1. Craniofacial development Flashcards
1
Q
Proportion of babies with craniofacial defects
A
1/700
2
Q
Holoprosencephaly results in
(4)
A
- Nasal proboscis
- Failure of telencephalon to bifurcate
- Loss of nasal Septum
- Cyclopoeia
3
Q
What defect?
A
Holoprosencephaly
4
Q
Causes of Holoprosencephaly in live births
(5)
A
- Congenital ~25%, otherwise environmental
- Diabetic Mothers
- Alcohol
- Aspirin
- 3rd week infection with virus (siphilis, rubella, herpes)
5
Q
Causes of Holoprosencephaly in embryo
3
A
- 45% trisomy (X18 or X13)
- Cyclopamine as SHH antagonist on PITCH1 receptor
- Mutation of DISP1, SHH, PTCH1,GLI1
6
Q
DISP1 activates
A
Sonic Hedgehog is activated by
7
Q
Sonic Hedgehog agonises
A
PTCH1
8
Q
GLI1 is a transcription factor activated by
A
PTCH, a surface receptor
9
Q
- The major cause of mental retardation in the western world
- I/500 live births
A
Foetal alcohol syndrome
10
Q
Foetal alcohol syndrome involves
5
A
- Thin upper lip
- Rounded, indistinct philtrum
- Small Palpebral fissures
- Epicanthal folds on upper eyelid
- microcephaly and micrognathia
11
Q
Palpebral fissures
A
eyelids
12
Q
Philtrum
A
bifid structure between the septum and the lips
13
Q
A
A. neurocranium
B. Chondrocranium
C. Viscerocranium
- Auditory ossicles (maleus, incus, stapes)
- Lambdoid stuture
- Alisphenoid
- Occipital Squama
- Coronal Stuture
- Posterior Fontanelle
14
Q
Neurocranium includes
A
- Frontal
- Parietal
Intermembranous ossification
15
Q
Viscerocranium
A
- Maxilla
- Mandible
- Ear Ossicles
- Styloid Process
- Hyoid
- Laryngeal cartilages
16
Q
Chondrocranium includes
A
- Ethmoid
- Sphenoid
- Occipital
Endochondrial ossification
17
Q
Bone fomation process?
A
- Endochondrial
- Intramembranous
18
Q
Craniosynostis, common types
2
A
- Sagittal 40%
- Coronal15%
19
Q
Which malformation?
3
A
- Apert
- Crouzon
- Pfeiffer
20
Q
- Congenital craniostynosis syndrome cases / all craniostynosis =
A
~30%
21
Q
Congenital Craniostynosis syndromes and FGFR receptor mutations.
4
A
- Muenke FGFR3
- Apert FGFR2
- Crouzon FGFR3 & FGFR2
- Pfeiffer FGFR1 & FGFR2
22
Q
FGFR mutations
A
- Are dominant
- Overly high affinity for FGF
- Early ossification of intramembranous stuture
23
Q
Ectoderm -> Cleft
Endoderm -> ?
A
Ectoderm -> Pouch
Endoderm -> ?
24
Q
Ectoderm -> Pouch
Endoderm -> ?
A
Ectoderm -> Cleft
Endoderm -> ?
25
Cranial Neural crest: What parts?
1. Midbrain
2. Forebrain
3. Frontonasal Process
4. Pharyngeal arches
5. Otic Vesicle (inner ear)
26
1st Pharyngeal arch: which origins?
1. Paraxial Mesoderm
2. Cranial Neural Crest cells
27
Neural crest contributes to
6
1. Neurons and glia of the brain - which?
2. Bones of Neurocranium, Chondrocranium and viscerocranium
3. Tooth odontoblasts
4. Facial connective tissue
5. Pulmonary trunk
6. Septation of aorta
28
Pharyngeal arches
1. Frontonasal process
2. Maxilliary process
3. Hyoid Process
4. Mandibular process
5. 24 days
29
Facial Development
1. frontonasal process
2. Medial nasal plactode (of fnp)
3. lateral nasal plactode (of fnp)
4. Maxilliary prominences
5. Mandibular prominences
6. Intermaxilliary process
7. bridge of nose and philtrum
a = 6
b = 7
c = 10
30
bifid nose
result of the incomplete fusion of the medial nasal prominences
* orbital hypertelorism
* notched nasal tip or divided nostrils
* deficit in midline frontal bone
31
orbital hypertelorism
eyes are too far apart
32
Cleft lips
1. Incidence
2. Reason
3. Varieties and proportion
4. Association with cleft palate
1. 1/1000
2. Failure of maxilliary swellings to fuse with intermaxilliary process. Cause of this unclear
3. Unilateral 90%, Bilateral 10%
4. 50% concur with cleft palate.
33
Palate formation
1. Primary Palate
2. Palatine shelves
3. Maxilliary Prominences
4. Nasal septum
5. Nasal Chambers
6. Tongue
34
Primary palate
Formed by an extension of the intermaxilliary process, fusing with the palatine shelves
35
Palatine shelves
Grow medially from the maxilliary prominences
Initially grow beneath the tounge, then rise to meet at the midline above along with the nasal septum.
36
Nasal septum
Separates the left and right nasal chambers
37
Hard Palate
Formed by the endochondrial ossification of the lower half of the palate
38
Cleft palate
1. Incidence
2. Association with cleft lip
3. Causes (3)
1. 1/2000
2. 50%
* inadequate growth of palatine shelves
* palatine shelves fail to elevate above the tongue
* head excessively wide
39
Palate fusion
Occurrs during week 7-10
40
Fate of pharyngeal Cartilages
Arch 1
3
1. Alisphenoid
2. Malleus
3. Incus
41
Fate of pharyngeal Cartilages
Arch 2
4
1. Stapes
2. Styloid Process
3. Stylohyoid ligament
4. Lesser Cornu of Hyoid
42
Fate of pharyngeal Cartilages
Arch 3
2
1. Body of hyoid
2. Greater cornu of hyoid
43
Fate of pharyngeal Cartilages
Arch 4
2
1. Thyroid cartilage
2. Cricoid Cartilage
44
Fate of pharyngeal muscles
Arch 1
4
1. Temporalis
2. Masseter
3. Mylohyoid
4. Anterior Belly of digastric
45
Fate of pharyngeal muscles
Arch 2
6
1. Temporalis
2. Orbicularis Oculi
3. Orbicularis Oris
4. Auricularis
5. Masseter
6. Posterior Belly of digastric
46
Fate of pharyngeal muscles
Arch 3
1
1. Stylopharyngeus
47
Fate of pharyngeal muscles
Arch 4
1. Middle Constrictor of Larynx
2. Inferior constrictor of Larynx
3. Cricothyroid muscles
48
Pharyngeal Cleft fates
4
1. External Auditory Meatus
2. Enclosed by outgrowth of 2nd arch
3. Enclosed by outgrowth of 2nd arch
4. Enclosed by outgrowth of 2nd arch
49
Pinna
Fromed from six auricular hillocks
Three from first and three from second pharyngeal arches
50
Pharyngeal Pouches' fate
Endoderm patterns the identity of each pouch.
1. Internal Auditory tube and primary tympanic recess
2. Palatine tonsil
3. Inferior Parathyroid gland and thymus
4. Superior Parathyroid gland and ultimobranchial bofy
51
Thryroid is made from
Endoderm at the base of the pharynx
52
Treacher Collins Syndrome
1. Incidence
2. Reasons
3. Features (5)
1. 1/50,000 births
2. Growth in 1st & 2nd Pharyngeal arches is limited
3. .
* Hypoplasia of the mandible, zygomatics, outer and middle ear
* Downward slant of palpebral fissures
* Notching of the lower eyelids
* Paucity of eyelashes
* High Palate, usually cleft
53
Treacher collins incidence
Inheritance : New Mutations
4:6
54
Treacher Collins
1. Trait type
2. gene
3. Gene's protein function (3)
1. Autosomal Dominant: penetrance variable; 60% of cases the result of new mutations.
2. Caused by various mutstions in TCOF1, a gene which codes the protein "treacle"
3. Treacle is involved in ribosomal biogenesis
4. Strongly expressed in the neural folds and pharyngeal arches of embryos
5. With defective treacle, cranial neural crest sees reduced mitosis and increased apoptosis.
6. Therefore facial defects occurr due to a lack of material.
