TMJ

TMJ

1. Functions:

   • Movement of Mandible
     • Mastication
     • Speech
     • Respirations

2. Type of joint

   • Ginglymoarthrodial
     • Hinge/rotational
     • Glides/slides

3. Innervations

   • Mandibular N (CNV-trigeminal , V3)
     • Auricoculotemporal/masseteric branches
   • Motor functions by muscles of mastication
   • Blood- Ext Carotid artery
   • Venous return: sup temporal, max, pteryogoid plexus of veins
   • Lymphs: Sup deep cervical nodes

4. Joints Bones

   • Temporal
     • Cranial bone
     • Articulates inferior aspect/squamos part
     • Postglenoid process
       • Articular eminence
         • Articular FOssa
   • Mandible
     • Facial Bone
     • Articulating surfaces of mand condyle
       • Strongly convex in anteroposterior
         • Slightly convex mediolaterally

5. Joint Capsule

   • Completely encloses TMJ
   • Attaches to marginal the articular surface of condyle

6. JOint DIsc/meniscus

   • Synovial cavities
     • Upper/lower
     • Synovial FLuid
   • Upper Division
     • Attached to temporal bone's glenoid process
   • Lower division
     • Neck of condyle
   • Avascular/Aneural
   • Aging/truama can cause perforation/displacement

7. Ligaments

   • Band of fibrous tissue connecting bones
   • Temporomandibular
     • Major
     • Provides strength
     • Located lateral side of each joint
     • Prevent excessive retraction
     • Base attached to zygo process; lateral to art. eminence
     • apex is fixed to lateral side of the neck of mandible
   • Stylomandibular
     • from styloid process to angle of mandible
     • Separates parotid/submand salivary glands
     • Taut when mandible is protruded
   • Sphenomandibular
     • Located on medial side of mandible
     • Not considered part of TMJ
     • IA Nerve descends between this and the mand ramus to gain access to mental F
       • OverLaps F b/c of attachment to lingula
     • Outer barrier to diffusion LCA if medial mandible os not contacted with needle at deeper mand F w/ IA N

8. Jaw Movements

   • Gliding
     • Between disc/art eminence in upper synovial cavity
     • Protrusion/ forward
       • Bilateral contraction of lateral pterygoid muscles
     • Retraction/ Baclward
       • contraction of post parts of temporalis
         • supra hyoid
   • Hinge
     • Elevation/retraction/closing
       • Gliding in both upper SC/Rotation in both Lower SC
       • Masseter, temporalis, Medial pterygoid/bilateral contraction
     • Depression/protrusion/opening
       • Gliding in both upper SC/Rotation in both Lower SC
       • Suprahyoid /lateral pterygoid/bilateral contraction
   • Lateral Deviation/Shift contralateral
     • Gliding in 1 USC while condyle /disc of other side spin around an approx vertical axis w.in USC
       • Lateral Pterygoid w/ unilateral contraction

9. Freeway space in normal resting position is 2-4 mm between opposing arches

10. Palpation 1-2 cm anterior to trigs

11. Clinical Considerations

    • TMD
      • Palpation exam
      • MRI
    • Joint sounds occur due to disc dearrangment
      • Post part of disc gets caught in condyle head and art. eminence
    • TMD symptoms/sounds are found in 40-60% of people w/out TMD
    • Most cases improve overtime if habits are fixed
    • Subluxation/dislocation
      • Head of ea. condyle moves too far anteriorly on the art. eminence
        • Trismus
          • Reduced opening of jaw
          • can occur with odontogenic infections also
            • Shift mandible down and back w/ fingers and thumb of both hands equally on both sides