TMJ Flashcards
What is the temporomandibular joint (TMJ)?
joint where the mandible articulates with the base of the cranium
What do the condyles of the mandible fit into?
articular fossa
What fossa on the squamous part of the temporal bone are related to the TMJ?
mandibular fossa
glenoid fossa
articular fossa
What separates the condyle of mandible and squamous part of the temporal bone in the TMJ?
articular disc
What is the mediolateral length of the condyle of mandible compared to the anteroposterior width?
ML is twice as long
What is a compound joint?
- more than three bones
What are the three parts of the TMJ compount joint?
condyle
temporal
articular disc
What is a complex joint?
allows for more than one type of movement
What is a synovial joint?
contains synovial fluid
What is a ginglymoarthrodial joint?
hinging movement (ginglymoid)
and
gliding movement (arthrodial)
What type of movement does the arthrodial joint allow for?
translation movement only
- gliding
What type of movement does the gingylmus joint allow for?
rotational movement only
- hinging
What type of movement does the gingylmoarthrodial joint allow for?
rotational and translational
What is the articular disc made of?
fibrous connective tissue
What type of joint is the TMJ?
- compound joint
- complex joint
- gingylmoarthrodial joint
What is the shape of the articular disc?
inferior part - concave
superior part - concavo-convex
What are the characteristics of the articular disc?
non-innervated
avascular
somewhat flexible
dense fibrous connective tissue
What are the three sagittal sections of the articular disc?
anterior zone
middle/intermediate zone
posterior
What is the order of the sagittal sections of the articular disc from thickest to thinnest?
posterior > anterior > middle
Articular surface of the condyle functions on the _____________ zone of the disc
intermediate
What are the frontal sections of the articular disc?
medial and lateral
Is the articular disc thicker medially or laterally?
medially
What attaches the articular disc to the medial and lateral poles of the condyle?
discal/collateral ligaments
What are the histological zones of the articular surfaces in the TMJ?
- articular zone
- proliferative zone
- fibrocartilaginous zone
- calcified zone
What are the characteristics of the articular zone of the articular disc?
- dense fibrous connective tissue
- most superficial layer
- less susceptible to aging
- better ability to repair
What are the characteristics of the proliferative zone of the articular disc?
- undifferentiated mesenchymal cells
- responsible for proliferation in response to loads
What are the characteristics of the fibrocartilaginous zone of the articular disc?
- 3D network of collagen
- resistance to lateral and compressive forces
What are the characteristics of the calcified zone of the articular disc?
- chondrocytes
- chondroblasts
- active site for bone remodeling
What are the areas of a synovial joint that aren’t involved in articulation covered in?
specialized endothelial cells that form the synovial lining
What does synovial fluid provide?
metabolic requirements and lubrication
What is weeping lubrication of synovial fluid?
articular surfaces absorb some of the fluid, increased absorption during function, metabolic exchange
What is boundary lubrication of synovial fluid?
movement of fluid from one area of the joint cavity to another, prevents friction
What nerve innervates the TMJ?
mandibular branches of the trigeminal nerve (auriculotemporal and masseteric)
What artery supplies the TMJ?
superficial temporal artery (branch of the external carotid artery)
What are the articular disc attachments?
- posterior (superior retrodiscal lamina, inferior retrodiscal lamina)
- anterior (SH lateral pterygoid, superior anterior attachment, inferior anterior attachment)
- capsular ligament (anterior, posterior, medial, lateral)
What are the posterior attachments of the artiuclar disc?
superior retrodiscal lamina
inferior retrodiscal lamina
What are the characteristics of the superior retrodiscal lamina?
- to the tympanic plate
- connective tissue
- elastic fibers
- stretches as joint is moved forward
What are the characteristics of the inferior retrodiscal lamina?
- collagenous attachment (not elastic)
- to the posterior margin of the articular surface of the condyle
What are the anterior attachments of the articular disc?
- superior head of the lateral pterygoid
- superior anterior attachment
- inferior anterior attachment
What are the characteristics of the superior anterior attachment?
- to the capsular ligament
- to the anterior margin of the articular surface of the temporal bone
What are the characteristics of the inferior anterior attachment?
- to the capsular ligament
- to the 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
Which joint compartment of the TMJ does rotation occur in?
inferior joint compartment
Which joint compartment of the TMJ does translation occur in?
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 are the characteristics of the capsular ligament?
- Ligament that surrounds the joint like a curtain
- 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
- Retains synovial fluid
What are the characteristics of the temporomandibular ligament?
- thickening of the capsular ligament of the lateral aspect
- from articular tubercle and zygomatic process to the lateral pole and neck of the condyle and disc
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
- translation of the mandible after 20-25 mm
What is the function of the inner horizontal part of the temporomandibular ligament?
- limits posterior movement onto the highly innervated retrodiscal tissue (PAIN)
- prevent excessive overextension of the lateral pterygoid muscle
What are the characteristics of the sphenomandibular ligament?
- from the spine of the spheniod bone
- inserts onto the medial surface of the ramus of the mandible (lingula)
What are the characteristics of the stylomandibular ligament?
- from styloid process
- inserts into the posterior border of the ramus of the mandible
- limits excessive protrusive movement of the mandible
What is the origin and insertion of the sphenomandibular ligament?
O: angular spine of sphenodi bone
I: mandibular lingula
What is the origin and insertion of the stylomandibular ligament?
O: styloid process
I: angle of mandible
How long is the mediolateral length of the condyle of mandible?
15-20 mm
How long is the anteroposterior width of the condyle of mandible?
8-10 mm