TMJ Disorders (Dr Naudi) Flashcards
What type of joint is the TMJ
synovial
What encloses the TMJ
A fibrous joint capsule completely encloses the TMJ
Where is the disc located
The fibrous disc is located between the temporal bone and the mandibular condyle on each side
What does the disc allow
- articulation between the two bones
- seperation of the TMJ into two compartments
What do the membranes that line the TMJ secrete
synovial fluid
What does the synovial fluid do
fills the synovial space + lubricates teh joint
What is the TMJ innerated by
CN5
branches of mandibular nerve
auriculotemporal nerve
How can someone confuse TMJ pain with ear pain
auriculotemporal nerve supplies the EAM
can result in TMJ pain being confused with an ear infection
Where does the TMJ blood supply originate from
external carotid artery with the first branch of the maxillary artery supplying the TMJ
What is the name of the artery that supplies the TMJ
Deep auriclar artery
Which part of the disc is not innervated
anterior band
Which part of the TMJ disc is innervated
the part between the posterior band and the bilaminar zone
the bilaminar zone also has a blood supply
Where is the masseter muscle located
anterior to the parotid gland
How many heads does the masseter have
2
superficial and deep
What is the origin of the masseter
zygomatic arch
Where in the zygomatic arch do the superficial and deep head originate
superficial –> zygomatic process + anterior zygomatic arch
deep –> posterior zygomatic arch + medial surface
Where does the masseter’s superficial head insert
lateral surface of angle of mandible
Where does the masseter’s deep head insert
ramus, superior to angle of the mnadible
What is the action of the masseter
elevating the mandible
Describe the temporalis
- Broad, fan shaped muscle
- Fills the temporal fossa
- Superior to the zygomatic arch
Where does the temporalis originate
temporal fossa
Where does the temporalis insert
Onto the medial surface, apex and anterior border of the coronoid process of the mandible
What is the action of the temporalis if entire muscle contracts
elevates mandible
What is the action of the temporalis if only the posterior part of the temporalis contracts
retraction of the mandible
How many heads does the medial pterygoid have
2
deep and superficial
What is the origin of the deep head of MP
originates from the pterygoid fossa on the mesial surface of the lateral pterygoid plate of the sphenoid bone
Where does the small superficial head of the MP originate
lateral surfaces of the pyramidal process of the palatine bone and maxillary tuberosity of the maxilla
Where does the MP insert
Both heads then pass inferiorly, posteriorly and laterally to insert on the medial surface of the ramus/angle of the mandible
What is the action of the MP
Muscle elevates the mandible
Parallels the masseter but weaker
Describe the laterla pterygoid
- Short, thick, conical muscle
How many heads does the LP have
2
superior + inferior
Where does the superior head of LP originate
originates from the infratemporal surface and infratemporal crest of the greater wing of the sphenoid bone
Where does the inferior head of LP originate
from the lateral surface of the lateral pterygoid plate of the sphenoid bone
Where does the superior head of LP insert
into the neck of the mandible at the pterygoid fovea
Where does the inferior head of LP insert into
into the anterior margin of the TMJ disc + capsule
What is the action of LP
o Assists in depressing the mandible by its inferior head
o Main action when both muscles contract is to bring the lower jaw forward thus causing the protrusion of the mandible
o If only one muscle is contracted, the lower jaw shifts to the contralateral side causing lateral deviation
What are the accessory muscles of mastication
suprahyoid
Name the suprahyoid muscles
- digastric
- mylohyoid
- geniohyoid
- stylohyoid
Name the infrahyoid muscles
- thyrhyoid
- sternohyoid
- omohyoid
- sternothyroid
What is A
Mandibular fossa
aka glenoid fossa
What is B
articular disc
What is C
mandibular condyle
What is D
articular tubercle
aka articular eminence
What are the 2 movements of the TMJ
rotation + translation
What is rotation also known as
hinge movement
How mouth mouth opening does the rotation allow for
up to 20mm
Where are the condyle and the disc during hinge movement
they remain within the articular fossa
What is the terminal hinge axis
it is the imaginary line the condylar head rotates around during rotational movement of the TMJ
What happens in translation
- LP contracts
- articular disc + condyle begin to move
- they travel downwards and forward along the incline of the articular eminence
- if they travel laterally then this results in lateral translation
- it produces maximum opening of the mouht
What are the causes of TMD
myofascial pain
disc displacement
degenerative disease
chronic recurrent dislocation
ankylosis
hyperplasia
neoplasia
infection
What is disc displacement
- disc slips out of place
What is anterior displacement
If the disc slips anteriorly
What is anterior displacement with reduction
disc slips forward but is able to go back to it’s correct place
What is anterior displacement without reduction
when the disc slips forward but is unable to go back to its correct place
What are the two types of degenerative disease
o Localised (osteoarthritis)
o Generalized/systemic (rheumatoid arthritis)
What is chronic recurrent dislocation
o Joint regularly dislocates where it slips out of the articular eminence and ends up infront of the eminence and stuck there
What is hyperplasia
o One condyle grows more than the other
What are examples of neoplasia that cause TMD
o Osteochondroma, osteoma or sarcoma
Describe the pathogenesis of myofascial pain
o Inflammation of the muscles of mastication or TMJ secondary to parafunctional habits
o Trauma either directly to joint or indirectly e.g sustained mouth opening
o Stress (resulting in muscle tension)
o Psychogenic
o Occlusal abnormalities (no evidence to support this)
What does our assessment consist of
history
intra/extra oral exam
special investigations (sometimes)
When looking at pain history, what do we want to focus on
location, nature, duration, exacerbating/relieving factors, severity, frequency, time of occurrence
What do we look at in the extra oral exam
MoM
joints
jaw movement
facial asymmetry
What are we looking at when we look at the joints
clicks and crepitus
What does crepitus point at
degenerative change
Intra-orally what do we look at
interincisal mouth opening
signs of parafunctional habit
What are signs of parafunctional habit
- cheek biting
- linea alba
- tongue scalloping
- occlusal NCTSL
When may we look at doing x-rays
when pathology suspected
severe trismus
What is normal mouth opening
42-55mm
What is the gold standard view for TMJ
MRI
What other views can be taken for TMJD
OPT
CT/CBCT
MRI
Transcranial view (TMJ view)
Nuclear imaging (tech-99)
Arthrography
Ultrasound
What are the common clinical features of TMJD
o Females > males
o Age: most common between 18-30 YO
o Intermittent pain of several months or years duration
o Muscle/joint/ear pain, particularly on wakening (likely clenching during the night)
o Trismus/locking (due to displacement where unable to reduce)
o Clicking/popping joint noises
o Headaches
o Crepitus indicates late degenerative changes
What are the differential diagnoses pain in TMJ area
- dental pain (wisdom teeth)
- sinusitis
- ear pathology
- salivary gland pathology
- referred neck pain
- headache
- atypical facial pain
- trigeminal neuralgia
- angina
- condylar fracture
- temporal arteritis
What are reversible tx for TMJD
px education
medications
reassurance
physical therapy
splints
What does px education consist of
Counselling
Electromyographic recording
Jaw exercises (physiotherapy)
What do the medications consist of
NSAIDS
Muscle relaxants
Tricyclic antidepressants
Botox (to paralyse masseter to reduce clenching)
Steroids
What does reassurance consist of
Soft diet
Masticate bilaterally
No wide opening
No chewing gum
Don’t incise foods
Cut foods into small pieces
Stop parafunctional habits e.g nail biting, grinding
Support mouth on opening e.g yawning
What does physical therapy consist of
Physiotherapy
Massage/heat
Acupuncture
Relaxation
Ultrasound therapy
TENS
Hypnotherapy
What are the splints in TMJD aka
bite raising appliance
What are the types of bite raising appliances
Anterior repositioning splint
Wenvac splint
Michigan splint
Lucia jig
What is the mechanism of bite raising appliances
o Exact mechanism unknown
o Theoretically, BRA stabilize the occlusion and improve the function of the masticatory muscles, thereby decreasing abnormal activity
o They also protect the teeth incase of tooth grinding
o Patients may need to wear the splint for several weeks before a benefit is felt
o The splint should be worn at the time of parafunction
What are the irreversible tx of TMJD
occlusal adjustment
surgery
What are the different types of TMJ surgery
Arthocentesis
Arthroscopy
Disc-repositioning surgery
Disc repair/removal
High condylar shave
Total joint replacement
What is disc displacement aka
internal derangement
What is joint clicking due to
lack of coordinated movement between the condylar and the articular disc
What happens normally in terms of coordination between the condyle and articular rdisc
compared to clicking
when the condyle moves forward around the eminence (when mouth is opened) the disc should move with it
What happens when there is clicking (displacement)
Because of increased pressure inside the joint, the disc slips in front of the joint while the mouth is closed and so they find translation difficult because the disc is trapped in front of the joint and they have to manipulate the joint to slip the disc back in place and at this point they may hear the click
The condyle has to overcome the mechanical obstruction before full joint movement can be achieved
Clicks may occur on opening or closing and can be classified as early, middle or late
What is the most common cause of clicking
anterior disc displacement with reduction
What happens in anterior disc displacement with reduction
o Disc is initially displaced anteriorly by the condyle during opening until the disc reduction occurs
What are the signs and symptoms of disc displacement
Jaw tightness/locking
Jaw movement is impaired for a short period of time until the disc reduces
The mandible may initially deviate to the affected side before returning to the midline
If anterior disc displacement + reduction is left untreated what can happen
may eventually progress to osteoarthritis
What is tx of anterior disc displacement + reduction
Counselling
Limited mouth opening to avoid stretching disc
Bite raising appliance
Occasionally surgery
If painless however, no tx required
How does trismus from trauma occur
Can occur after even minor traumatic events, will usually resolve spontaneously
If no resolution after acute phase, may require physiotherapy, therabite, jaw screw
