Orofacial Development: Palate and Jaw Flashcards
three stages of primary palate formation and upper lip
- formation of inter-maxillary segment
- nasal septum of developing ethmoid
- differentiation of intermaxillary segment
during stage 1, intermaxillary segment develops due to what
fusion of medial nasal process of frontonasal region
during stage 2, how does nasal septum of ethmoid grow
inferiorly from roof of nasal cavity toward oral cavity
what are the 2 components of intermaxillary segment
- labial (philtrum of upper lip)
- palatal (primary palate containing max incisors will ossify by intramembranous)
formation of upper lip involves fusion of what regions of soft tissue
- labial component of max process
- labial part of intermaxillary segment (philtrum) (outer red)
what stage:
proliferation of neural crest derived mesenchyme (ectomesenchyme) in lateral palatal shelves of maxillary process
stage 1 prior to palatal elevation
what stage:
palatal shelves lie in vertical orientation located on either side of tongue
stage 1 prior to palatal elevation
what must happen before palatal shelves can elevate to a horizontal position
lower jaw needs to grow forward, pulling tongue downward into floor
what stage:
lower jaw grows forward, and tongue drops from nasal cavity into floor of mouth, creating room in oral cavity for shelf elevation
stage 2 - palatal shelf elevation
palatal shelf elevation depends on what
proliferation of neuralcrest derived mesenchyme (ectomesenchyme) and increased synthesis of ECM proteins
during stage 2, do palatal shelves move to a vertical or horizontal position
HORIZONTAL
does the nasal septum continue its downward growth to separate nasal cavity into 2 chambers and fuse w/ secondary palate during stage 2
YES
what stage:
bilateral fusion of palatal shelves anteriorly with primary palate (future premaxilla)
stage 3 - fusion and completion of palatogenesis
what stage:
miidline fusion of lateral palatal shelves with each other = secondary palate
stage 3 - fusion and completion of palatogenesis
fused palatal shelves fuse superiorly with ___
inferior edge of descending nasal septum
the primary and secondary palates together form what?
definitive/complete adult palate
signaling between ectoderm and ectomesenchyme is what kind of factor controlling palatal fusioin
intrinsic
what are the intrinsic factors of palatal fusion
- survival of ectomesenchyme and adequate proliferation allowing shelves to elevate and touth
- apoptosiis of ectoderm - at medial epithelial seam
- fusion/confluence of ectomesenchyme throughout completed palate
- differentiation of remaining epithelium on palatal and nasal ssurface and differentiation of bone. muscle migrates into region
growth of head and skull is what kind of factor controlling palatal fusion
extrinsic facttor
what are the extrinsic factors of palatal fusion
- downward and forward growth of mandible must occur to accomodate shelf elevation
- growth of mandible lowers the tongue out of nasal cavity and into floor of oral cavity
what is the location of a potential cleft to occur
site at which tissue merges or fuses together
what is the boundary between primary and secondary palate
incisive foramen
in order for fusion between palatal shelves to occur, what is required
breakdown/apoptosis of epithelium covering area between palatal shelves and at point of fusion with nasal septum
what does breakdown of palatal shelf epithelium establish
confluence of neural crest derived mesenchyme (ectomesenchyme)
when does ectomsenchyme begin to differentiate into bone and CT
following fusion of palatal shelves
palatal skeletal muscles are derived from what
head mesoderm
what stage:
intramembranous ossification of anterior portion of palate occurs (forms definitive hard palate)
stage 4
what are parts of hard palate
premacill, palatine process of maxiilla and palatiine bone
where does skeletal muscle differentiate in palate
posterior portion of secondary palate - muscle of the soft palate
muscles of soft palate originate from what? what is the exception?
paraxial/head mesoderm from region of 4th arch
exception: tensor veli palatini is paraxial mesoderm of 1sts arch
how many primary ossification sites are there? what are they?
1 - incisive foramen
4 - palatine foramen
how does ossification around incisive foramen occur
spreads anterolateral
how does ossification occur around palatine foramen occur
bilaterally spreads medial, anteriorly and posteriorly
what type of growth occurs at secondary growth centers
appositional growth
examples of secondary growth centers
- sutural growth
- secondary growth cartilages
- displacement growth
developmental structure and adult structred formed of:
labial intermaxillary segment
DS: intermaxillary
A: philtrum of lip - soft tissue/mucosa
developmental structure and adult structure formed of:
palatal intermaxillary segment
DS: primary palate
A: premaxilla bone (derivative of intermaxillary process)
developmental structure and adult structure formed of:
labial maxillary processes 1st PA
DS: maxillary process
A: upper lip - soft tissue/mucosa
developmental structure and adult structure formed of:
palatal component of maxillary processes 1st PA
DS: latteral palatal shelves
A: secondary palate (palatine process of maxilla, palatine bone, and soft mucosa/soft CT)
developmental structure and adult structure formed of:
upper jaw component of maxillary processes 1st PA
DS: facial skeleton/membranous viscerocranium
A: maxilla and alveolar process
The _____ will contribute to the external and internal adult structures of the mid-face and upper jaw
1st PA maxillary process
maxillary facial swelling/process is comprised of ___ covered externally with ___
ectomesenchyme; ectoderm
what do swellings/processes differentiate into
soft CT/mucosa, cartilage, bone
muscles from ___ PA contribute to lip and cheek
2nd
the ___ contributes significantly to bones of facial skeleton which support midface
1st PA maxillary process
developmental precursor, facial derivative, and adult structure of:
external structures (soft tissue)
DP: 1st PA max process
FD: 1st PA max processs
AS: cheek and upper lip
developmental precursor, facial derivative and adult structure of:
internal structures (bony, soft, tissue/mucosa)
DP: 1st PA max process
FD: lateral palatal shelves (form secondary) AND facial skeleton
AS: maxilla, vomer, inferior concha, squamous part of temporal bone
