TMJ summary Flashcards
which part of the disc is innervated?
bilaminar zone
fct of ligaments
surround joint capsule - stability, protect against extreme movements
ligaments
lateral ligament - limits AP joint movement
sphenomandibular and stylomandibular - limit lateral movements
describe the disc
fibrocartilage
avascular
biconcave
articulating surface of condyle
fibrocartilage
articular eminence
temporal bone
dictates path of condyle during mandibular movements
glenoid cavity/fossa
hollow on inferior surface of squamous temporal zone
fibrocartilage
capsule
thin fibrous CT attached to rim of fossa and neck of condyle
disc attaches to it medially and laterally
lat aspects thickened by TM ligament
blood supply
deep auricular artery
- branch of internal maxillary artery
nerve supply
auriculotemporal, masseteric, posterior temporal nerves
superior joint compartment
gliding
protrusion, retrusion, side to side
inferior joint compartment
rotation
elevation and depression
what does the disc blend with?
anteriorly blends with LP margins
posteriorly attached to bilaminar zone - loose CT and nerves
lined with synovial membrane
suprahyoids
digastric
mylohyoid
geniohyoid
stylohyoid
infrahyoids
thyrohyoid
sternohyoid
omohyoid
sternothyroid
synovial membrane
lines non-articular surfaces
produces the synovial fluid that lubricates the joints and nourishes the cartilage
when is the joint loaded?
eating or clenching
superficial MofM
temporalis
masseter
deep MofM
LP
MP
what supplies the MofM
motor branches of V3
origin and insertion of temporalis
temporal fossa
tendon onto coronoid process
fct of temporalis
elevate (anterior vertical fibres)
retract (posterior diagonal/horizontal fibres)
origins of masseter
superficial - maxillary process of zygomatic bone
deep - zygomatic arch of temporal bone
insertion of masseter
lateral surface ramus and angle mandible
fct of masseter
elevate mandible
origins of MP
superficial - maxillary tuberosity and pyramidal process of palatine bone
deep - medial aspect LP plate (sphenoid)
insertion MP
medial surface ramus/angle
fct of MP
elevates (bilateral)
swing jaw to contralateral side (unilateral)
origins of LP
superior head - greater wing of sphenoid, roof of infratemporal fossa
inferior head - lat surface LP plate
insertion of LP
tendon - joint capsule and neck of condyle. pterygoid fovea
fct of LP
protrudes and depresses - bilateral
lateral excursions - unilateral
depressing the mandible
infra and suprahyoids act together: hyoid bone stabilised
suprahyoids contract further - pulls down on mandible
LPs contract - translates condyles down articular eminence
also assisted by gravity
= forward and downward movement of mandible
initial mouth opening
hinges from centric relation up to 25mm
- aided by supra/infrahyoid contraction
- LPs relaxed
further mouth opening
to max opening - condyle translates anteriorly (forwards and downwards) along articular eminence
- bilateral contraction of LPs and contraction of supra and infrahyoids
protrusion
condyle translates forwards and downwards along the articular eminence
bilateral contraction of LPs
mouth closing
condyle held within glenoid fossa
aided by contraction of temporalis, masseter and MP
when is the jaw most stable?
when mouth closed and teeth in occlusion
lateral excursion
mandible moves to left
left condyle pulled backwards slightly by the temporalis and rotates but sits within the glenoid fossa
R condyle moves forwards, downwards and inwards along articular eminence - R LP contracts
posterior fibres of L temporalis contract
TMD definition
collective term “a group of conditions that cause pain and dysfct in the jaw joint and muscles that control jaw movement’
- masticatory muscles
- TMJ and associated structures
- both
basic classification
disorder of the MofM
disorder of the TMJ
headache attributable to TMD
= often they co-exist
basic classification - disorder of the MofM
usually caused by parafct habits
basic classification - disorder of TMJ
disc displacement +/- reduction osteoarthritis osteoarthrosis hypermobility subluxation adhesions
Groups of TMD
Group 1 - muscle disorders
Group 2 - disc displacement
Group 3
Group 1 - muscle disorders
1a - myofascial pain
1b - myofascial pain with limitations in aperture
Group 2 - disc displacement
2a - disc displacement with reduction
2b - disc displacement without reduction and no limitations in aperture
2c - disc displacement without reduction and with limitations in aperture
soft end feel
pt guarding against opening due to pain