2/7: Anatomy of the TMJ Flashcards
What is the TMJ?
The joint where the mandible articulates with
the base of the cranium
Where does the condyle fit into?
Articular fossa
What make up the squamous part of the temporal bone?
Mandibular fossa
Glennoid fossa
Articular fossa
What is a compound joint?
More than three bones
What are the types of compound joints?
Condyle, temporal, articular disc
What does a complex joint do?
Allows more than one type of movement
What does the ginglymoid joint of the ginlymoarthroidal joint imply?
Implies hinging movement permitted
What does the arthroidal joint of the ginlymoarthroidal joint imply?
Implies gliding movement
What does the ginglymoarthroidal joint imply?
Both hinging and gliding movements
What does the synovial joint contain?
Synovial fluid
What kind of movements does the arthroidal joint have?
Translational movement
What kind of movements does the ginglymus joint have?
Rotational movements
What kind of movements does the ginglymo-arthroidal joint have?
Rotational and translational movement
What is the articular disc made of?
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?
Non-innervated and avascular
- poor reperative capacity
Is the articular disc flexible?
Somewhat flexible
What are the three sections the articular disc is divided into?
Anterior zone
Middle or intermediate zone (thinnest)
Posterior (thickest)
- posterior > anterior > middle
The articular surface of the condyle functions on the __________ zone of the disc
Intermediate
What is the TMJ disc divided into?
Medial and lateral parts
Where is the TMJ disc thicker?
Medially than laterally
What attaches the TMJ disc to the medial and lateral poles of the condyle to the surrounding capsule?
Discal/collateral ligaments
What is the articular zone of the condyle and fossa?
Most superficial layer
Made of dense fibrous CT rather than hyaline cartilage
Less susceptible to aging and better ability to repair
What is the proliferative zone of the condyle and fossa?
Contains undifferentiated
mesenchymal cells and is responsible for
proliferation of articular cartilage in response to
loads
What is the fibrocartilaginous zone of the condyle and fossa?
3D network of collagen
offering resistance to lateral and compressive forces
What is the calcified zone of the condyle and fossa?
Made up of chrondrocytes and chrondoblasts. Active site for bone remodeling.
All areas of the synovial joint are involved in?
Articulation (internal surfaces of the cavities)
What are synovial joints covered with?
Specialized endothelial cells that form the synovial lining
What do synovial joints produce? and what does this provide?
Synovial fluid (provides metabolic requirements and lubrication)
What are the two lubricants of the synovia fluid?
Boundary lubrication
Weeping lubrication
What is boundary lubrication?
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 nerves innervate the TMJ?
Mandibular branches of the trigeminal nerve (auriculotemporal and masseteric nerves)
What artery’s innervate the TMJ?
Superficial temporal artery mainly, which is
a branch of the external carotid artery
What are the two ways the disc is attached?
Posteriorly
Anteriorly
What ligament is the disc attached to?
The capsular ligament not only anteriorly, but also posteriorly, medially, and laterally
What are the posterior attachments of the disc?
Superior retrodiscal lamina
Inferior retrodiscal lamina
What does the superior retrodiscal lamina attach?
The articular disc to the tympanic plate
What is the superior retrodiscal lamina made of?
Connective tissue
lots of elastic fibers
What does the superior retrodiscal lamina do?
Stretches as joint is moved forward
What is the inferior retrodiscal lamina?
Collagenous attachment (not elastic)
What does the inferior retrodiscal lamina attach?
Posterior of disc to the posterior margin of the articular surface of the condyle
What are the anterior attachments of the disc? (Collagenous)
- superior head of the lateral pterygoid muscle (tendinous)
- superior anterior attachment
- inferior anterior attachment
What doe the superior anterior attachment attach?
– to the Capsular Ligament
– to the anterior margin of the articular surface
of the temporal bone
What doe the inferior anterior attachment attach?
– to the Capsular ligament
– to anterior margin of the articular surface of
the condyle
What are the joint cavities of the TMJ?
Superior joint cavity
Inferior joint cavity
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
What does the disc divide the joint into?
Two joint cavities
Rotation
Translation
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 TMJ?
– Collateral/Discal ligaments
– Capsular ligament
– Temporomandibular ligament
What are the accessory ligaments of the TMJ?
– Sphenomandibular ligament
– Stylomandibular ligament
What is the capsular ligament/joint capsule?
Ligament that surrounds the joint like a curtain
What is the capsular ligament/joint capsule attached to?
Attached to the base of the skull and the condyle
Attached at the periphery of the articular parts
Also attached to the disc medially and laterally
What does the capsular ligament/joint capsule retain?
Synovial fluid
What is the temporomandibular ligament?
Thickening of the capsular ligament on the lateral
aspect
What does the temporomandibular ligament extend from?
articular tubercle and zygomatic
process to the lateral pole and neck of the condyle,
and the disk
What are the two parts of the temporomandibular ligament?
– Outer oblique
– Inner horizontal
What is the function of the outer oblique part of the temporomandibular 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 temporomandibular 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?
The spine of the sphenoid bone
Where does the sphenomandibular ligament insert on?
The medial surface of the ramus of the mandible called the lingula
What is the function of the sphenomandibular ligament?
No known function in limiting mandibular movement
What does the stylomandibular movement arise from?
Styloid process
What does the stylomandibular movement insert into?
The posterior border of the ramus of the mandible
What is the function of
the stylomandibular movement?
Limits excessive protrusive movement of the mandible
