A

epithelium of the palatal shelves fuses with oral epithelia

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87
Q

What is failure of palatal shelf elevation ?

A

obstruction or abnormal cell differentiation in hinge region of palatal shelves

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88
Q

What is a late growth defect ?

A

failure of shelves to meet after elevation
reduced mesenchymal cell proliferation
head too wide

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89
Q

What is a unilateral cleft palate ?

A

from the nose, lip and primary palate

can be bilateral

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90
Q

What are the types of secondary palate clefts ?

A

unilateral– one palatal shelf fused with the nasal septum

bilateral- both palatal shelves fused with the nasal septum

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91
Q

What are the bones of the hard palate ?

A

premaxillary part of maxilla (not part of maxilla)
palatine process of maxilla
horizontal plate of palatine bone

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92
Q

What is the premaxilla ?

A

primary palate

holds the incisors

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93
Q

What does the palatine process of maxilla do ?

A

fuse with the premaxilla

and then the horizontal process of palatine bone

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94
Q

Which teeth are likely to be missing in the cleft lip area ?

A

2s and 5s

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95
Q

What is torus platinus ?

A

late defect

benign outgrowth in midline of hard palate

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96
Q

What are the types of CL/P or CP ?

A

syndromic or isolated

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97
Q

What are the causes of syndromic CL/P or CP ?

A

single gene mutation in coding regions
affect gene function more strongly
pleitropic effects in multiple organs

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98
Q

What are the causes of isolated CL/P or CP ?

A

mutations in gene regulatory DNA regions- effect tissue specific expression
genetic and environmental interactions

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99
Q

What are the environmental risk factors for CL/P and CP ?

A

deficiencies in maternal diet
excessive or insufficient mineral intake
alcohol, tobacco
teratogens- nitrates

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100
Q

What is the gene mutation in holopresencephaly ?

A

SHH

GLI2

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101
Q

What is the gene mutation in van der woude syndrome ?

A

IRF6

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102
Q

What is the gene mutation in crouzon ?

A

FGFR2

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103
Q

What is the gene mutation in Apert ?

A

FGFR2

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104
Q

What is the gene mutation in pierre robin ?

A

SOX9

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105
Q

What is the mutation in di george ?

A

TBX1

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106
Q

What is the gene mutation in treacher collins syndrome ?

A

Tcof1

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107
Q

What is the genetic module common to both palate and tooth development ?

A

Pax9 initiated in mesenchyme
signalling cascade between MSX1 and BMP
Signals back to epithelium to form enamel knot
expression of Shh by enamel knot

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108
Q

How is the anterior tongue formed ?

A

appearance of 3 swellings on 1st pharyngeal arch- tuberculum impar and 2 lateral lingual swellings
lateral lingual swellings enlarge rapidly and fuse with each other and tuberculum impar

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109
Q

How is the posterior tongue formed ?

A

hypobachial eminence on PA 3 and 4

overgrows the copula - PA 2

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110
Q

What is at the border between the anterior and posterior tongue ?

A

teminal sulcus

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111
Q

Where is the anterior tongue derived from ?

A

ectoderm epithelium

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112
Q

Where is the posterior tongue derived from ?

A

endoderm epithelium

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113
Q

What is the foramen caecum ?

A

between copula and tuberculum impar

marks original location of the thyroid primordium

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114
Q

What is the thyroid primordium ?

A

migrates down towards the 3rd tracheal cartilage

stays connected to the thyroglossal duct during migration

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115
Q

How is the epiglottis formed ?

A

posterior part of 4th pharyngeal arch

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116
Q

Where do the tongue muscles derive from ?

A

occipital somites that have migrated forward

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117
Q

What is the innervation of the anterior 2/3 of the tongue ?

A

lingual nerve and chorda tympani

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118
Q

What is the innervation of the posterior 1/3 of the tongue ?

A

glossopharyngeal

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119
Q

What is the innervation of the epgiglottis ?

A

vagus

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120
Q

What is ankyglossia ?

A

tongue tie
thick lingual frenulum
impaired tongue movement
van der Woude syndrome

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121
Q

What is macroglossia ?

A

tongue hyperplasia
downs syndrome
due to acromegaly- too much GH

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122
Q

What are developmnetal defects of thyroid migration ?

A

ectopic thyroid tissue
lingual thyroid
thyroglossal duct sinus

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123
Q

What are the rods of hyaline cartilage that form either side of the jaw in mandible development ?

A

meckels cartilage

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124
Q

How far does meckels cartilage extend ?

A

from the optic capsule to the midline of the merged mandiible

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125
Q

What does meckels cartilage do in mandible development ?

A

forms a framework that the mandible can develop arounf

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126
Q

Where is osteogenesis initiated in the mandible ?

A

at the branching of the mental and incisive nerve

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127
Q

How does osteogenesis happen in the mandible ?

A

via lateral mesenchymal cell proliferation

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128
Q

How does the mandible grow ?

A

it takes the shape of a trough under the incisive nerve
meckels process gets smaller and the alveoalr process grows under the tooth germ
meckels cartilge is resorbed and the nerve is in a bony canal and the alveolar process surrounds the tooth germ

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129
Q

When does the symphysis that joins the 2 mandible bones develop ?

A

10 weeks

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130
Q

How does the lingula form ?

A

when mandible diverts from meckels cartilage

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131
Q

Where does the incisive nerve enter the mandible ?

A

at mandibular foramen

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132
Q

What is attached to the lingula ?

A

sphenomandibular ligament

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133
Q

What are the attachments of the sphenomandibualr ligament ?

A

spine of sphenoid to lingula of the mandible

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134
Q

What forms the sphenomandibular ligament ?

A

perichondrium

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135
Q

What is the fate of meckels cartilage ?

A

meckels cartilage degrades in the middle- dorsal and ventral remnants remain
space filled with bone
(not endochondral)

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136
Q

What do the dorsal remnants of meckels cartilage form ?

A

ossfiy to form incus
malleus
spine of spehnoid

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137
Q

What do the ventral remnants of meckels cartilage from ?

A

lingula

mental ossicles

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138
Q

What type of cartilage is meckels cartilage ?

A

priamary cartilage

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139
Q

What are secondary cartilages ?

A

associated with membranous bone
form later in development
larger cells and less ECM

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140
Q

What are the 3 secondary cartilages associated with the mandible ?

A

condylar cartilage
coronoid cartilage
symphyseal cartilage

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141
Q

What is the condylar cartilage ?

A

carrot shaped
enters mandible
continue to grow until 16-20 years
grows via the endochondral growth plate

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142
Q

What is the coronoid cartilage ?

A

transient and ossified fully before birth

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143
Q

What is the symohyseal cartilage ?

A

forms mental ossicles

ossified at 1/2 years

144
Q

What is the mandibular symphysis ?

A

not true symohyseal joint more like a suture

145
Q

What is a suture ?

A

bones connected by fibrous tissue that enables growth and stability

146
Q

When does the mental protuberance form ?

A

after puberty

147
Q

What is a fibrous joint ?

A

two bones connected by fibres
growth still occurs
little movement- provide stability

148
Q

Give an example of a fibrous joint ?

A

PDL
mediates tooth attachmnet between cementum and bone
acts as shock absorber and responds to masticatory and intrusive forces

149
Q

What is a cartilaginous joint ?

A

bones connected by cartilage

two types- primary and secondary

150
Q

What is a primary cartilaginous joint ?

A

bones joined by cartilage only

costochondral joint

151
Q

What is a secondary cartilaginous joint ?

A

fibrous portion in the middle

pubic symphysis- stretch in birth

152
Q

What is a synovial joint ?

A

2 bones are articular surfaces
covered with hyaline cartilage in a joint cavity filled with synovial fluid
eg. TMJ

153
Q

How does the articular disc enter the lateral pterygoid ?

A

via a tendon

154
Q

What is the articular disc divided into ?

A

anterior and posterior bands

intermediate zone - thin

155
Q

Which types of movements can the TMJ carry out ?

A

Rotational- horizontal

translational

156
Q

What is the position of the disc in a closed mouth ?

A

posterior band is situated above the condyle

157
Q

What is the position of the disc in an open mouth ?

A

condyle translates forward

intermediate zone is now the articular eminence

158
Q

What is the position of the disc in a fully open mouth ?

A

Anterior band is situated above the condyle

159
Q

What forms the TMJ ?

A

mesenchymal cells

160
Q

How is the TMJ formed ?

A

12 weeks
2 clefts appear in mesenchyme- form the upper and lower cavities
intervening mesenchyme between the clefts becomes the disc
joint capsule forms from the mesenchymal cell condensation around the joint

161
Q

How does the articular eminence form ?

A

after tooth eruption

needed functionally in the mouth when there is teeth present

162
Q

What is the condyle covered with ?

A

fibrous tissue - contains progenitor cells that contain chondorcytes for endochondral ossification

163
Q

What is the mandibular fossa of the temporal bone covered in ?

A

outer fibrous layer- more fibrous for articulation

inner cellular layer

164
Q

What are the layers of cells on the condyle ?

A

under the fibrous layer there is the proliferative layer
hypertrophic zone- Large cells due to excess ECM cartilage production
calcified cartilage

165
Q

What does the proliferative layer of the condyle allow ?

A

the cells in the proliferative layer can divide into chondrocytes that produce cartilage allowing condylar growth until 16-20 years.

166
Q

What is the difference between a developing and adult condyle ?

A

adult condyle has a reduced proliferative layer

adult condyle has calcified cartilage and fibrocartilage zone

167
Q

What do the cells of the proliferative layer of the condyle do ?

A

persist throughout life and can respond to fucntional changes like masticatory stress

168
Q

What is the basis for orthodontic treatment ?

A

articualr surfaces can be remodelled via the proliferative layer - excess in young

169
Q

What are the features of the articular eminence ?

A

no endochonrally ossified cartilage- fibrocartilage isntead
proliferative layer responds to fucntional changes that induce remodelling
thick layer of fibres cover surface for articulation

170
Q

What is the synovial membrane ?

A

lines the capsule
bilayered folds that protrude into the cavity and produce synovial fluid
more folds with pathology and age

171
Q

What is the purpose of the TML ?

A

prevents posterior, inferior, lateral and medial displacement

172
Q

How does TMJ dislocation happen ?

A

in the forward direction

condyle slips over and past the articular eminence

173
Q

What are the attachment of the temporalis ?

A

from the temporal fossa to the coronoid process and the ramus of the mandible

174
Q

What can cause bruxism lead to ?

A

jaw pain

175
Q

What can epileptic seizures cause ?

A

rupture the tendon between temporalis and coronoid

176
Q

What are the attachments of the masseter ?

A

from the zygomatic arch to the angle of the mandible and ramus

177
Q

What are the attachments of medial pterygoid ?

A

superficial head from maxilalry tuberosity to the ramus

deep head from the spine of sphenoid to ramus

178
Q

What are the attachments of lateral pterygoid ?

A

superior head from the GWS to the neck of the condyle and joint capsule
inferior head from lateral pterygoid plate to condylar neck and TMJ capsule

179
Q

What is the TMJ innervated by ?

A

CN V

180
Q

Which nerve types innervate the TMJ ?

A

free nerve endings
ruffinis corpuscles
golgi tendon organs
pacini

181
Q

What is the function of the free nerve endings in the TMJ ?

A

widely distributed to sense pain and allow joint protection

182
Q

What is the purpose of ruffinis corpuscles ?

A

encapsualated
joint cpasule
proprioception- joint posture

183
Q

What is the purpose of golgi tendon organs ?

A

encapsulated
in joint ligaments
sense extreme joint movements for ligament protection

184
Q

What are pacicni corpuscles ?

A

least abundant
encapsualted
associated with joint capsule
sense pressure and vibration

185
Q

What happens to the mandible in Treacher collins syndrome ?

A

small mandible - micrognathia

lack of zygoma

186
Q

What happens to the mandible in pierre robin sequence ?

A

small mandible
cleft palate
base of tongue too far back

187
Q

What happens to the mandible in acromegaly ?

A

large mandible

pituitary tumour- high GH

188
Q

What is hemifacial microsomia ?

A

lower half side of face is underdeveloped

facial assymetry

189
Q

What happens in TMJ disorder ?

A

pain
dysfucntion
restricted jaw movements
clicking

190
Q

What are causes of TMJ disorder ?

A

neurological
musculoskeletal
rhematological

191
Q

How can facial assymetry be caused ?

A

ankylosis due to trauma and infection

192
Q

What is anterior displacement ?

A

posterior band of disc in front of condyle

bilaminar zone abnormally stretched

193
Q

What is AP with reduction ?

A

return to original position leading to popping sound

194
Q

What is AP without reduction ?

A

not return to position

grinding sound of AE and condyle

195
Q

What is eagle stylohyoid ligament ?

A 
elongated styloid process 
calcified stylohyoid ligament 
orofacil pain 
diagnose with CT scan 
remove styloidectomy
196
Q

What is endochondral ossification ?

A

bones are made from a cartilage model

chondorcytes produce cartilage and this is replaced by osteoid from osteoblasts

197
Q

Where does endochondral ossification take place ?

A

long bones via the epiphyseal growth plate
mandibular condyle via secondary cartilages
base of the skull- synchondrosis

198
Q

What is intramembranous ossification ?

A

bones are made from osteoblasts that have differentiated from mesenchymal stem cells

199
Q

Where does intramembranous ossification take place ?

A

facial bones
flat skull bones
mandible
maxilla

200
Q

What is sutural ossification ?

A

fibrous tissue between bones that allows stability during skull growth

201
Q

How do endochondral bones develop ?

A

Perichondrium made from chondrocytes derived from mesenchymal stem cells
Makes the cartilage model
perichondrium in the diaphysis makes osteoblasts- periosteum
produce a collar of bone - cortical bone
cartilage begins to calcify
blood vessels invade cartilage and introduce osteoblasts and osteoclasts- primary ossification centre
bone trabeculae made link to collar bone
Secondary ossification centres made in diaphysis via blood vessel invasion

202
Q

How is growth in bone length mediated ?

A

epiphyseal growth plate

203
Q

How is growth in bone thickness mediated ?

A

via the periosteum

204
Q

What is present between the epiphysis and diaphysis ?

A

epiphyseal growth plate

a cartilaginous growth plate

205
Q

What are the cellular layers of the epiphyseal growth plate ?

A 
resting chondorcytes 
proliferating chondrocytes 
prehypertrophic chondrocytes 
hypertrophic chondorcytes 
calcification zone
206
Q

What are resting chondorcytes ?

A

reservoir of chondrocytes to replenish dead chondrocytes

207
Q

What are proliferating chondrocytes ?

A

chondrocytes are aligned in columns
secrete cartilage matrix
collagen type II

208
Q

What are prehypertrophic chondrocytes ?

A

Chondrocytes begin to swell with the increased production of cartilage
collagen type X

209
Q

What are hypertrophic chondrocytes ?

A

fully matured chondrocytes that eventually die via apoptosis

210
Q

What happens in calcification zone ?

A

cartilage matrix is replaced by osteoid

211
Q

What is a sychondroses ?

A

cartialaginous joints between bones of the cranial base

212
Q

What are synchondroses like ?

A

mirror image of the epiphyseal growth plate

213
Q

What do synchondroses allow ?

A

growth of the cranial base during puberty in all directions

like between the sphenoid and occipital bones

214
Q

What is the condylar cartilage ?

A

associated with the intramembranous bone - mediates growth of the condyle - intramembranous bone

215
Q

What is epiphyseal cartilage ?

A

mediates growth of the endochondral bonses

216
Q

How is cartilage formed in epiphyseal growth plate ?

A

cartilage formed by chondorcyte proliferation, maturation and hypertrophy

217
Q

How is cartilage produced in the condyle ?

A

mesenchymal cells respond to fucntional loading and differentiate into chonrocytes

218
Q

How are chondorcytes aligned in epiphyseal cartilage ?

A

in columns - allows growth lengthwise in long bones

219
Q

How are chondrocytes aligned in condylar cartilage ?

A

randomly- allows growth in a multi dimensional capacity.

220
Q

What is a suture ?

A

fibrous joint between 2 skull bones that enables a response to mechanical stress and allows bone growth in response to brain growth

221
Q

What are the 2 layers of a suture ?

A

cambrian layer- cellular layer that contians osteoblasts that allow bone growth
capsular layer- more fibrous and contains fibroblasts that provide stabilty

222
Q

What are the bones of the cranial base ?

A 
ethmoid
sphenoid 
petrous part of temporal 
basiocciput 
exoccipital
223
Q

What are the bones of the face ?

A

mandible
maxilla
zygomatic
nasal bones

224
Q

What are the bones of the cranial vault ?

A

frontal
parietal
temporal
occipital

225
Q

What is the neurocranium ?

A

cranial vault and cranial base

surrounds the brain

226
Q

What is the viscerocranium ?

A

facial skeleton
surrounds the oral cavity
pharynx and upper respiratory tract

227
Q

How is the skull base mainly formed ?

A

endochondral

228
Q

How are flat bones mainly formed ?

A

intramembranous

229
Q

What is the endochondral neurocranium ?

A 
occipital 
body of sphenoid 
ethmoid 
petrous
mastoid process
230
Q

What is the intramembranous neurocranium ?

A

interparietal part of occipital bone
parietal part of temporal
frontal bone
squamous part of temporal bone

231
Q

What is the membranous viscerocranium ?

A 
maxillary process
squamous part of temporal 
zygomatic 
maxilla 
premaxilla 
mandible 
tympanic ring
232
Q

Which germ layer forms the anterior bones ?

A

neural crest

233
Q

Which germ layer forms the posterior bones ?

A

mesoderm

234
Q

How is the cranial vault formed ?

A

5 weeks IU

intramembranous ossification

235
Q

What are the bones of the cranial vault ?

A

frontal
parietal
squamous temporal
squamous occipital

236
Q

How does intramembranous ossification progress in cranial vault ?

A

ossification progresses until the bones meet at sutures or frontanelles
7 months IU

237
Q

What are sutures ?

A

coordinate skull growth in response to brain growth

close in adulthood

238
Q

What are fontanelles ?

A

enlarged sutures where 3 or more bones meet
needed for flexibility to pass down the birth canal
variable postnatal closure

239
Q

What does premature fusion of the sutures lead to ?

A

craniosynostosis

240
Q

What is the mechanism of craniosynostosis ?

A

FGFR2 mutation

premature closure of sagittal or coronal suture

241
Q

What does premature closing of the sagittal suture lead to ?

A

scaphcephaly
long narrow skull
cant grow sideways

242
Q

What does premature closure of the coronal suture lead to ?

A

bracycephaly

short skull

243
Q

What is plagiocephaly ?

A

closure of the coronal suture on one side

244
Q

How does the cranial base develop ?

A

endochondral ossification

245
Q

Describe the development of the cranial base ?

A

cartilages extend fro the cranial end of the notochord to the nasal capsule
cartilages grow towards each other and fuse at 8 weeks IU to form endochondral bones

246
Q

What do the occipital scleretomes and parachordial cartialges form ?

A

basilar part of occipital

condylar part of occipital

247
Q

What do the hypophyseal and trabecular cartilages form ?

A

body of sphenoid

248
Q

What do the trabecular and nasal cartialges form ?

A

perpendicular plate of ethmoid

crista galli of ethmoid

249
Q

What do the ala orbitalis and ala temporalis form ?

A

lesser and greater wings of sphenoid

250
Q

What does the otic capsule and lateral part of the parachordial cartilage form ?

A

petrous part and mastoid process of temporal bone

251
Q

What do the paired nasal cartilages and prechordal cartilages form ?

A

nasal cavity

252
Q

What is a synchondroses ?

A

cartilaginous joint that acts as a growth centre

253
Q

What is the purpose of synchondroses ?

A

development and growth influences structure and dimensions of craniofacial skeleton

254
Q

What are the 3 types of synchondroses in the cranial vault ?

A

inter sphenoidal synchondroses
spehno-ethmoidal synchondoroses
sphenooccipital synchondroses

255
Q

When does the intersphenoidal synchondrosis ossify ?

A

7 months IU

256
Q

When does the sphenoethmnoidal synchondrosis form ?

A

7 years

257
Q

When does sphenoccipital synchondrosis form ?

A

13-17 years at age

258
Q

Where does ossification start in the mandible and maxilla at 7 weeks IU ?

A

mandible- branching of the mental and incisive nerve
maxilla- primary canine
ossification spreads rapidly
meckels cartilage starts getting resorbed

259
Q

What are simple bones ?

A

formed from ossification of one element

eg. endochondral bone ossifies at malleus

260
Q

What is a compound bone ?

A

formed from the fusion of 2 or more ossifying elements

can be both chondral or both intramembranous or mix

261
Q

What is an example of a compound bone ?

A

sphenoid bone
body- 2 parts ossify endochondrally
Lesser wing- ossified endochondrally before birth
GWS and Lpt- starts endochondrally and spreads intramembranously
Mpt- intramembranously

262
Q

What are the parts of the occipital bone ?

A

supraoccipital
basiooccipital
exoccipital
interparietal

263
Q

What is different about a foetal head ?

A

mandible not fused - visible symphysis
large forehead, small face and large eyes
small face as no need for large masticatory apparatu s

264
Q

Which bones form the hard palate ?

A

premaxilla
palatal process of maxilla
horizontal plate of palatine bone

265
Q

What is the importance of understanding craniofacial growth ?

A

orthodontic treatment is carried out to modify craniofacial growth
facial growth directly influences skeletal relationship of jaws

266
Q

How does the mandible grow ?

A

elongation of condyle and ramus in posterior superior direction
body of mandible lengthens

267
Q

Which skull components grow as a cartilaginous joint ?

A

synchondroses and condyle

268
Q

Which skull components grow at sutures ?

A

cranial vault

nasomaxilalry complex

269
Q

Which bones grow via bone remodelling ?

A

all bones

270
Q

What is relocation ?

A

bone deposition and formation on oppsing surface of a bone cause bone to drift into space towards the deposition side

271
Q

What is displacement ?

A

external forces generated by growing soft tissues

separate bones from each other allowing compensatory bone growth into space

272
Q

What does nanci say about remodelling ?

A

size increase if deposition is greater

273
Q

What is drift ?

A

equal bone deposition and resorption on oppsing surfaces allows the bone to move into space

274
Q

What is displacement ?

A

growth in one location causes the bone to be pushed away

275
Q

What is secondary displacement ?

A

relocation of bones that are not growing themselves

276
Q

What is rotation ?

A

result of reversed deposition and rotation fields around the central axis

277
Q

How does the cranial base grow ?

A

via synchondroses and remodelling

278
Q

What is a synchondroses ?

A

cartilaginous joint that acts as a growth centre

279
Q

What are the 3 synchondroses ?

A

sphenoccipital synchondroses
sphenoethmoidal synchondroses
intersehnoidal synchondroses

280
Q

What is the sphenoccipital synchondroses ?

A

ossifies at 13-17 years

allows cranial base growth

281
Q

What is the sphenoethmoidal synchondroses ?

A

ossfies at 7 years

anterior cranial abse growht

282
Q

When does the intersphenoidal synchondroses ossify ?

A

at 7 months

283
Q

What does growth of the spehnoccipital synchondroses influence ?

A

affects the angle of cranial base

influences facial form

284
Q

What is a class I relationship ?

A

orthognathic

285
Q

What is a class II relationship ?

A

retrognathic

286
Q

What is a class III relationship ?

A

prognathic

287
Q

What is enlows hypothesis ?

A

craniofacial development is integrated

288
Q

What type of head is associated with class II ?

A

dociocephalic

289
Q

What type of face is associated with class II ?

A

leptoprosopic

290
Q

What leads to a class II ?

A

cranial base is obtuse

backwards rotation of the mandible

291
Q

What is the profile of a class II face ?

A 
long narrow head
convex profile 
glabella and supraorbital ridges 
sloped forehead 
long and thin nose
292
Q

What type of head is associated with class III ?

A

bracycephalic

293
Q

How is a class III produced ?

A

angle of the cranial base is acute

forwards rotation of amndible

294
Q

What type of face is associated with class III ?

A

euryprosopic

295
Q

What is the facial profile of class III ?

A

round and wide space
forehead upright
glabella and supraorbital ridges inconspicuous
short and wide nose

296
Q

What causes mandibular rotation ?

A

growth of cervical region of vertebral region displaces the head from the shoulder girdle
growth stretches muscle groups
descent of mandibular symphysis and hyoid bone leads to increased anterior facial growth
posterior facial height increases due to condyle growth

297
Q

What leads to mandibular rotation ?

A

extreme anterior or posterior facial growth

298
Q

What leads to forward rotation ?

A

excess posterior facial growth
forward rotation of mandible
deep bite and prognathic mandible

299
Q

What leads to backward rotation ?

A

excess anterior facial growth
backwards rotation
open bite
retrognathic mandible

300
Q

What can restore normal occlusion after mandibular rotation ?

A

dentoalveoalr compensation

mandibular rotation

301
Q

What is mandibular compensation ?

A

obtuse angle- backwards rotation

retrognathism can be repaired by growth of ramus- pushes teeth forward- correct predisposition for malocclusion

302
Q

What is dentoalveolar compensation ?

A

backwards rotation can result in anterior open bite

mandibular and maxillary incisors grow to compensate

303
Q

How does the cranial vault grow ?

A

displacement- skull growth by periosteal bone deposition on both sides of suture to maintain patency

bone remodelling– depostion and resorption occurs on internal and external surfaces to reduce curvature

304
Q

How does craniosynostosis occur ?

A

premature fusion of sutures

brain expansions results in excess bone growth in regions of skull that are parallel to prematurely closed suture

305
Q

What type of head is in sagittal craniosynostosis ?

A

long and narrow

306
Q

What type of head is in coronal craniosynostosis ?

A

bilateral

increases in width

307
Q

How do the nasomaxillary complexes grow ?

A

sutural growth

308
Q

How does the maxilla increase in height ?

A

due to downwards growth
bone deposition in zygoamtic and frontal sutures
remodelling at alveolar processes
remodelling at hard palate- deposition on internal hard palate and resorption on external palate

309
Q

How does the maxilla grow in width ?

A

lateral growth

growth at midpalatal suture

310
Q

What causes the increase in maxillary length ?

A

forward growth in maxilla

311
Q

How does maxillary length increase ?

A

growth at posterior surface of maxillary tuberosities
backwards growth causes forward displacement
remodelling in area above incisors

312
Q

What are the characteristics of a newborn mandible ?

A

smaller and narrower mandible
obtuse mandible angle
no erupted teeth
symphysis still visible

313
Q

How does the mandible grow ?

A

forward and downward displacement of mandible
growth of condylar cartilage
bone remodelling of ramus - deposition of posterior ramus margin, resorption on anterior ramus margin
backward and upward growth of mandible

314
Q

How does the mandible grow laterally ?

A

lateral growth occurs in complex bone remodelling along lateral and lingual surfaces of condyle, coronoid, ramus and mandible

315
Q

What are the differences between neonatal and adult skull ?

A

neonatal face is smaller, large cranial vault and orbits
smaller bones
6 fontanells- close at 18 months
metopic suture still opne
symphyseal suture open - closes at 1/2 yeard
sphenoccipital synchomdroses

316
Q

What is a female facial profile ?

A 
facial growth stops after puberty 
flatter and more delicate face
overhang of supra orbital ridges 
prominent zygoamtic bone 
thinner and less prominent nose
317
Q

What is a male facial profile ?

A

facial growth continues into 20s
bulky face wider and longer airwayd
roman nose and greek nose

318
Q

What is the gonial angle ?

A

angle of the mandible

319
Q

What are the 5 parts of the occipital bone ?

A

supraoccipital
basioccipital
interparietal
exoccipital x 2

320
Q

What are the feature of cleidocranial dysplasia ?

A 
Malformed tooth roots
Hyperdontia
Hypertelorism 
Short cranial base
Bracycephalic bulldog
Class III 
no shoulder blades
321
Q

What causes craniosynostosis ?

A

FGFR2 mutation

322
Q

Why is there an increased intercranial pressure in craniosynostosis ?

A

brain grows and there is not enough space for brain to grow into
impairs mental development

323
Q

Why is their proptosis in craniosynostosis ?

A

underdeveloped orbits
shallower orbits
popping eyes

324
Q

What causes crouzons syndrome ?

A

FGFR2 mutation

325
Q

What are the features of crouzons syndrome ?

A 
bicoronal and sagittal synostosis 
Bracycpehalic 
short head and short cranial base 
increase in intracranial pressure 
Hypoplastic maxilla
326
Q

What causes aperts syndrome ?

A

FGFR2 mutation on chromosome 7

327
Q

What is aperts syndrome ?

A

crouzons with clawe digits - syndactyly

328
Q

What is the mutation in Treacher collins syndrome ?

A

TCOF1

mutation in treacle gene

329
Q

What are the features of treacher collins syndrome ?

A 
small mandile- class II
cleft palate
downwards sloping eyes
coloboma 
learning difficulties 
hearing diffculties
330
Q

Why are there hearing difficulties in treacher collins ?

A

first arch structures are affected- malleus and incus

331
Q

What is hemifacial microsomi ?

A

underdeveloped side of the mandible

332
Q

What are the features of hemifacial microsomia ?

A

small mandible on one side
small ears
narrow eyes
flat maxilla

333
Q

What are the causes of CL/P ?

A

classic eratogens
anti epileptics
diazepam
corticosteroids

334
Q

Which teeth are most likely missing in cleft lip/palate ?

A

2 and 5

335
Q

What are dental abnormalities in cleidocranial dysplasia ?

A

abnormal roots

delayed tooth eruption

336
Q

What can cleft lip palate surgery lead to ?

A

severe class III

337
Q

What is the nasion ?

A

Where the frontal and nasal bones meet

338
Q

What is the menton ?

A

lowest point of mandibular symphysis

339
Q

What is the gonion ?

A

the most posterior inferior part of the angle of the mandible

340
Q

What is the maxillary plane ?

A

from the ANS to the PNS

341
Q

What is the mandibular plane ?

A

from the metnon to the gonion

342
Q

What is the anterior cranial base ?

A

from the nasion to the sellla turcica

343
Q

Which angles of the cephalometrry can be used to estimate skeletal relationships ?

A

SNB - 78
SNA- 81
ANB - 3

344
Q

What is the ANB in class I ?

A

2-4

345
Q

What is the ANB in class II ?

A

bigger than 4

346
Q

What is the ANB in class III ?

A

less than 2

347
Q

What is the developmental relationship between mylohyoid and meckels cartilage ?

A

mylohyoid develops with meckels cartilage
mylohyoid joins mandible to hyoid bone
when meckels cartilage is resorbed it must be transferred to the mandible via the perichondrium

348
Q

What is the consequence of incomplete removal of MES ?

A

leads to palatal cysts

reinduced by signals

349
Q

What happens at 16-20 years to the condylar cartilage ?

A

converted to fibrocartilage

350
Q

What is the structure of a synchondroses ?

A

bilateral epiphyseal growth plate
allows growth in 2 directions
resting chondrocytes in the midline

351
Q

What does the intersphenoidal synchomndroses connect ?

A

connects the basisphenoid and the the presphenoid

352
Q

What does the sphenoccipital synchondroses connect ?

A

connects the basispehnoid with the basiocciput

353
Q

What does the sphenoethmoidal synchondroses connect ?

A

presphenoid and the ethmoid

354
Q

How does the maxilla grow in width ?

A

deposition at the mid-palatal suture

355
Q

Is the maxilla a compound or simple bone ?

A

it is a compound bone- fusion of premaxill and maxilla

both formed from intramembranous

BDS stage 2 (28 decks)

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