Lecture 5- anatomy of the TMJ Flashcards
what is the TMJ
where the mandible articulate with the base of the cranium
what does the condyle of the mandible fit into
squamous part of the temporal bone- manidbular fossa, glenoid fossa, articular fossa
what is a compound joint and what are the bones of the TMJ
more than three bones
-condyle, squamous temporal, articular disc
what is a complex joint
allows for more than one type of movement
what is the joint classification of the TMJ
compound joint
-complex joint
-synovial joint
-ginglymoarthrodial joint
what is meant by ginglymoarthrodial joint
-ginglymoid joint implies hinge movement
-arthodial joint implies gliding movement
- so hinging and gliding
what is the articular disc made of
dense fibrous connective tissue
what is the shape of the articular disc
concave on the inferior part
- concavo-convex on the superior part
is the articular disc innervated or have blood
no
is the articular disc flexible
somewhat
what are the 3 sections of the articular disc in a sagital section
-anterior zone (middle in thickness)
- middle or intermediate zone (thinnest)
- posterior (thickest)
what does the articular surface of the condyle function as
the intermediate zone of the TMJ disc
what is the articular disc divided into in a frontal section
medial and lateral
which portion is thicker: medial or lateral
medial
what do the discal/collateral ligaments attach the disc to
the medial and lateral poles of the condyle and the surrounding capsule
what is the articular zone made of histologically and what is its purpose
dense fibrous connective tissue, less suscpetible to aging and better ability to repair, most superficial layer
what is the proliferative zone made of histologically and what is its purpose
undifferentiated mesenchymal cells and is responsible for proliferation of articular cartilage in response to loads
what is the fibrocartilaginous zone made of and what is its purpose
3D network of collagen offering resistance to lateral and compressive forces
what is the calcified zone made of and what is its purpose
chondrocytes and chondroblasts
-active site for bone remodeling
what are all areas of the synovial joint not involved in articulation covered with
specialized endothelial cells that form the synovial lining
what do specialized endothelial cells that form the synovial lining produce
synovial fluid
what is boundary lubrication and what does it do
movement of fluid from one area of the joint cavity to another
-prevents friction
what is weeping lubrication
articular surfaces absorb some of the fluid
- increased absorption during function metabolic exchange
what is the innervation of the synovial joint
mandibular branches of the trigeminal nerve- auriculotemporal and masseteric
what is the vascularization of the synovial joint
superficial temporal artery - branch of the external carotid artery
what are the disc attachments
-posteriorly
-anteriorly
-attached to capsular ligament anteriorly, posteriorly, medially, and laterally
what are the posterior attachments of the disc
-superior retrodiscal lamina
- inferior retrodiscal lamina
describe the superior retrodiscal lamina
-attaches the articular disc to the tympanic plate
-connective tissue
- lots of elastic fibers
- stretches as joint is moved forward
describe the inferior retrodiscal lamina
-collagenous attachment (non elastic)
- attaches the posterior margin of the articular surface of the condyle
what are the anterior attachments of the disc
-superior head of the lateral pterygoid muscle
-superior anterior attachment
- inferior anterior attachment
what does the superior anterior ligament attach
-to the capsular ligament
- to the anterior margin of the articular surface of the temporal bone
what does the inferior anterior attachment attach
-to the capsular ligament
- to anterior margin of the articular surface of the condyle
what is the superior joint cavity bordered by
-glenoid fossa
- superior aspect of the disc
what is the inferior joint cavity bordered by
-inferior aspect of the disc
- superior aspect of the condyle
where does rotation occur
in the inferior joint compartment
where does translation occur
in the superior joint compartment
what are the functional ligaments of the joint
-collateral/discal ligaments
-capsular ligaments
- TMJ ligament
what are the accessory ligaments
-sphenomandibular ligament
- stylomandibular ligament
what is the capsule ligamnet/joint capsule attached to
-the base of the skull and the condyle
- the periphery of the articular parts
- the disc medially and laterally
what does the capsular ligament do
surrounds the joint like a curtain
- retains synovial fluid
where is the TMJ ligament
-thickening of the capsular ligament on the lateral aspect
-extends from the articular tubercle and zygomatic process to the lateral pole and neck of the condyle and the disc
what are the two parts of the TMJ ligament
-outer oblique
- inner horizontal
what is the function of the outer oblique portion of the TMJ ligament
-prevents over rotation of the mandible
-causes translation of the mandible after 20-25 mm opening
what is the function of the inner horizontal part of the TMJ ligament
- limits posterior movement onto the highly innervated retrodiscal tissue (PAIN)
- prevents excessive overextension of the lateral pterygoid muscle
what does the sphenomandibular ligament arise from and what does it insert into
the spine of the sphenoid bone inserts onto the medial surface of the ramus of the mandible called the lingulua
where does the stylomandibular ligament arise from and insert
arises from the styloid process inserts into the posterior border of the ramus of the mandible
what is the function of the stylomandibular ligament
limits excessive protrusive movement of the mandible
what is centric relation dependent on
TMJ not teeth
