TMJ – NORMAL ANATOMY PPT

| July 8, 2013 | 0 Comments

TMJ – NORMAL ANATOMY PPT

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The Temporomandibular joint (TMJ) 

The Temporomandibular joint (TMJ) is composed of the temporal bone and the mandible, as well as a specialized dense fibrous structure, the articular disk, several ligaments, and numerous associated muscles.

 

Also called as craniomandibular joint / articulation.

ANATOMICALLY  :- 

                            TMJ is diarthrodial (  which is a discontinuous articulation of bones permitting freedom of movement )

 

It is also a synovial joint, lined on its inner aspect by a synovial membrane, which secretes synovial fluid. The fluid acts as a joint lubricant and supplies the metabolic and nutritional needs of the nonvascularized internal joint structures.

 

FUNCTIONALLY

                               The TMJ is a compound joint, composed of four articulating surfaces:

  the articular facets of the temporal bone and of the mandibular condyle and the superior and inferior surfaces of the articular disk.

TMJ CORONAL VIEW

 

Mandibular (glenoid) fossa

Limits :- anteriorly, the articular eminence      

                                  or tubercle

                posteriorly, a small conical post 

                                   glenoid tubercle

 

Articular eminence :- small prominence on the zygomatic arch. Strongly convex anteroposteriorly n somewhat concave mediolaterally.

 

Post glenoid tubercle :- separates fossa laterally  from tympanic plate n tympanic plate separates the TMJ from the bony part of the external auditory canal.

 

 

Glenoid fossa :- lined by a dense avascular fibrocartilage n in crosssection the fossa n eminence form a hazy ‘s’ posteroanteriorly.

 

 

Mandibular component

Mandibular condyle :- 

broad laterally n narrow medially.

Mediolaterally – bt. 13 to 25 mm

Anteroposteriorly – bt. 5.5 to 16 mm

N.T.-The articular part of condyle is covered by fibrocartilagenous tissue n not with hyaline cartilage, as in most joints of the human body

 

 

SOFT TISSUE ANATOMY

TMJ capsule

TMJ ligaments

Disc(meniscus)

Synovial membrane

 

 

CAPSULAR LIGAMENT (LATERAL VIEW)

 

It encompasses each joint, attaching superiorly to the temporal bone along the border of the mandibular fossa and eminence and inferiorly to the neck of the condyle along the edge of the articular facet.

 

 It surrounds the joint spaces and the disk, attaching anteriorly and posteriorly as well as medially and laterally, where it blends with the collateral ligaments.

 

 FUNCTION of the capsular ligament is to resist medial, lateral, and inferior forces, thereby holding the joint together. It offers resistance to movement of the joint only in the extreme range of motion.

 

 A secondary function of the capsular ligament is to contain the synovial fluid within the superior and inferior joint spaces

 

Synovial fluid

 

Synovial fluid is considered an ultrafiltrate of plasma. It contains a high concentration of hyaluronic acid, which is thought to be responsible for the fluid’s high viscosity.

The proteins found in synovial fluid are identical to plasma proteins.

Alkaline phosphatase, which may also be present in synovial fluid, is thought to be produced by chondrocytes. 

Leukocytes are also found in synovial fluid.

 Only a small amount of synovial fluid, usually less than 2 mL, is present within the healthy TMJ.

 

Functions of the synovial fluid include lubrication of the joint, phagocytosis of particulate debris, and nourishment of the articular cartilage.

Accessory ligaments

Sphenomandibular ligament :- it is a flate band arising from the spine of sphenoid & the petrotympanic fissure,runs downward n medially to the TMJ capsule n gets inserted on the lingula of the mandible.

 

Remnant of meckle’s cartilage.

 

N.T :- maxillary artery n auriculotemporal nerve lies bt. It n mandubular neck. 

 

The stylomandibular ligament :- it is dense thick band of deep cervical facia extending from the styloid process to the mandibular angle.  

 

Articular disc ( meniscus )

 

Composed of dense fibrous connective tissue and is nonvascularized and noninnervated.

Anatomically the disk can be divided into three general regions as viewed from the lateral perspective: 

The anterior band

   the central intermediate zone, and 

 

   the posterior band.

 

TMJ LATERAL VIEW

It promotes lubrication , energy absorption n joint range of motion.

It acts as shock absorber enabling the articulating bones to move against each other with minimum friction n heat production. 

 

Disc has very little potential for repair after insult. 

Blood supply-

                       Branches from Superficial  

                       temporal & Maxillary Artery

 

Nerve supply-

                              Auriculotemporal 

                            & Masseteric Nerve

 

 

TMJ PATHOLOGY ,  PATIENT’S HISTORY 

Age    –        Younger-MPDS common 

                      Older degenerative disease common

 

  Occupation –

                         Higher class people

 

 H/O pain –       MPDS – dull & morning time 

                          TMJ pain –  Sharp & increased

                                               during function

 

 Jaw & joints symptoms

 

Oral habit :              Bruxism

                                    Chewing pattern

 

 Medical history :        Rheumatoid arthritis

                                     Extraction

                                     Trauma   

  

  H/O     :                    Headache 

                                    Back pain 

                                    Ear ache

 

Family history  :         Rheumatoid arthritis 

                                    Osteoarthritis 

CLINICAL EXAMINATION

 

Facial symmetry

  Mouth opening

  TMJ palpation

  Muscle palpation

  Dental examination

 

 

 

DIAGNOSTIC STUDY

Plain radiography:

        Trans orbital view or antero-posterior view.

Trans cranial or lateral view.

Trans pharyngeal

Reverse towne’s

Cephalometric

Water’s view

Xeropadiography 

 

    Conventional tomography:

 

Orthopantamography

Linear tomography

Corrected tomography

 

Computed tomography;

Adv.  It provide superior osseous anatomical images 

         without any superimposition than conventional x-   

         ray.And in different plane.

e.g.     axial

          saggital

          coronal

                      It is good for hard tissue.

 

Disadv.  Can’t asses dynamic depiction of soft tissue

                       components.

    ( MRI )

         Adv.        –  Doesn’t use ionising radiation.

                   non invasive

                  excellent for soft tissue

 

Disadv.       – very expensive

                      patient discomfort

 

Arthrography:-

               Defect in position or structure of the joint disc & its attachment can be determined using arthrography.

            arthrography is performed by injecting the contrast madia in to the joint space and after it radiograph is taken.           

Arthroscopy

 

Electromyography

 

 

 

Category: Oral Anatomy

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