Temporomandibular Joint Dysfunction Flashcards
TMJ dysfunction and Revision of anatomy of TMJ
What are some nomenclature for temporomandibular dysfunction?
- Myofascial pain dysfunction
- Pain dysfunction syndrome
- Facial arthromyalgia
- Costen’s syndrome
- TMJ
What are the suprahyoid muscles? (Accessory muscles of mastication)
- Digastric
- Mylohyoid
- Geniohyoid
- Stylohyoid
Name the infrahyoid muscles (Accessory muscles of mastication)
- Thyrohyoid
- Sternohyoid
- Omohyoid
- Sternothyroid
What is the origin and insertion of the masseter muscle? What is its action? What is its innervation? What is its blood supply
- Origin has two places on Zygomatic arch
Superficial origin : maxillary process of zygomatic bone, inferior border or zygomatic arch (anterior 2/3rd)
Deep origin : deep/inferior surface of zygomatic arch (posterior1/3rd) - Insertion onto lateral surface of ramus and angle of mandible
Function : Elevates and protrude mandible
Innervation : masseteric nerve of mandibular nerve CN V3
Blood supply : Masseteric artery
What is the origin and insertion of temporalis muscle? What is its action? What is its innervation? What is its blood supply
Originates : from temporal fossa and deep part of temporal fascia
Insertion : Apex and medial surface of coronoid process of mandible
Function : Anterior fibres elevate mandible
Posterior part retracts mandible
Innervation : Deep temporal branches of mandibular nerve CN V3
Blood supply : Deep temporal branches of maxillary artery, middle temporal branches from superficial temporal artery
What is the origin and insertion of medial pterygoid muscle? What is its action? What is its innervation? What is its blood supply
Superficial origin : tuberosity of maxilla, pyramidal process of palatine bone
Deep origin : Medial surface of lateral pterygoid plate of sphenoid bone
Insertion : Medial surface of ramus and angle of mandible
Function : Bilateral contraction elevates and protrudes mandible
Unilateral contraction medial movements (rotation) of mandible
Innervation : Medial pterygoid nerve of mandibular nerve CN V3
Blood Supply : Pterygoid branches (max artery, buccal artery, facial artery)
What is the origin and insertion of lateral pterygoid muscle? What is its action? What is its innervation? What is its blood supply
Superior head origin : infratemporal crest of greater wing of sphenoid bone
Inferior head origin : Lateral surface of lateral pterygoid plate of sphenoid bone
Superior head insertion : Joint capsule of TMJ
Inferior head insertion : Pterygoid fovea on neck of condyloid process of mandible
Function : Bilateral contraction protrudes and depresses mandible whilst stabilises condylar head during closure
Unilateral contraction medial movement of mandible
Innervation : Lateral pterygoid nerve of mandibular nerve CN V3
Blood supply : Pterygoid branches of maxillary artery, ascending palatine branch of facial artery
What parts of the articular disc is innervated and can feel pain from?
- Only the bilaminar zone is innervated
- Articular tissues and dense part of articular disc no nerve supply
- Feel pain when bilaminar zone is compressed by condylar head or stretched when disc is moved
Label this diagram of the right hand side mandible
Label this internal view of mandible
What branches does the mandibular nerve split into?
- Buccal nerve (Anterior division)
- Auriculotemporal nerve (post_
- Inferior alveolar nerve (post)
- Lingual nerve (post)
What does the inferior alveolar nerve divide into?
- Nerve to mylohyoid (before entering mandibular foramen)
- Incisive nerve
- Mental nerve
- Inferior dental plexus
Label this diagram
What type of joint is the temporomandibular joint? What is the TMJ?
- Hinge type synovial joint that connects the mandible to the rest of the skull
- It is an articulation between the mandibular fossa and the articular tubercle (eminence) of the temporal bone, and the condylar process of the mandible
Why is the TMJ classed as atypical?
- Classed as synovial type joint but it is atypical in that its articular surfaces lined by fibrocartilage rather than hyaline cartilage
What is the main function of TMJ? What movements can the joint do?
- To facilitate movements of the lower jaw
- Allows range of movement of lower jaw, namely translational movements (protrusion / retraction and lateral deviation) and rotational movements (elevation and depression)
What are the main bones involved in formation of TMJ and what do they form?
- Inferior part of joint formed by condylar head of mandible
- Superior part of joint formed by mandibular fossa and articular tubercle on the Temporal bone
Called articular surfaces
What structure lies between the two articular surfaces of the TMJ? What is it’s function?
- Articular disc of TMJ
- Separated the articular surfaces
- Disc stabilised condyle of mandible within join , reduces frictional force between articular surfaces and may aid lubrication of joint
How Does movement occur in the TMJ?
Superior compartment allows translation movements
- protrusion
- Retraction
- Left and right lateral deviation
Inferior compartment allows rotational movement
- Depression
- Elevation
- Both rotation and translation occur simultaneously therefore allow complex movements that allow people to chew and talk
What is the blood supply of the TMJ?
- Deep auricular artery (form maxillary artery)
- Superficial temporal artery (terminal branch of external carotid artery)
- Anterior tympanic artery (branch of maxillary artery)
What is the venous drainage of TMJ?
- Superficial temporal vein and maxillary vein
What is the innervation of TMJ?
- Auriculotemporal branch
- Masseteric
- Deep temporal branch
All branches of mandibular division of trigeminal nerve CN V3
What are some more common causes of TMD?
Myofascial pain
Disc displacement
- Anterior with reduction
- Anterior without reduction
Degenerative disease
- Localised like osteoarthritis
- Generalised (systemic) like RA
What is meant by anterior disc displacement with reduction?
- Articular disc displaces anteriorly to condylar head and when the mouth is opened the disc relocates on the condylar head
What is meant by anterior disc displacement without reduction?
- Articular disc displaces anteriorly to condylar head and does not move back to orig position (can get stuck by articular tubercle )
- Acts as barrier to condylar movement limiting mouth opening
What are some other less common causes of TMD?
- Chronic recurrent dislocation
- Ankylosis
- Condylar Hyperplasia
- Neoplasia (osteochondroma, osteoma or sarcoma)
- Infection
If this a pt first time with dislocation. What can you do to reposition the jaw?
- Place fingers on buccal sulcus either side of teeth and support body and angle of mandible
- Push down and back slowly to allow jaw closure
- Muscle relaxants like diazepam can also be given
What is condylar hyperplasia?
- One condylar head of mandible grows more than the other
- Leading to squint jaw (facial asymmetry)
- requires surgery to treat
What is the pathogenesis of Myofascial pain?
- Inflammation of MOM or TMJ secondary to parafunctional habits
- Trauma , either directly to joint or indirect via sustained opening during dental txt
- Stress due to muscle tensing up
- Psychogenic (clenching)
- Occlusal abnormalities (no evid to support this)
Social history is important in pts with suspected TMJ pain. What is included within this?
- occupation
- Stress
- Home circumstances
- Sleeping pattern
- recent bereavement
- Relationships
- Habits
- Hobbies
Extra orally what are we assessing (focusing on TMJ)
- MOM
- Joints - clicks early or late / crepitus
- jaw movements
- Facial asymm
Intra orally what are we assessing (focus on TMJ)
- Interincisal mouth opening (use willis bite gauge)
- Signs of parafunctional habit inc
- Cheek biting
- Linea alba
- Tongue scalloping
- Occlusal non carious tooth surface loss
- MOM
What special investigations would you do if any?
- Not usually required but if suspicious of pathology then
- OPT
- CT/CBCT
- MRI
- Transcranial view (TMJ view)
- Nuclear imaging
- Arthrography
- Ultrasound
What is the aetiology of TMD?
- Females > males
- Most common 18-30yrs
What are the common clinical features of TMD?
- Intermittent pain of several months or years duration
- Muscle / joint / ear pain partic on wakening
- Trismus / locking
- Clicking / popping joint noises
- Headaches
- Crepitus (crunchy sound) indicates late degenerative changes
What are the differential diagnosis for TMD pain?
- Odontogenic pain
- Sinusitis
- Ear pathology
- Salivary gland pathology
- Referred neck pain
- Headache
- Atypical facial pain
- Angina (referred)
- Condylar fracture
- Temporal arteritis (serious and can lead to blindness)
What is the txt of TMD?
- Pt education
- Counselling
- Jaw exercise
- Soft diet
Med
- NSAIDs
- Muscle relaxants
- Tricyclic antidepressant
- Botox (paralyses muscle)
- Steroids injection in joint reduce inflammation
What is involved in Counselling of TMD?
Reassurance
Soft diet
Masticate bilaterally
No wide opening
No chewing gum
Don’t incise foods
Cut food into small pieces
Stop parafunctional habits e.g. nail biting, grinding
Support mouth on opening e.g. yawning
What reversible txt is available for TMD?
Physical therapy
- Physiotherapy
- Massage/heat
- Acupuncture
- Relaxation technique
- Ultrasound therapy
- TENS (Transcutaneous
- Electronic Nerve Stimulation)
- Hypnotherapy
Splints
- Bite raising appliances
- Anterior repositioning splint
What bite raising appliances are available?
- Thermoplastic retainer (not really as not thick enough)
- Wenvac splint
- Anterior repositioning splint
- Hard acrylic for lower
Need to cover all biting surfaces of one arch - never use sectional
What is the theoretical bite raising appliance mechanism?
- Stabilise occlusion and improve function of masticatory muscle thereby decreasing abnormal activity
What irreversible txt is available for TMD?
- Rarely done
- TMJ surgery inc
Arthrocentesis
Arthroscopy
Disc-repositioning surgery
Disc repair/removal
High condylar shave
Total joint replacement
Why might a joint click? What is it called?
- Termed anterior disc displacement with reduction (internal derangement)
- Due to lack of coordinated movement between condyle and articular disc
- Condyle has to overcome mechanical obstruction before full joint movement
- Clicks may occur on opening or closing by disc suddenly slip back
Signs and symptoms of articular disc displacement with reduction. What may it progress to?
- jaw tightness/locking i.e. 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 left untreated may progress to osteoarthritis
What is the txt of disc displacement with reduction/
Counselling
Limit mouth opening
Bite raising appliance
Surgery occasionally may be required
If painless no txt required and reassure
A pt presents with Trismus form trauma. What will have happened to the muscles for this to occur?
- usually due to haematoma formed in lateral pterygoid muscles leading to muscle spasm - lim mouth opening
How can minor trauamtic trismus occur?
- IDB
- Prolonged dental txt
- Infection
If no resolution of trismus after acute phase what can be done txt wise?
- Physiotherapy
- Therabite jaw motion rehab
- Jaw screw
When is it deemed Chronic TMD?
- Pain lasting more than 3 months
When should you refer to oral med or oral and maxfac?
- History of trauma or fracture to TMJ
- Markedly lim mouth open (closed lock)
- Pain or red jaw function in ots with known rheumatic joint disease
- Recurrent dislocation of TMJ
- Pers worsening of symptoms lasting more than 3 months
- Pers inability to manage normal diet
- Severe pain and dysfunction from internal derangement that does not respond to conservative measures
- Uncertain diagnosis
What is the average interincisal distance?
- Approx 14mm
