Musculoskeletal approach to the Jaw
Joint
Muscles
- Primary muscles
- Masseter
- Temporalis Branch
- Medial pterygoid
- Lateral pterygoid
- Secondary muscles
- Suprahyoid group: Digastric, Geniohyoid, Mylohyoid, Stylohyoid
- Infrahyoid group: Omohyoid, Sternohyoid, sternothyroid, thyrohyoid
Muscle and Joint interaction
The muscle of mastication are divided by size and force potential into two groups: primary and secondary
In addition, mechanoreceptors and sensory nerves from oral mucosa, periodontal ligaments, and muscles provide the nervous system with a rich source of proprioception. This sensory information helps protect the soft oral tissues, such as the tongue and cheeks, from trauma caused by the teeth during chewing or speaking. Furthermore, the sensation helps coordinate the neuromuscular reflexes that synchronize the functional interaction among the muscles of the TMJ and in the craniocervical region. The sensory innervation from the TMJ is carried through two branches of the mandibular nerve: auriculotemporal and masseteric
Tests and Measures
Patient reported outcome measures for TMD:
- Jaw functional limitation scale - 20
- https://muscleandspinerehab.com/wp-content/uploads/2019/05/TMJ-Jaw-Functional-Limitation-Scale.pdf
- Sample Questions:
- Scale 0-10, rate your difficulty in:
- Chewing tough foods
- Making certain facial expressions
- Talk and sing
Evaluation
Subjective that might differ a TMJ case from a c/s case:
- ADLS (eating, brushing)
- Surgery healing risk factors (obesity, etc)
- Why they had the replacement
- Do they grind?
- When is the click?
- Sleep
Key objectives:
- Therabite ROM
- When the clicking occurs
- Lateral pterygoid palpate
- Palpate other muscles
- Assessing opening and closing kinematics
Assess surrounding structures
- Upper cervical ROM / Postural contributions
- Suboccipital tightness could occur
- Pts w/ TMD have 70% chance of having C/S limitations
- Upper cervical – OAJ mobility
- Cervical ROM and upper quad function
Motor patterns
- Jaw opening/closing patterns and mobility
TMJ
functional/PROM
- Palpation and auscultation of the joint
- Intraoral exam
- Signs of bruxism
- Scalloping
Palpation
Muscle palpation: Region is usually sensitive, but increased TTP on the involved side is almost always reported by patients with TMD
Bite assessment
- Bite Assessment
- Cotton roll test
- Alignment
Postural assessment
- Increased tension on infrahyoids.
- Depresses & retrudes mandible via suprahyoids.
- Posteriorly displaced condyle.
- Compression of retrodiscal tissues.
- Lateral pterygoid protrudes to prevent compression.
- Anterior displacement of articular disc
Posture stretches infrahyoid muscles, pulling on hyoid, pulling on suprahyoids, mandible drepssed and retrudes. Omohyoid is attached to scapula, depressed, downwardly rotated, or protracted scapula can place additional stretch on this muscle🡪 pull mandible.
Imaging
Can have advanced imaging
- US → 33% false positive rates
Functional Activities
Also ask about functional activity Speech, lip biting/nail biking, mouth breathing, tongue/jaw thrust
Disc Assessment
ADDwR or ADDwoR - ant disc displacement w reduction or without
Ear symptoms
- Aural Fullness (clogged ear sensation) (74.8%) – ear clog
- Secondary Otalgia (55%)
- Tinnitus (52%)
- Vertigo (40%)
- Hearing loss (38%)
Pathologies and Pathokinematics
Pathokinematics and mvmt classifications: Opening: click during opening , click during close, – disc ant to begin with not even in place (sound of disc snappinginto place on top of condyle, then it snaps back out during closing ) ADD w R (ant disc displacement w reduction) Ant displaced disc: loose/stretched retrodiscal laminae or tight sup lat pterygoid Likely hypermobile opening (not limited opening)
Opening – no click – ADDwoR → ant disc displacement without reduction Disc in front of condyle when opening, so blocks condyle from sliding further forward Limited opening Starts out limited, as condition progresses, it normalizes (disc just stays out and goes further in front) Harder to treat if pain is associated with it Retrodiscal laminae super stretched out (so we have to manually shove the disc back ) Kenny says we can :Pull jaw far open (gap it) to try to let the disc slide back, then tell them to not open their mouth as much after so that healing occurs and disc stays. (hard tho he says) Open lock PDD posterior disc displacement Limits ability to close mouth Open, condyle slides forward, disc is stuck behind, so as you close, disc is jammed in there, so you cant close all the way Open locked
DDX
True TMD:
- Joint/Capsule
- Articular Disc
- Fracture
- TMJ Hyper/hypomobility (dislocation or subluxation of condyle)
- FHP = leads to hypermobility
Contributing to TMD symptoms:
- HA and posture
- Nerve and inner ear dysfunction (trigeminal neuralgia)
- Stress/clenching/bruxism/myofasical pain
- Meniere’s Disease
Hypomobility
C-curve when opening and closing mouth
Muscular weakness
S-curve when opening and closing
Interventions
- Joint mobility
- move normally and dont go to the point of aberrations
- Cue
- Placing tongue on roof of mouth: Limits ROM and helps prevent excessive ROM
- Rocabado:
- Tongue on roof of mouth +6 deep breaths
- Tongue on roof - open and close 6x
- Tongue on roof - resisted opening and lateral excursion (2 fingers)
- C/s flexion + chin nod (OA flx)
- C/S retraction
- Scap and t/s posture - retraction + neutral spine
Rehabilitation
Best starting plan regardless of the patient: Decrease stress and treat posture
- Pt education
- Relaxation, postural correction , body mechanics
- Oral habits – should you chew food on one side? → debatable, some ppl think that if u chew on hurt side it gaps it, but he says know chew on side that hurts less. If no pain differs→ split food on both sides
- Consider aid of modalities
Awareness and mindfulness of: ❏breathing, ❏posture,
❏precise and purposeful jaw movement Multiple times a day, small bouts to emphasize good posture and timely stretching! Don’t forget C/S isometrics and DNF activation!
Hypermobility
Tongue on roof of mouth - limits full opening, helps to stabilize and control for hypermobility and coordination