TMJ Flashcards
(37 cards)
describe the articular disc
Fibrocartilaginous
Plays a primary role in stability of the TMJ
Middle portion of the disc is avascular and aneural
Anterior and posterior parts are innervated
Medial and lateral components of the disc are stabilized by collateral ligaments
what purpose does the posterior ligament serve
Posterior ligaments (bilaminar zone) Limits severe opening Nutritional function of the joint The fibrous joint capsule Superior stratum attaches to the posterior mandibular fossa Allows disc to translate forward
Bilaminar Zone
Intercapsular mass of soft tissue between the superior and inferior strata Very vascular Well supplied with nerve endings Supplies the condyle as well as the ear Tinnitus Note: proximity of eat to TMJ
what part of the TMJ joint is the weakest??
Anterior structures
Weakest part of the joint
Anterior fibrous capsule connects to the anterior portion of the disc
Superior head of the lateral pterygoid attaches anterior and medially on the disc
what is the main ligament responsible for the suspension of the mandible
Lateral aspect
Temporomandibular ligament
Main ligament responsible for suspension of the mandible
Restricts backward and lateral movements
Guides the arthrokinematic motion of the joint
Can be strained with excessive downward motion, such as from a occlusal fulcrum from a molar
Ex: mouth up for 40 min at the dentist…cap put on and now it makes a fulcrum
what strains the LCL what motion
Lateral Fibrous capsule Lateral collateral ligament Stabilizes the disc Medial displacement of the disc will strain the LCL
Medial ligament is taught during what motion
Sphenomandibular ligament
Suspends the manible and is taut in terminal opening
what ligament prevents extreme opening of the mouth??
Medial
Stylomandibular ligament
Limits extreme opening—the stopper
The MCL stabilize the disc on top of the condyle
Medial displacement of the condyle with lateral disc displacement, as seen with crossbite, can strain these ligaments
the synovials probably not that important
Highly vascular and well innervated connective tissue that lines the upper and lower joint compartments of the TMJ
Produces synovial fluid
Important proprioceptive roles
What does the temporalsis due and is ti responsible for headaches
Temporalis
Origin: Temporal fossa
Insertion: Coronoid process and ant. border of ramus
Function: Bilateral=elevation; unilateral=deviates mandible to same side; retract mandible, and guides biting motion
Potential for headaches or cranio fascial pain
what actions does the masseter do??
Masseter (con’t)
Function: Initiates elevation of the mandible and adds force to closure
Contributes to clenching and grinding
what does the lateral pterygoid muscle do??
Lateral pteryoid
Function: Mandibular depression as it pulls the condyle and disc forward (inferior head)
Stabilizes the condylar head and disc against the articular eminence during closing (superior head)
Both heads perform side to side movement, such as grinding
what does the medial ptyergoid do??
Function: elevates mandible, limits protrusion when mandible is depressed, deviates mandible to one side unilaterally, and participates in chewing motion
what does the diagastric muscle do??
Function: If the hyoid is fixed, it pulls the mandible back and down and functions during retrusive and opening movements
what is the 4;1;1 realtionship about and what 3 planes does the mandible move in??
3-planes of movement Opening Lateral excursion Protrusion There is a 4:1:1 relationship For every 4mm of opening, we should have 1mm of lateral excursion and 1mm of protrusion
Biomechanics what does the articular disc help with in the TMJ.
The articular disc
The 2 bony surfaces of this joint are both convex, leading to an unstable joint. A biconcave articular disc in the TMJ provides both stability and prevents wear of the articular cartilage
how much is normal opening of the mouth?? and what degree does rotation usually occur??
Arthrokinematics
Normal opening is 35-40mm
First 12mm is primarily a rotation
Condyle moves anteriorly and disc moves posteriorly relative to each other
As the temporomandibular lig. gets taut, disc and condyle move as one by means of translation
Terminal opening: condyle translates forward and downward on the eminenc
what is the tounges primary role??? and how many times do we swallow a minute when not eating or drinking
Tongue
Primary role is swallowing
During normal swallowing, the teeth are in occlusion, the tongue slightly in front of the resting position with the muscles of mastication contracting strongly.
We typically swallow 1 time per minute when not eating or drinking
how does a forward head affect the path of opening
Forward head posture:
Affects path of opening and closing
Affects the amount of muscle work involved
Affects ROM of both the TMJ and C-spine
Ex: Mean amount of opening increases by 8.3mm when comparing a forward head from a retracted head posture
Same holds true for shoulder ROM with T-spine
what else does the forward head posture do!!
Forward head posture results with an increased distance between the chin and sternum, stretching the hyoid muscles
This results in pulling the mandible back and down
This increases activity of the masticatory muscles and cranial extensors
Possible cause of pain
Pathological causes of pain
Degenerative changes-loss of fibrocartilage
Inflammation
possible ligamentous can cause problems to the disc!!!
Ligamentous lesion Overstretch Continuous strain LCL strain MCL strain Posterior ligament strain Retrodiscitis-repetitive trauma to the insertion of the posterior ligament on the disc Temporomandibular ligament strain
desribe the capsular pattern of the jaw.
Capsular pattern
Consists of vertical capsular retraction, prevents distraction (downward movement) of the condyle
Constriction of the capsule can result in loss of condylar-vertical height due to a displaced disc, which as a result causes a posterior and superior displacement of the condyle
what are somethings that could cause muscle tendon pain
Masseter: clenching in maximum occlusion with parafunction
Posterior temporal tendinitis: hypermobility resulting in excessive anterior translation of the condyle, impinging on the tendon, sustained excessive opening of the mouth
Suboccipital/shoulder girdle pain: due to craniomandibular parafunction; decreased craniocervical angle
