development of face Flashcards
what is the chondrocranium?
part of neurocranium formed by endochondral ossification
what does the neurocranium develop from?
3 pairs of cartilage precursors: prechordal, parachordal and hypophyseal
where does the cartilage that makes up the neurocranium come from?
occipital somites
parachordal cartilages form _____
basioccipital
occipital somites form ____
exoccipital (modified vertebral element)
periotic capsules form _____
petrous and mastoid regions of temporal bones
hypophyseal cartilages form ____
body of sphenoid (basisphenoid)
posterior prechordal cartilage forms _____
presphenoid
alisphenoid forms ____
greater wing
orbitosphenoid and hypochiasmatic form ____
lesser wing
anterior prechordal cartilage forms ______
ethmoid bone along with olfactory capsule
modified epiphyseal growth plate allowing growth along A-P axis
spheno-occipital synchondrosis (SOS)
what allows deformation of skull as it passes through birth canal?
bones of cranial vault not completely ossified and joined by fibrous sutures
six sutures/fontanelles present at birth
anterior, posterior, anterolateral and posterolateral
how is the development of the face established?
by development and joining of 5 prominences associated with the 1st pharyngeal arch: frontonasal, 2 maxillary and 2 mandibular
prominences initially surround _____
stomodeum
separates stomodeum from GI tract
oropharyngeal membrane
further growth and expansion is dependent on _____
NCC proliferation
maxillary prominences enlarge and grow ____
ventrally and medially
form as bilateral oval thickenings on inferolateral aspect of frontonasal prominence
nasal placodes
what do the nasal placodes eventually become?
nasal pits (eventually anterior nares and nasal cavity)
horseshoes shaped elevations surrounding placodes
medial and lateral nasal processes
groove between lateral nasal process and maxillary prominence
nasolacrimal groove
medial nasal processes move toward midline and join to form _____
bridge and septum of nose
inferior tips of medial nasal process expand laterally and inferiorly to fuse as ____
intermaxillary process
intermaxillary process will give rise to _____
philtrum
primary palate
4 upper incisors
intermaxillary process fuses with maxillary prominence to form ____
upper lip
nasal pits _____ while frontonasal _____
deepen and invaginate
expands
merging of medial nasal processes into intermaxillary segment joins _____ into ____
nasal pits
single nasal sac
separates nasal sac from oral cavity
nasal fin
how does the oronasal membrane form?
apoptosis in fin expands nasal sac and thins fin
oronasal membrane ruptures to form ____
primitive choana
floor of nasal cavity is ______
primary palate from intermaxillary segment
oral and nasal cavities will be separated by formation of _____
palatal shelves
describe the formation of the palatal shelves
initially palatal shelves grow inferiorly from maxillary process
soon they rotate superiorly into horizontal position which requires deepening of mandible and descent of tongue
fusion in middle of midline and continual fusion anteriorly and posteriorly
palatal shelves form _____
secondary palate
indicates fusion of primary palate with anterior aspect of secondary palate
incisive foramen
posterior aspect of secondary palate
soft palate
how is the nasal septum formed?
down growth of medial nasal and frontonasal processes from roof of nasal cavity
describe how the nasal cavity becomes separated into two nasal passages
nasal septum eventually fuses with superior aspect of primary and secondary palates
describe primary pneumatization
maxillary, frontal and ethmoid sinuses develop as outgrowths of nasal cavity
describe secondary pneumatization
sinuses expand through childhood and adulthood
results from closure of sphenoethmoidal recess
sphenoid sinus
describe how the parotid gland develops
develops from ectoderm between maxillary and mandibular prominences
describe how sublingual and submandibular glands devleop
develop from endoderm lining floor of oral cavity
name the stages of salivary gland development
prebud
bud
pseudoglandular
canalicular
terminal bud
what types of hard tissue are teeth composed of?
enamel
cementum
dentine
what forms enamel?
ectoderm that gives rise to ameloblasts
what forms cementum and dentine?
NCCs that give rise to cementoblasts and odontoblasts
what gives rise to vasculature of teeth?
mesoderm