Face and Palate Flashcards
time of development of the face
4-8 weeks in utero
- eyes, ears, nose
time of formation of palate
6-10 weeks in utero
- soft palate developing till 12 weeks
what is the earliest bone laid down in the skull
the mandible (approx 6-7 weeks)
one of the earliest in the skeleton
what are the 2 severities of defects in face and palate formation
can be major defects
- are incompatible with life
can be minor defects
- can be surgically corrected
the process of face and palate formation is
Highly coordinated and pre-programmed
how common are face and palate development abnormalities
1 in 700 births have some form of congenital malformation
More severe defects tend to occur 4-8 weeks (early facial developments)
Relatively minor problems develop later (8-12 weeks)
- Cleft lip and palate
what do the frontal nasal processes develop from
tissues surrounding forebrain
Develop separately from 1st pharyngeal arch (tissue around maxilla and mandible)
- Usually defects affect one or the other but not both at the same time
what are pharyngeal arches
ridges/outgrowths of tissues
devolved from gills of fish
- common in embryogenesis of all vertebrates
pharyngeal arches in humans
4 pairs of well developed arches
- 5 is short ridge
- 6 is debatable
Mesenchymal core (mesoderm and neural crest) covered ectoderm, separated by clefts and inside has endoderm separated by pouches
Each arch has a central rod of pre-cartilaganous/ cartilaginous mesenchyme then transformed into adult skeletal structures
- Striated muscles transformed into muscles of face
Each arch supplied by major artery and has specific CN nerve derived from
pharyngeal arch structure
Mesenchymal core (mesoderm and neural crest) covered ectoderm, separated by clefts and inside has endoderm separated by pouches
Each arch has a central rod of pre-cartilaganous/ cartilaginous mesenchyme then transformed into adult skeletal structures
- Striated muscles transformed into muscles of face
Each arch supplied by major artery and has specific CN nerve derived from
1st pharyngeal arch
Mandibular
Trigeminal Nerve CNV, Muscles of Mastication, Malleus, Incus, Meckel’s Cartilage
- Forms mandible
- – Second bone to start to ossify in skeleton
- — Intramembranous ossification – bone laid down in mesenchyme around it
Mandibular, part maxilla, ear
2nd pharyngeal arch
facial nerve CNVII, muscles of facial expression, hyoid
3rd pharyngeal arch
glossopharyngeal Nerve CNIX, Stylopharyngeus, Common Carotid Artery, Hyoid
4th and 6th pharyngeal arches
Vagus Nerve CNXII, Muscles of Pharynx and Larynx, Aortic Arch, Laryngeal Cartilages
how many prominences does the face develop from
5 prominence surrond stomadaeum
grow and develop and fuse in midline to form face
what is the stomadaeum
central depression in developing skull which leads on to be the mouth
what are the 5 prominences of facial development
frontnasal
- overlies developing forebrain
paired maxillary
- from 1st pharyngeal arch
paired mandibular
- from 1st pharyngeal arch
what does the frontal nasal prominence develop into
Forehead; bridge of nose
- Lateral aspects – circles – nasal placode
Grow and enlarge in fifth embryonic week
Olfactory epithelium
what does the medial nasal prominence develop into
Midline nose (grow towards midline and form septum)
philtrum upper lip (fuse with maxillary prominences that are going towards midline)
what does the lateral nasal prominence develop into
Alae (wings/lateral aspect) of nose (fuse to form)
what does the maxillary prominence develop into
Cheeks
lateral upper lip (corners of mouth – where fuse with mandibular prominence)
what does the mandibular prominence develop into
Lower lip and jaw (fuse in midline, location where they fuse – chin can lead to cleft or dimple in chin not fused)
what forms the nasal lacrimal duct and lacrimal sac
6th week – groove between lateral nasal prominence and maxillary process
what term is used for the precursor of the ear
auricular helix
how many parts does the palate form from
2
process of developing palate (5)
at 6 week the nasal and oral cavities are continuous
- open space
end of 7 weeks – Medial nasal processes expand inferiorly to join to form form intermaxillary process
- gives rise to philtrum of lip and primary palate
- –contains 4 incisor teeth
- —premaxilla
palatal shelves (7-8 weeks) separate them - derive from Maxillary prominences, from 1st Pharyngeal arch (lateral palatal shelves form secondary palate)
Thin palatal shelves grown downwards from maxillary prominences (approx. 7 weeks)
- Then rotate up towards midline – go horizontal
- –Fuse around midline
- —Can see primary palate (premaxillary) and secondary palate
- —Maxilla and palatine bones laid down in tissue
Growth and expansion of mandible to accommodate tongue
basics of how nasal septum formed
Downgrowths of frontal nasal prominence
- Fuse in midline
Divide into L and R nasal cavities
stomadaeum
Primitive mouth
Structure 5 prominences form around
medial nasal prominences develop into
philtrum of upper lip and tip of nose
what forms the alae of nose
maxilla fused with lateral nasal prominences
5 prominences of facial development and 2 additional features used to show stage
frontal nasal prominence
mandibular prominence
maxillary prominence
medial nasal prominence
lateral nasal prominence
nasal pits and developing eye
what do the lateral palatal shelves come from
maxillary process
- open space between them can see into nasal cavity from oral cavity
what fuse to form the inter-maxillary process (distal to the primary palate)
medial nasal processes
stages in palatine development
palatal shelves grow down, towards you
palatal shelves begin to fold up horizontally
- coming closer together
palatal shelves nearly at midline
palatal shelves start to fuse in midline
- incisive foramen where they fuse together towards the primary palate/premaxilla region
where could palatal development go wrong
fusion not occur
- cleft palate
can be linked to mandible growth as it’s growing simultaneously
complete or partial failure of facial development can lead to
facial cleft
facial cleft affecting one side
unilateral
facial cleft affecting both sides
bilateral
4 impacts of life facial clefts can impact
Feeding
Speech
Hearing
Social integration
how common is facial clefts
1 in 700 births
can be connected to a syndrome (300 syndromes) most oro-facial clefts are not
cleft lip
Failure of fusion of maxillary prominence with the mesial nasal processes
- Maxillary prominence coming in to form the secondary palate
- Medial nasal process forms the primary palate and philtrum of lip
- -See cleft formed in between
Uni or Bi lateral
Can extend to incisive foramen
medial cleft lip
Failure of the two medial nasal processes to fuse with each other
- rare
cleft palate
Failure of 2 palatal shelves fuse together in midline
what can effect the distribution of cleft lip and palate
sex, familial distribution, geography
isolated cleft lip prevalence
more common on left
more prevalent in males
isolated cleft palate prevalence
more in females
- later elevation of palatal shelves in females (week 8 over 7)
cause of oro-facial clefts
Multi-factorial
- Identical twins don’t form the same
Related factors
- Environment
- Smoking
- Alcohol
- Viral infection
- Certain drugs
- Some vitamin A analogues
diagnosis of cleft lip
ultrasound from week 13
usually picked up in 20 week midterm scan
- and definitely picked up 72hrs post-partum
diagnosis of cleft palate
harder to see on ultrasound pre birth
treatment of cleft lip and palate
Can be repaired surgically
cleft lip surgery
- 3-6 months
cleft palate surgery
- 6-12 months
advise on cleft lip/palate treatment
Advised early on
- Feeding issues – unable to form seal
- Hearing issues – higher ear infections chance
- Dental development – can have impact
- Speech development
time of cleft lip surgery
3-6 months
time of cleft palate surgery
6-12 months
additional treatment that might be required for cleft lip and palate babies (2)
Speech and language therapy
Orthodontic treatment
depending on the development of adult dentition
sutures
joints between bones in skull
- juvenile further apart
strong fibrous joints
limited to no movement
ossification of bones of calvarium
intramembranous ossification
intramembranous ossification
laid down directly into membrane
grow and start to replace the membranes
fontanelles
membrane tissue remains (yet to be ossified)
movement/flexibility can happen here
- will continue to grow and replaced by sutures
- – fibrous bone connections
mental symphysis
2 forming sides of mandible
can start to fuse but see split still
closed mental symphysis
single mandible
symphysis completely closed
- one mandible
by one year old
open mental symphysis
see 2 parts of mandible
visible split in middle
what can happen to sutures with advanced age
Sutures can fuse completely and disappear
antemortem tooth loss
Evidence of healing
Tooth sockets filling in, alveolar bone removed with tooth
post mortem tooth loss
No healing/turnover of bone
Open tooth socket
denture pain if most alveolar bone is lost
dentures sit close to mental foramen
- sit on nerve = pain
bone in life
Constant turn over
- Old removed
- New laid down
Micro fractures repaired
Don’t use it you lose it
- Astronauts/bed ridden lose bone density and resor
No mechanical stimulation as loss of teeth
- Alveolar bone resorbed
why wide obtuse angle of mandible in juvenile
Wide obtuse angle in juvenile
- Ramus not finished growing
Need to widen to accommodate adult dentition
- To create space for developing adult teeth
angle of mandible comparison between males and females
females More obtuse than males
Changes in puberty - Males undergo larger growth spurt -Larger muscle mass ----Pull more on bone More robust mandible
Mandible grows more in men
- Square chin and jaw
- Ridges on bone due to enlarge muscles of mastication
