TMJ Flashcards
what is a ossification center?
initial appearance of bone tissue in the area where each of the 206 bone organs of the body form
how many adult bone organs are there?
22 including 1 mandible, 2 maxilla
what is intramembranous bone organ development?
ossification center appearing within mesenchyme
ex. mandible, maxillary bones
what is endochondral bone organ development?
ossfication center appearing on or within a cartilage model
ex. ulna, femur
what is the difference of centers from bone to bone?
number of centers vary
how many ossification center does the mandible have?
2 (1 for each half)
how many ossification center does maxillary bones have
2 ossification center for each bone
what are mixed ossification centers?
have both intramembranous and endochondrial ossification centers- such as temporalbone
what are growth sites?
addition of bone tissue to bone organ
what are the growth sites of bone tissue formation?
periosteum, endosteum, haversian and volkmann canal, pdl
what is intramembranous bone tissue?
highly vascular connective tissue that bone tissue forms within
where are meckel’s cartilage?
one in each mandibular process of branchial arch 1
what is the role of meckel’s cartilage?
temporary skeleton of mandibular processes of branchial arch 1
serve as temporary attachment for muscles that eventually attach to mandible
each cartilage serves as models for 2 ear ossicles: malleus and incus
each serve as site for the appearance of 2 ligaments anterior mallelar and sphenomandibular
serve as temporary anterior lingual plate of forming mandible halves
serve as enclosed growth sites at the chin end of the mandible halves
what is the fate of meckel’s cartilage?
from the proximal part (inner ear cavity) to the distal part (chin), each cartilage serves as sites for:
- endochondral ossification centers for 2 ear ossicles: incus and malleus
- undergo retrogressive changes becoming 2 ligaments: anterior mallelar and sphenomandibular
- undergo growth, mineralization and resorption while serving as anterior growth sites and replaced as temporary anterior lingual plates by the encroaching bone tissue of the growing mandible halves
what does meckel’s cartilage serve as?
both ossfication centers of ear ossicles and as growth site of each mandible halves
what does enclosed anterior part of meckel’s cartilage serve as?
temporary lingual plate of the mandible halves
growth site of the developing mandible halves
how is the mandible formed?
mandible develops as 2 bilateral halves that exist through the interuterine period
when does osseous union occur between the halves of mandible?
end of first postnatal year
when does the mandible begin development?
6th embryonic week
what does the mandible arise from?
2 bilateral ossification centers within mesenchymal tissue, lateral to meckel’s cartilage
where does the ossification center appear?
in the area where the inferior alveolar nerve branches into the mental and incisive nerves or the site of future mental foramina
in what direction does the bone grow from the ossification centers?
anterior and posterior
what is the anterior growth?
the bone incorporates the distal parts of meckel’s cartilages: this incorporated part of each cartilage become temporary lingual plate and a growth site of each mandibular half-toward the midline of the chin where the 2 halves approach each other
what is the posterior growth?
the bone is in the form of a “U” featuring facial and lingual plates; the posterior end of the facial plate incorporates an independent piece of hyaline cartilage that becomes “condylar cartilage”- another growth site of each mandible half -grows posterior to the site of the future tmj
