EX3; Formation of Mandible and TMJ Flashcards
These are the initial appearances of bone tissue in the area where each of the 206 bone organs of the body form
ossification centers
How many ossification centers are in the jaw
2 maxillae (each bone) 2 mandible (each half)
In which environments do the ossification centers appear
in mesenchyme
on or within a cartilage model
What is the development of an ossification center within mesenchyme called
intramembranous bone organ development
What is the development of an ossification center on or within a cartilage model called
endochondral bone organ development
True or False
The number os ossification centers varies from bone to bone
True
What bones have endochondral ossification centers
ulna
femur
True or False
A bone will contain either a endochondral or intramembranous bone organ system, not both
False; some bones, such as the temporal bones, have both
mixed ossification centers
This is the location of the addition of bone to a bone organ
growth site
The periosteum, endostieum, aversion and volkman canals, and the PDL are all examples of what
growth sites
No matter what environment bone tissue from in/on, it always forms within what
a highly vascular connective tissue
What is another name for the highly vascular connective tissue that the bone tissue forms in
intramembraneous bone tissue
When do the 2 maxillary bones and 2 mandibular halves become one
at the end of the first postnatal year
True or False
cartilage is the model for bone and later becomes bone
False; it is resorbed, and does not become bone
This serves as the temporary skeleton of mandibular processes of branchial arch 1 and as a temporary attachment for muscles
Meckel’s cartilage
What two ear ossicles does Meckel’s cartilage become (endochondral ossification)
malleus and incus
What two ligaments does Meckel’s cartilage serve as a site for the appearance of (retrogressive changes)
anterior mallelar and sphenomandibular
Meckel’s cartilage serves as a temporary anterior lingual plate of the forming what
mandible halves
Meckel’s cartilage serves as what at the chin end of the mandibular halves
growth sites
Meckel’s cartilage undergoes growth, mineralization, and respiration while serving as anterior whats and replaced as temporary anterior lingual plates by the encroaching bone tissue of the growing mandible halves
growth sites
Meckel’s cartialge serve as both ossification centers for what and as growth site of what
ossification center = ear ossicles
growth site = mandibular half
In which weeks does the mandible begin development; the appearance of the 2 ossification centers
in the 6th embryonic week
Where does the mandible arise from
2 bilateral ossification centers within mesenchymal tissue, lateral to Meckel’s cartilage
The ossification centers of the mandible appear in the area of where
where the inferior alveolar nerve branches into the mental and incisive nerves or site of future mental foramina
In which direction does the bone of the mandible grow
anterior and posterior from the centers
in this direction, the bone incorporates the distal parts of Meckel’s cartilages; becoming the temporary lingual plate and a growth site for each mandible half
anterior
in this direction, the bone is in the from of an “U” featuring facial and lingual plates, it incorporates an independent piece of hyaline cartilage that become the condylar cartilage (another growth site)
posterior
True or False
The condylar cartilage arises from Meckel’s cartilage
False; it is independent
These appear in the 6th embryonic week within the mesenhyme lateral to Meckel’s cartilages in the area of the future mental foramen
bilateral ossification centers
The proximal end of Meckel’s cartilage serves as the model for what
malleus
incus
anterior mallelar ligament
The middle area of Meckel’s cartilage serves as the model for what
sphenomandibular ligament
The distal end of Meckel’s cartilage serves as the model for what
temporary anterior lingual plate
growth sites of the mandible halves
This is the place of union or junction between two or more bones of the skeleton
joints or articulations
This type of joint permits no mobility (fibrous and suture joints); like between maxillary bones
synarthrosis
This type of joint permits slight mobility (cartilaginous joint); like pubis symphysis
amphiarthrosis
This type of joint permits a variety of movement (synovial joint); like TMJ
diarthrosis
This refers to the TMJs dual compartment structure and function
ginglymoarthrodial joint
This is a joint that binds a tooth to a bone socket
gomphosis joint
What are the three features of most freely movable joint (like the fetal elbow)
one joint cavity
incomplete articular disc
cartilage articular surfaces
What two bones form the TMJ
squamous portion of the temporal bone condyloid process (condyle) mandible
What are the three unique features of the TMJ
complete articular disc
two joint cavities
soft connecting tissue articulating surfaces
In which week would you see blastema or rudiments of TMJ and site of condylar cartilage appearance
week 8
When does cavitation of the TMJ appear (articular disc)
third month in utero
This is a growth site of the mandible
hyaline cartilage of the condyle
Appositional growth occurs between what
articular connective tissue surface and the condylar cartilage
The condylar cartilage remains until about the age of what, when it is replaced by compact bone tissue
25
The TMJ blastema is where what structures will form
condylar cartilage
articular disc
two joint cavities
soft tissue articular surfaces
