formation of Mandible and TMJ Flashcards
what is an ossification center
the intial appearance of bone tissue in the area where each of the 206 bone organs of the body form
where do ossification centers form
within mesenchym
on/within cartilage
intramembranous bone organ development
when an ossification center begin in the mesenchyme
Endochondral bone organ development
When an ossification center begins in the cartilage modl
ossification of the mdanible and maxillae
1 mandible
2 maxillae of the 22 adult skull bone organs
are the number of ossification centers the same for each bone
Vary from bone to bone
ossification centers for the mandible
2 ossification centers (1 for each halve)
ossification centers for the 2 maxillary bones
2 ossification centers for each bone
what kind of ossification centers does the mandible and maxilla have
intramembranous
mixed ossification centers
when both intramembraneous and endochondrial ossification centers
GRowth sites
addition of bone tissue to a bone organ
what are the growth sites of bone tissue formation
the periosteum
the endosteium
haversian and volkman canals
PDL
what does all bone tissue envirnoment have in common
always forms within a highly vascular connective tissue refered to as intramembranous bone tissue (not to be confused with intramembrane ossification ceneters)
where is the paired Meckel’s cartialge
One in each mandibular process of branchial arch I
skelletal roll of Paired mechel’s cartilage
temporary skeleton of mandibular processes of branchial arch I
muscular roll of paired meckel’s cartilage
serve as temporary attachment for muscles that eventually attach to the mandible
what does meckel’s cartilage serve as a model for
Malleus
Incus
what ligaments form from the paired meckel’s cartialge
anterior mallelar
Sphenomandibular
what does the Meckel’s cartialge do for the mandibular halves
serve as temporary antetrior lingual plate of the mandible halves
serve as enclosed growth sites at the chin end of the mandible halves
the proximal and distal parts of the paired meckel’s cartilage
prox: inner ear cavity
Distal: chin
what happens to the proximal end of paired meckel’s cartilage
endochondral ossification centers for the incus and malleus
what happens to the middle portion of paired meckel’s cartilage
undergo retrogressive changes to become the anterior mallelar and sphenomandibular
what happens to the distal portion of paired meckel’s cartialge
undergo growth, mineralization, and resporption while serving as anterior growth sites
replaces as temporary anterioer lingual plates by encroaching bone tissues oft he mandible halves
Ossification center and growth sites of MEckel’s cartilage
Ossification centers: ear ossicles
Growth sites: each mandible halve
Roll of the enclosed anterior parts of meckel’s cartilage
temporary lingual plate of the mandible halves
GRowth site of the developing mandible halves
when does the mandible go from 2 bilateral halves to 1 bone
when osseous union occures between the halves at the end of the first postnatal year
when does the mandible begin development
in the sixth embryonic week
what does the mandible arise from
2 bilateral ossification centers within mesenchymal tissue
lateral to meckel’s cartialge
where do the ossification centers of the mandible arise
appear in the area where the inferior alveolar nerve branches into the mental and incisive nerve (site of the muture mental foramina
direction of bone growth in the mandible
anterior and posteior
antior growth of the mandible does what to meckel’s cartialge
incorporativees the distal parts of meckel’s cartialges to bceome the temporary lingual plate and a growth site of each mandible halves
what happens to the posterior growth of the manible
the bone is in the form of a U featuring facial and lingual plates
what happens to the posterior end of the facial plate of the manible
incorporates an independent piece of hyaline cartialge to bcome condylar cartilage
Condylar cartialge
another growth site of each mandible half
Does condylar cartialge arise from meckel’s
NOPE
what kind of ossification center is the mandibular halves
Intramembranous
what do the incorporated distal ends of meckel’s cartilage serves as
Temporary anterior lingual plates and growth sites of the forming mandible halves
what does the proximal end of each meckel cartialge become
mdoel for maleus and incus ossicles
Anterior mallelar ligament
what does the middle of each meckel cartilage become
sphenomandibular ligament
what does the distal end of the meckel’s cartialge become
temporary anterior lingual plate
growth site of the madnible havles
what happens to the distal half of meckel’s cartilages
Starts to become enclosed
MC mineralized, resorbed, repalced bone tissue to form the anterior lingual plate of the mandible
when does osseus union of the mandible complete
at the end of the first year (suture disappears - remodeled to become 1 bone)
what are joints/a and articulations
the plcae of union/junctions between 2 or more bones of the skeleton
synarthrosis joint
permits little to no mobility
types of synathrosis joint
fibrous and suture joints
amphiarthrosis joint
permits slight mobility
type of amphiarthrosis joint
cartilaginous joints
diarthrosis joints
permits a cariety of movements
type of diarthrosis
synovial joints
what types of joint is between maxilary bones or temporal and paretal bones
synarthrosis
what type of joint is between the pubis symphysis
amphiarthrosis
what type of joint is the TMJ
Diarthrosis
Ginglymoarthrodial joint
dual compartment strucutre and function as ginglymo and arthrodial
Joint that binds a tooth to a bone to socket
Gomphosis joint
cavity of fetal elbow
1 joint cavity
articular disc of fetal elbow
imcomplete articular disk
surface of fetal elbow joint
cartilage articular surfaces
do features of most free moveing joints(elbow) apply to the TMJ
No
Bones of the YMJ
temporal (squamous portion)
Mandible (condyloid process)
unique features of the TMJ
complete articular disc
2 joint cavities
soft connective tissue articulating surfaces
cavitiation of the TMJ in the Blastema area at 8 week embryo
No cavitation
articular disk of the blastema area of the TMJ in the 8 week embryo
articular disk is present but cavitiation is not evident
when does cavitation of the TMJ occur
3rd month in utero
what part of the joint cavity cavitates frist at 3 months IU
lower joint cavity
what is the hyaline cartialge of the condyl
growth site of the mandible
where does appositional growth occur in the mandible
between the articular connective tissue surface and the condylar cartialge
what happens at the lower end of the hyaline cartialge of the condyle
cartilage is mineralized, resorbed and replaced by bone tissue
when does the condylar cartilage become replaced
remains until 25 years old then replaced by compact bone tissue
what replaces condylar cartialge
compact bone tissue
what covers in the conylar compact bone in the Adult TMJ
fibrous articular disc and the soft fibrous connecive tissue
when do the 2 ossification centers of the mandible form
6 week IU
when does osseous union of mandiular havles occur
end of 1st year
what does the appearance of blastema (rudiments) of the TMJ occur
8th week IU
when does cavitiation within blastema of TMJ occur
3rd month IU
when is the condylar cartialge replaced by compact bone
25th year
what is the blastema
rudimentary (embryonic) substance from which cells, tissues, or organs are formed
what does the TMJ blastema from
condylar cartialge
articular disc
2 joint cavities
soft tissue articualr surfaces
what kind of ossification does the mandible and mxila do
intramembranous
