Growth development of craniofacial structure 2 Flashcards
describe how the maxilla grows in width (before 7 years of age)
by the process of secondary displacement following brain and cranium (median palatine suture)
how does the presence of a cleft palate affect the growth of the maxilla?
there will be no growing madial palatine suture therefore the maxilla will be narrow
describe the growth of the maxilla (width ) after 7 years of age.
=occurs by bone drift (bone deposition on outer surface and resorption on inner surface [zygoma , zygomatic archs , orbits , nasal walls , lateral maxillary surface ])
=remodeling also plays a role as
orbit:
bone is resorbed from the lateral surfaces and deposited on the medial surfaces
zygomatic bone :
resorption on anterior surface and deposition on posterior surface casues posterior movement of zygomatic bone (drift )
+ deposition on lateral surface and resorbtion of medial surface
what is the most prominent growth of the maxilla?
growth in height
describe the growth in maxillary height before 7 years of age .
growth due to secondary displacement downwards to anterior cranial base and nasal cartilage
describe maxillary growth in height after 7 years of age :
growth by drift : resorption of nasal floor and deposition on palate and alveolar process ( V principle )–inverted V–
what direction does the alveolar process grow in ?
downward forward and lateral
how are the alveolar ridges affected as teeth erupt ?
apposition [+] that’s why when some teeth don’t erupt , the alveolar ridges aren’t developed enough and the maxilla lacks in height
describe the growth in depth of the maxilla before 7 years of age :
bone deposition at zygomatico maxillary(zygomatico temporal), frontomaxillary (frontonasal) and pterygo palatine sutures —> allows maxilla to grow downward and forwards
all these sutures are oblique and parallel to each other
describe growth in depth of maxilla after 7 years of age :
drift: resorbtion of anterior border and deposition of posterior border—-> primary displacement causing maxilla to move forward due to growth of tuberosity and antrum
primary displacement of maxilla causing increase in depth is due to :
-growth of tuberosity
-enlargement of maxillary antrum
resorption occurs on entire wall of maxillary sinus except medial wall and outer surface deposition causing increase in antrum size
which brachial arch is the mandible derived from ?
1st brachial arch ( mandibular arch)
the majority of mandible ossification is :
intramembranous ossification adjacent to Meckel’s cartilage . endochondral ossification is also present tho
what are the 3 cartilages that are ossified by endochondral ossification ?
-condylar cartilage
-coronoid cartilage
-symphyseal cartilage
which cartilage is involved in mandibular growth up until the 20th year of life?
condylar
which cartilage converts into the mental ossicles in the symphysis region of mandible ?
symphyseal cartilage
what is the fate of the meckels cartilage ?
-malus and incus of middle ear
-Sphenomandibular ligament
-lingula as bony specule at entrance of inferior alveolar canal
-mental ossicles
describe the mandible at birth :
ill defined body
-no alveolar process
-short rami
-condyles are not well developed
-175 degree angle
angle of mandible at birth ?
175 degrees
how does the mandible grow in width ?
-through symphysial cartilage growth
-increase in inter-ramial width by resorption of its outer surfaces and deposition at inner surface (V principle)
-growth of mandibular condyles in a posterior, superior, and lateral direction by ENDOCHONDRAL bone formation (V-principle)
which type of bone formation allows mandibular condyles to grow?
endochondral
APPOSITION [+] - In the lingual side the border between the ramus & body forms Lingual tuberosity
RESORPTION [-]- Below the lingual tuberosity forms Lingual fossa
how does the mandible grow in length ?
secondary displacement downwards and forwards by action of brain and cranial base
primary displacement downwards and anterior by condylar growth in upward and posterior direction
what are the 3 mechanisms involved in condyle growth ?
-deposition above the condyle head
-deposition within the articular fossa
-due to soft tissue growth around the mandible
angle of mandible at adolescence , adulthood , and old age:
140–>110/120—>140
growth of ramus happens through :
APPOSITION [+] - Posterior border
RESORPTION [-] -Anterior border
The Ramus drifts posteriorly the entire length of the mandible body increases to accommodate posterior teeth.
growth of coronoid process :
Apposition [+] Posterior border ,apex & medial aspect
Resorption [-] Anterior border
Due to above events the Coronoid process attains shape like ‘PROPELLAR TWIST’
growth of the chin :
Develops as a separate sub unit.
APPOSITION[+] -Anterior & inferior most part forms the chin.
RESORPTION[-]-Anterior superior part of the symphysis
Downward & Forward Growth of the Mandible also contributes to increase CHIN PROMINANCE
how does the mandible grow in height?
Alveolar bone growth along the superior border of the mandibular body in the vertical direction allowing eruption of teeth.
Bone is deposited along the entire inferior surface of the mandibular body.
Chin : bone deposition at periosteal bone and resorption above mental protuberance
parts of mandible derived from intramembranous ossification:
Whole of body except anterior part
Ramus as far as mandibular foramen
describe the differential growth of the mandible :
in fetal life:
-at 8 weeks , the mandible grows faster thean maxilla
-at 11 weeks they are equal
-at 13-20 weeks the maxilla grows faster than mandible
at birth the mandible is retrognathic— early postnatal life becomes orthognathic
