TMJ Flashcards
Size of the problem
- Percentage of population with signs – 50-75%
- Percentage of population with symptoms – 20—25%
- Percentage of population who seek treatment – 3-4%
- Women more likely to seek treatment
TMJ anatomy - condyle
Condyle
Condyle sits in fossa. Fibrous articular capsule envelopes joint which is reinforced by temporomandibular ligament
Inside the capsule is an articular biconcave disc. Disc divides joint into upper and lower compartments.
Arc of movement
Normal space between maxillary and mandibular incisors is 35-50mm. First half of opening is mainly hinging (rotation of condyle in the fossa).
Second half of opening mainly forward translation of condyle along eminence. Can see this if place own fingers over TMJ whilst opening mouth – first half, movement is imperceptible, second half can feel gliding movement.
TMJ - opening
Opening – a combination of muscle action facilitates this rotation and translation.
Geniohyoid – attaches from chin to hyoid, pulls chin down
Digastric – attaches from chin, to hyoid, back up mastoid process. Pulls chin down and backwards
Lateral pterygoid – forward translation of condyles and discs
TMJ - closing
Closing
Temporalis (posterior fibres) – backward translation of condyles
Temporalis (middle and anterior fibres), masseter and medial pterygoid elevate the mandible
Anterior part of temporalis and masseter is frequently painful on palpation, common source of symptoms.
TMJ - protrusion and retrusion
Protrusion – 10mm
Symmetrical forward translation of both condyles
Both lateral pterygoids pull condyles (and discs) forward
Retrusion
The return to rest position from the protrusion position
Both temporalis muscles (posterior fibres) pull condyles back
TMJ - lateral excursion
Lateral excursion – 10mm
The condyle on the opposite side is pulled forward
Condyle on the same side performs minimal rotation around vertical axis
Contraction of the lateral pterygoid muscles on opposite side
Combined with temporalis muscle on same side contracting to hold rest position of the condyle
Define TMD
Temporomandibular disorder (TMD) has been defined as:
• A collective term embracing a number of clinical problems that involve:
o The masticatory muscles
o The temporomandibular joint and associated structures
o Or both
Classification of common musculoskeletal TMDs (3):
Masticatory muscle disorders
Temporomandibular joint disorders
Headache
Masticatory muscle disorders:
Myalgia:
1. Local myalgia
2. Myofascial pain
3. Myofascial pain with referral
Mainly involves large closing muscles – temporalis and masseter.
Signs and symptoms:
• Familiar pain in the muscles on jaw function/parafunction, palpation and movement tests
Myofascial pain with referral:
Report of pain at a site beyond boundary of muscle being palpated
E.g. masseter – pt may report toothache, headache and earache
Awareness of referral patterns will help with differential diagnosis
Headache
Headache attributed to TMD:
Involves temporalis muscle
Signs and symptoms:
Familiar headache in temporal area on function, palpation of temporalis and movement tests
TMJ disorders (4):
Arthralgia
Disc disorders
Degenerative joint disease
Subluxation
Disc disorders (4):
- Disc displacement with reduction (DD+R)
- Disc displacement with reduction with intermittent locking (DD+R)
- Disc displacement without reduction with limited opening (DD-R)
- Disc displacement without reduction without limited opening (DD-R)
Disc displacement with reduction
Common
The disc is no longer maintained on the condyle throughout the range of motion.
Normally disc is positioned on condyle. In DD+R, the disc is displaced anteriorly.
On opening – the disc reduces, or returns back to the condyle.
At mid-range, disc reduces with a ‘click’.
On closing, disc is anteriorly displaced again, sometimes with a click.
Sometimes may find ipsilateral deviation with opening (which corrects)
Disc displacement with reduction with intermittent locking
DD + R + IL
Same as DD + R but with added:
May get intermittent TMJ locking/sticking. A manoeuvre may be required to open mouth.