TMJ Flashcards
What are 5 causes of TMJ dysfunction?
- Macrotrauma (e.g. whiplash, direct blow, iatrogenic dental procedures)
- Microtrauma from parafunctional clenching and bruxing
- Degenerative OA
- Systemic conditions
- Mental health disorders
What population is at highest risk for TJM dysfunction?
Women around reproductive age
TMJ is what type of joint?
Bilateral diarthrodial (synovial) joint
TMJ articular surfaces and the disk are covered in what?
Fibrocartilage that has superior reparative potential and resistance to wear/tear
During mouth opening what movement occurs?
Superior cavity: translation
Inferior cavity: rotation of the condyle
What is the shape of the disk in the TMJ?
Biconcave (“bow-tie”)
What parts of the TMJ articular disks have innervation/vascularization?
Anterior & posterior
What is the function of the temporomandibular ligament aka “lateral” ligament?
Limits rotation of the condyle and posterior displacement
What is the function of the collateral ligaments?
Restrict excessive medial/lateral movement of the disk
What are the 2 accessory ligaments of the TMJ?
Stylomandibular and sphenomandibular ligaments
What is the function of the accessory ligaments in the TMJ?
Restrict excessive protrusion
What are the muscles of mastication?
- Masseter
- Temporalis
- Lateral pterygoid
- Medial pterygoid
What is the action of the masseter muscle? (both unilat & bilat contraction)
Unilat: slight ipsilat excursion
Bilat: superficial = protrusion, deep = retraction
What is the insertion of the temporalis muscle?
Coronoid process and medial border of the mandibular ramus
What is the action of the temporalis muscle? (both unilat & bilat contraction)
Unilat: ipsilat lat excursion
Bilat: elevation/retraction of mandible
What is the function of the medial pterygoid?
Unilat: contralat excursion
Bilat: elevation/protrusion
What is the function of the lateral pterygoid?
Unilat: contralat excursion
Bilat: protrusion
What are the suprahyoid muscles (4)?
anterior/posterior belly of the digastric, mylohyoid, geniohyoid, and stylohyoid
What are the infrahyoid muscles (4)?
sternohyoid, sternothyroid, thyrohyoid, and omohyoid
Muscles involved in TMJ elevation (closing)
Masseter, temporalis, medial pterygoid, lateral pterygoid (SUPERIOR)
Muscles involved in TMJ depression (opening)
Lateral pterygoid (INFERIOR), suprahyoids, infrahyoids
Muscles involved in TMJ protrusion
Massater (SUPERFICIAL), lateral pterygoid, medial pterygoid
Muscles involved in TMJ retrusion
Massater (DEEP), temporalis, suprahyoids
Muscles involved in TMJ lateral excursion
IPSILAT: masseter, temporalis
CONTRALAT: medial/lateral pterygoids