TMJ Anatomy/Common Presentations Flashcards
Describe the structure of the disc of the TMJ:
biconcave fibrocollagenous structure between mandibular condyle and mandibular fossa of temporal bone
Anterior attachment of disc of TMJ:
Anteriorly attached to anterior capsule and lateral pterygoid
Posterior attachment of disc of TMJ:
Posteriorly attached to retrodiskal laminae - pulls disc back when lateral pterygoid muscle relaxes
Lower portion of joint capsule attaches what to what?
mandibular condyle to disc
Upper portion of joint capsule attaches what to what?
attaches disc to temporal bone
The TMJ is thin where?
posteriorly and anteriorly
The TMJ is thick where?
laterally and medially (collateral ligaments)
Describe movement in TMJ in first half of motion:
roll first half of motion in lower joint
Describe movement in TMJ in second half of motion:
glide in upper joint
Function of the TMJ disc:
- Separates joint cavity into two functional components
- Upper joint is a plane gliding joint for translation of mandible condyles
- Lower joint is a hinge joint that permits rotation of condyles - Force dispersion
What are the 2 layers of the retrodiscal laminae?
- Upper retrodiscal lamina
- Inferior layer curve behind the condyle & attach to capsule
Function of retrodiscal laminae?
- Stabilize the disk
- Prevents excessive translation of the disc over the condyle
- With anterior dislocation of the disc, the highly innervated laminae may be approximated between the mandibular condyle and mandibular fossa
Tempromandibular Ligament -
Function?
Counters what?
- Thickening of anterior joint capsule from neck of mandible to zygomatic arch
- Helps prevent posterior dislocation of the joint
- Prevents medial slippage of disc
- Counter lateral pterygoid pull
Temporalis:
Origin -
Insertion -
Action -
- Origin: temporal fossa
- Insertion: coronoid process on anterior ramus of mandible
- Action: elevate mandible (mouth closing)
Masseter:
Origin -
Insertion -
Action -
- Origin: Inferior and medial zygomatic arch
- Insertion: coronoid process of lateral ramus of mandible
- Action: elevation and protrusion of mandible
Medial Pterygoid:
Origin -
Insertion -
Action -
- Origin: medial surface of lateral pterygoid plate, pyrymidal process of palatine bone, tuberocity of maxilla
- Insertion: medial aspect of mandibular ramus
- Action: elevate and protrude mandible
Lateral Pterygoid:
Origin -
Insertion -
Action -
- Origin: superior head to lateral surface of greater wing of sphenoid bone, inferior head to lateral surface of lateral plate
- Insertion: neck of mandible, articular disc, TMJ capsule
- Action: protrude and depress mandible (open), lateral deviation of mandible (unilaterally)
Infrahyoid muscles:
Innervation -
Action -
Innervation - C1-C3
Action - Depress hyoid
Suprahyoid muscles action -
Elevates hyoid
Digastric action -
depresses mandible against resistance and elevates hyoid
Mandibular nerve:
Sensory -
Motor -
- Branch of trigeminal
- Sensory: teeth, temporal region, external auditory meatus, tympanic membrane, lower lip, lower face, mucosa anterior 2/3rds of the tongue, floor of oral cavity
- Motor: muscles of mastication
T/F During first 50% of motion of TMJ opening the disc remains stationary.
True
What occurs to disc during last 50% of TMJ opening?
- Disc pulled anteriomedially by lateral pterygoid
- Disc slides along with condyle