SEMINAR ON

TEMPORO-MANDIBULAR

JOINT ANATOMY

GUIDED BY – DR.NITIN JAGGI (PROF.& HOD) DR. ASHISH SINGH (PROF.) DR.NIKHIL PUROHIT(READER)  DR.RANJANCHAUHAN(SR.LECTUR0 DR.ASHISH MAHESHAWARI (SR.LEC.) Presented by - DR.LEENA GANGIL PG FIRST YEAR STUDENT 2015-2018 BATCH

CONTENTS • INTRODUCTION • SYNONYM OF TMJ• COMPONENT OF TMJ• DEVELOPMENT OF TMJ• SURGICAL ANATOMY OF TMJ MANDIBULAR FOSSA ARTICULAR DISC CONDYLE SYNOVIAL MEMBRANE SYNOVIAL FLUID LIGAMENTS 

• MOVEMENT OF TMJ 

• INNERVATIONS,VASCULARIZATION,LYMPHATICS OF TMJ 

• EXAMINATION OF TMJ 

• APPLIED ANATOMY 

• CONCLUSION 

• REFERANCES

INTRODUCTION• The Temporomandibular joint is that which connects the mandible to the skull

and regulates mandibular movement.

• The most important functions of the temporomandibular joint (TMJ) are mastication and speech and are of great interest to maxillofacial surgeon.

• The TMJ is a ginglymoarthrodial joint, a term that is derived from ginglymus, meaning a hinge joint, allowing motion only backward and forward in one plane, and arthrodial, meaning a joint of which permits a gliding motion of the surfaces.

• It is a bicondylar joint in which the condyles, located at the two ends of the mandible, function at the same time.

SYNONYMS FOR TMJ Craniomandibular joint -

Cranium (temporal)

Mandibular (condyle) bone

Ginglymoarthroidal joint:-

Ginglymo hinge movements

Arthroidal gliding movements

• It is a synovial joint of condylar variety.

• TMJ is a compound joint ( articular disc acts as a 3rd non ossified bone)

COMPONENT OF TMJ• Bony surfaces – squamous part of Temporal bone Mandibular condyle

• Articular disc• Ligaments• Capsule• Associated muscle

DEVELOPMENT OF TMJ •The TMJ develops from mesenchyme lying . (intramembranous)•Between the developing mandibular condyle below and the temporal bone above.•During the 10th week of IU life ,•Two clefts appear in the mesenchyme –producing the upper and lower joint cavities.

•The remaining intervening mesenchyme becomes the intra – articular disc.The joint capsule develops from a condensation of mesenchyme surrounding the developing joint

•Mandibular fossa is flat at birth and there is no articular eminence , this becomes prominent only following the eruption of the decidous dentition.

 SURGICAL ANATOMY •The articular space of each tmj is divided into

• upper and lower compartments

because of interposition of the fibrous articular disc bt the temporal bone and mandible.

•Glinding or translatory movements occur primarily in the upper compartment ,

• lower compartment functions primarily as hinge or rotary joint.

Tmj has two articular surfaces –

UPPER ARTICULAR SURFACE : articular eminence of temporal bone, mandibular fossa or glenoid fossa

Articular eminence( Anterior convex part )consists of thick, dense bone & is more likely to tolerate such forces.

Posterior roof of mandibular fossa (posterior concave part) is thin ,indicating that this area of temporal bone is not designed to sustain heavy forces.LOWER ARTICULAR SURFACE : head of condyle of mandible

E: Articular eminence; enp: entogolenoid process; t:articular tubercle; Co: condyle; pop: postglenoid process; lb: lateral border of the mandibular fossa; pep: preglenoid

plane; Gf: glenoid fossa; Cp: coronoid process

GLENOID FOSSA or MANDIBULAR FOSSA• Its anterior wall is built by the articular eminence of the squamous

temporal bone and its posterior wall by tympanic plate of temporal bone,which also forms the anterior wall of the external acoustic meatus.

• the term articular fossa refers to the particular portion of glenoid fossa that is covered by articular tissues.

• The articular fossa is built entirely by the squamous portion of temporal bone. The posterior part of the articular fossa is elevated to a ridge called the posterior articular lip.

• The posterior articular lip is higher & thicker at its lateral end and thus visible from the side as a cone shaped process bt the articular fossa and the tympanic plate. This structure is the post glenoid process.

•In the posterior & lateral parts of the glenoid fossa, a fissure separates the articular and non articular portions of the glenoid fossa. This fissure ,called the tympanosqamosal fissure.

•Medial to this fissure ,a bony plate of the petrous portion of the temporal bone, the tegmen tympani, protrudes between the tympanic & squamous portions.

•Therefore ,instead of a tympanosquamosal fissure along the medial aspect of glenoid fossa,an anterior petrosquamousal fissure & a posterior petrotympanic fissure occur.

•The petrotympanic fissure is slightly widened laterally to permit passage of chorda tympani nerve & ant tympanic blood vessels.

•These neurovascular structures are located within the the glenoid fossa,but not with in the articular fossa .

•The articular eminence is the transverse bar of dense bone that forms the posterior root of zygomatic arch & the anterior wall of the articular fossa.

•Lateral to the articular eminence , a small bony projection ,the articular tubercle,is located. It serves as the attachment area for portions of the temporomandibular ligament (TML). 

ARTICULAR DISC – BICONCAVE OVAL STRUCTURE

•Consists of dense collagenous tissue that is avascular and devoid of nerve tissues in the central area but has vessels and nerves in the peripheral area.

•It serve as non ossified bone that permits complex movements of the joint .

•Disc divides articular space into 2 compartments :

1. UPPER OR SUPERIOR COMPARTMENT

2. LOWER OR INFERIOR COMPARTMENT

Articular disc divided into 3 regions : (saggital plane)

1. Intermediate zone – thinnest 2. Ant. Band – slightly thicker3. Post. Band – thickest

• During movement the disc is flexible to some extent and can adapt to the functional demands of the articular surfaces.

• The disc maintains its morphology unless destructive forces or structural changes occur in the joint.

• If these changes occur , the morphology of the disc can be irreversibly altered producing biomechanical changes during function.

ATTACHMENTS OF DISC -• RETRODISCAL TISSUE - posterior attachment highly vascularized Superior retrodiscal lamina – elastic fibres Inferior retrodiscal lamina - collagenous fibres.

Remaining – large venous plexus which fills with blood as condyle moves forward.

• ANTERIORLY–superior and inferior attachments of the disc– capsular ligament

• SUPERIOR ATTACHMENT –articular surface of temporal bone

• INFERIOR ATTACHMENT – articular surface of condyle

• It is Composed of collagen fibres

• Between the capsular ligament attachment – superior lateral pterygoid muscles.

• Capsular ligament attachment - medially and laterally also – dividing joint into 2 cavities.

Superior cavity – mandibular fossa and superior surface of disc.

Inferior cavity –mandibular condyle and inferior surface of disc

• The internal surface of the cavities are surrounded by specialized endothelial cells that form a synovial lining.• This lining along with a specialized synovial

fringe located at the anterior border of the retrodiscal tissue produces synovial fluid which fills both the joint cavitie.

• Medium for providing metabolic requirements to the non vascular articular surface of the joint.

CONDYLEBarrel shape – measuring – 20mm – mediolateral , 10mm – anteroposterior • Perpendicular to ascending ramus of the mandible• Oriented 10 – 30 degrees with frontal plane.Medial pole more prominent than lateral poleArticular surface of Posterior aspect > anterior aspect

pA

• In the frontal view – articular eminence often is concave and fits roughly to superior surface of condyle .

•Bony surface of condyle and articular part of the temporal bone – covered with dense fibrous connective tissues with irregular cartilage like cells.

•The number of cells increases with age and stress on the joint.

SYNOVIAL MEMBRANE• lines TMJ cavity internally

• Outer flattened endothelial like cells resting on vascular connective tissue.

• Connective tissue show mainly two types of cells- fibroblast like ( B cells) --rich in RER- macrophage like( A cells)-- rich in Golgi

SYNOVIAL FLUID Having proteoglycans and some mucin which act as lubricant.

Volume-- 1 ml in inf joint space ,Slight more in upper joint space

Viscosity is higher than blood

synovial fluid ( a mechanism to provide nutrition to avascular discal tissue)

Lubricant between articular surfaces during function.

The two mechanisms by which synovial fluid lubricates are -

• Boundary lubrication

• Weeping lubrication

BOUNDARY LUBRICATION• Occurs when joint is moved and synovial fluid is

forced from one area of cavity into another.

• The synovial fluid located in the border or recess areas is forced on the articular surface thus providing lubrication.

WEEPING LUBRICATION

• Refers to the ability of articular surfaces to absorb a small amount of synovial fluid.

• During function of a joint , forces are created between the articular surfaces

• These forces drive a small amount of synovial fluid in and out of articular tissues.

• This is the mechanism by which metabolic exchange occurs.

• Under compressive forces therefore, a small amount of synovial fluid is released.

• This synovial fluid acts as a lubricant between articular tissues to prevent sticking.

• Weeping lubrication helps eliminate friction in compressed but not a moving joint.

• Only a small amount of friction is eliminated by weeping lubrication.

LIGAMENTS

•Ligaments play an important role in protecting the structures.

•The ligaments of the joints are made up of collagenous connective tissue,which do not stretch.

•They do not enter actively into joint function but instead act as a passive restraining devices to limit and restrict border movements.

THREE FUNTCIONAL LIGAMENTS support the TMJ :

•COLLATERAL LIGAMENTS

• CAPSULAR LIGAMENT •TM LIGAMENT

TWO ACCESSORY LIGAMENTS

• SPHENOMANDIBULAR LIGAMENT

• STYLOMANDIBULAR LIGAMENT

COLLATERAL (DISCAL) LIGAMENTS

• Attach the medial and lateral borders of the articular disc to the poles of the condyle

• Commonely called as discal ligaments – medial and laterlal

• Medial discal ligament – attaches the medial edge of the disc to the medial pole of the condyle.

• Lateral discal ligament – attaches the lateral edge of the disc to the lateral pole of the condyle,

• These ligaments are responsible for dividing the joint mediolaterally into the superior and inferior joint cavities.

• The discal ligaments are true ligaments ,composed of collagenous connective tissue fibres , therefore they do not stretch.

• They allow the disc to move passively with the condyle as it glides anteriorly and posteriorly on the articular surface of the condyle

• Thus these ligaments are responsible for the hinging movement of the TMJ , which occurs between the condyle and the articular disc.

• These ligaments have a vascular supply and are innervated .

• Strain on these ligaments produces pain.

CAPSULAR LIGAMENT• The entire TMJ is surrounded and encompassed by the capsular

ligament .

• The fibres of the capsular ligament are attached superiorly to the temporal bone along the borders of the articular surface of the mandibular fossa and articular eminence .

• Inferiorly the fibers of the capsular ligament attach to the neck of the condyle.

• The capsular ligament -resist any medial, lateral or inferior forces that tend to separate or dislocate the articular surfaces.

• One significant function – to encompass the joint thus retaining the synovial fluid.

• Capsular ligament is well innervated and provides proprioceptive feedback regarding position and movement of joint .

TEMPOROMANDIBULAR LIGAMENT

The lateral aspect of the capsular ligament is reinforced by strong , tight fibres – lateral ligament or TM ligament. TM ligament has 2 parts • Outer oblique portion• Inner horizontal portion

 

• Outer portion – extends from outer surface of the articular tubercle and zygomatic process postero-inferiorly to the outer surface of the condylar neck.

• Inner horizontal portion – extends from the outer surface of the articular tubercle and zygomatic process posteriorly and horizontally to the lateral pole of the condyle and posterior part of articular disc.

• Function of outer oblique portion – resists excessive drooping of the condyle – limiting the extent of mouth opening.

• During the initial phase of opening ,the condyle can rotate around a fixed point until the TM ligament becomes tight as its point of insertion on the neck of the condyle is rotated posteriorly.

• When the ligament is taut, the neck of the condyle cannot rotate further .

• If mouth were to be opened wider- the condyle has to move downward and forward across the articular eminence.

• Clinically tested by – closing the mouth and applying mild posterior force to the chin-jaw easily rotates until teeth are 20 – 25mm apart after which a resistance is felt when the jaw is opened wider.

• This resistance is brought about by the tightening of TM ligament.

This unique feature of TM ligament which limits rotational opening is found only in humans.

• The inner horizontal portion of TM ligament limits posterior movement of condyle and disc.

• When force applied to the mandible it displaces the condyle posteriorly , this portion of ligament becomes tight and prevents the condyle from moving further into the posterior region of the mandibular fossa.

• Hence it protects the retrodiscal tissues from trauma created by posterior displacement of the condyle.

• Also protects the lateral pterygoid muscle from overextension or overlengthening.

• The effectiveness of TM ligament is demonstrated during cases of extreme trauma to the mandible.

 

SPHENOMANDIBULAR LIGAMENT

• Accesory ligament of the TMJ

• Arises from the spine of the sphenoid bone and extends downwards to a small bone prominence on the medial surface of the ramus of the mandible called the lingula.

• It does not have any significant limiting effects on mandibular movement.

 

STYLOMANDIBULAR LIGAMENT

• It arises from the styloid process and extends downwards and forward to the angle and posterior border of the ramus of the mandible.

• It becomes taut when the mandible is protruded but is most relaxed when the mandible is opened.

• The stylomandibular ligament therefore limits the excessive protrusive movements of the mandible.

 MOVEMENTS OF TMJ

Movements

• Rotational / hinge movement in first 20-25mm of mouth opening

• Translational movement after that when the mouth is excessively opened.

 

• Translatory movement – in the superior part of the joint as the disc and the condyle traverse anteriorly along the inclines of the anterior tubercle to provide an anterior and inferior movement of the mandible.

Muscle producing movements•DEPRESSION –Lateral pterygoidDiagastricGeniohyoidMylohyoid

•ELEVATION –MasseterTemporalisMedial pterygoid

Posterior fibers of diagastric

SIDE TO SIDE MOVEMENT –Turning the chin to the left side produced by the left lateral pterygoid & right medial pterygoid & vice versa.

•PROTRUSION –Lateral pterygoidMedial pterygoid

•RETRUSION –Posterior fibers of temporalis

RELATIONS –Anteriorly -

Mandibular notch Lateral pterygoidMasstric nerve and vessels 

• A careful dissection of 16 intact human cadaveric head specimens revealed The location of the masseteric artery was then determined in relation to 3 points process:

1) the anterior-superior aspect of the condylar neck = 10.3 mm; 2) the most inferior aspect of the articular tubercle = 11.4 mm; 3) the inferior aspect of the sigmoid notch = 3 mm

LATERALY

•Skin and fascia

•Parotid gland

•Temporal branch of facial nerve

POSTERIORLY -

Parotid glandSuperficial temporal vesselsAuriculotemporal nerve

Medially –• Tympanic plate (separates from ICA)• spine of sphenoid• Auriculotemporal & chorda tympani nerve• middle meningeal artery

SUPERIORLY –middle cranial fossamiddle meningeal vessels Inferiorly – maxillary artery & vein

 

•Most innervation is provided by the auriculotemporal nerve as it leaves the mandibular nerve behind the joint and ascends laterally and superiorly to wrap around the posterior region of the joint

• Additional innervations by – deep temporal and massetric nerve.

INNERVATION OF TMJ

VASCULARIZATION OF TMJ

Predominant vessels are • Superficial temporal artery - from the posterior

• Middle meningeal artery - from the anterior

• Internal maxillary artery – from the inferior

•

Other important arteries are – the deep auricular , anterior tympanic and ascending pharyngeal arteries.

• The condyle – through marrow spaces by way of the inferior alveolar artery .

LYMPHATICS OF TMJ

Mainly into PAROTID LYMPH NODES Also drain into:- • Preauricular lymph nodes • Submandibular lymph nodes 

Examination of TMJ & its evaluation •Clinical functional analysis

•Muscle examination

•Mandibular movement analysis

•Temporomandibular joint examination

• - joint pain

• - joint dysfunction

Radiographic techniques

- OPG

- Transcranial view

- transpharyngeal view

- A.P View

- C.T

- M.R.I

 

FUNCTIONAL EXAMINATIONA OF TMJ •Objectives To asses severity of clicking pain and dysfunction, which are characterized by pathological symptoms.Clinical examination• Auscultation• Palpation

1.Auscultation –When auscultation is carried out with stethoscopes clicking & cripitus in the joint may be diagnosed during anteroposterior & eccentric movement of mandible. 

2. Palpaltion –Palpation of tmj during opening and closing which reveals possible pain on pressure of condylar area.

Methods of palpation –1) Pretragus (lateral palpation of tmj)

Exert slight pressure on the condyle of mandible with index fingers.Palpate both side simultaneously .

Register any tenderness to palpation of joints & irregularities in condylar movement during opening & closing

 

PALPATION OF MASTICATORY MUSCLES:

• An accepted method of determining muscle tenderness or pain is to use the fingers tips of the middle & index finger to palpate specific anatomic sites.

• It has been proposed that 2 lb of digital pressure on extraoral muscles & 1lb of pressure on intraoral areas held for 3 to 5 seconds are appropriate.

TEMPORALIS –Palpated by placing thumb behind the eye , 1st finger on the middle belly and 2nd finger near the coronoid process in front of meatus.  

MASSETER –

Palpated by asking the patient to close the mouth forcefully , anterior fibers are then visible .

Deep fibers can be palpated deep to the zygomatic bone.

 LATERAL PTERYGOID

• Superior fibers are palpated by placing finger near the lateral poles of condyle and lower fibers are palpated by running the finger buccally and behind the maxillary tuberosity.

MEDIAL PTERYGOID

Palpated by placing the finger near the lower part of medial surface of ramus of mandible.

AGE CHANGES OF THE TMJ:

• Condyle:

– Becomes more flattened

– Fibrous capsule becomes thicker.

– Osteoporosis of underlying bone.

– Thinning or absence of cartilaginous zone.

• Disk:

– Becomes thinner.

– Shows hyalinization and chondroid changes.

• Synovial fluid:

Become fibrotic with thick basement membrane.

• Blood vessels and nerves:

Walls of blood vessels thickened.

• Nerves decrease in number

• These age changes lead to : -Decrease in the synovial fluid formation

-Impairment of motion due to decrease in the disc and capsule extensibility

-Decrease the resilience during mastication due to chondroid changes into collagenous elements

-Dysfunction in older people

APPLIED ANATOMY –

Temporomandibular disorders (TMD)

•These are a class of degenerative musculoskeletal conditions associated with morphologic and functional deformities.

•The joint may not only involved in the inflammatory pathologies,but also involved secondary to the stress and psychological disorders due to mandibular parafunction.

1.TMJ ANKYLOSIS –Ankylosis is a greek terminology meaning “ stiff joint”.

Tmj ankylosis is the pathological fusion between the glenoid fossa of temporal bone and the condylar process of the mandible.

Etiology of ankylosis -

1.Trauma –a)Fall on the chin leading to indirect injuries to tmj like hemarthosis, contusion .b) intra capsular & extra capsular fracture of condylec) birth trauma – application of forceps during labor

2. Infections -• Middle ear infections • Septic fractures of condyle, zygomatic arch• Osteomyelitis of condyle• Mastoiditis• Hematogenous infections• Specific infections – tuberculosis, syphilis, actinomycosis

etc.

3. Inflammatory joint pathologies –• Osteoarthritis• Rheumatoid arthritis• Rheumatic arthritis

 classification – According to kazanjian TRUE ANKYLOSIS OR INTRA ARTICULAR ANKYLOSIS• Fibrous• Bony

 FALSE OR EXTRA ARTICULAR ANKYLOSIS• Fusion of coronoid process with zygomatic arch

OTHER REASON OF FALSE ANKYLOSIS•Muscle fibrosis•myositis ossificans•oral submucous fibrosis •neurogenic ( tetnus,tetany)•malignancy ,•Depressed zygomatic fracture etc

UNILATERAL ANKYLOSIS –• Deviation of the mandible &chin on affected side .

• Roundness or fullness of face on affected side,flatness or elongation of face on the unaffected side.

• Well defined antegoinal notch on affected side.

• Cross bite & some amount of incisal opening may be possible

• A bony thickening is often felt in the preauricular area of the affected TMJ.

CLINICAL FEATURES-

BILATERAL ANKYLOSIS• The mandible is symmetrical but micrognathic.

• Pt has typical bird face deformity with receded chin.

• The neck chin angle may be reduced or almost completely absent.

• Antegonial notch is well defined bilaterally

• Cl II malocclusion ,upper incisors are proclined with anterior open bite .

• Oral opening will be less than 5 mm or nil oral opening

• Multiple carious teeth ,periodontally compromised,malocclusion,multiple impacted teeth.

TREATMENT MODALITIES

• Brisement force• Condylectomy• Gap arthoplasty• Interpositional arthoplasty with reconstruction of the

joint

CLINICAL CONSIDERATIONS

SURGICAL APPROACHES TO TMJ

 

•POST/ RETRO AURICULAR

•SUBMANDIBULAR or RISDON’S APPROACH

HEMICORONAL INCISION

•ENDAURAL

POSTRAMAL / HIND’S INCISION

.

• PREAURICULARTHOMA’S ANGULATED INCISION

PREAURICULAR DINGMAN’S INCISION

BLAIR’S INVERTED HOCKYSTICK

ALKAYA- BRAMLEY’S INCISIONINVERTED QUESTION MARK INCISION

• A question mark shaped skin incision which avoids main vessels and nerves

• About 2 cm above the malar arch, the temporalis fascia splits into 2 parts, which can be easily identified by fat globules between 2 layers which form an important landmark.

• In this, temporal facia and superficial temporal artery are reflected with skin flap. Later helps in better healing of the flap.

• Under no circumstances should the inferior end of the skin incision be extended below the lobe of the ear as it increases the risk of damage to main trunk of facial nerve.

• It is particularly important in children where it may be quite superficial.

 

• INTRA ORAL APPROACH: it was described by sear (1972) for removal of hyperplastic condyles.

• The incision commences at the level of upper occlusal plane and passes downwards and forwards between the internal and external oblique ridges of mandible and then forwards as necessary along mandibular body.

• Upper end should not be extended beyond the level of upper molar teeth, otherwise buccal pad of fat is encountered and prolapses in the wound decreasing the visibility .

MYOFASCIAL PAIN DYSFUNCTION SYNDROME

•Myofascial pain dysfunction (MPD) syndrome is a psychophysiologic disease that primarily involves the muscles of mastication ( laskin 1969).

•The condition is characterized by poorly localized,dull,aching,radiating pain that may become acute during use of the jaw ,and mandibular dysfunction that usually involves a limitation of opening.

•M:f – 1:5

MANAGEMENT – Pharmacological modalitiesIntra- articular injectionsOcclusal splintsPhysiotherapeutic modalitiesStress managementPsychologic modalities Surgical management

ARTHITIS Arthritis is the most frequent pathologic condition affecting the tmj.

TRAUMATIC ARTHRITIS ,(HEMARTHOSIS) The tmj is often subjected to indirect trauma. The fall on the chin thrusts the mandible backward and upward and the

intervening soft tissues like the capsule , meniscus and synovial membrane get contused and undergo inflammation.

The inflammatory reaction makes the joint painful and hypomobile. the effusion of the joint space by the inflammatory exudates and or blood takes place, because of which the condyle gets pushed downwards & produces open bite on the involed side.

DEGENERATIVE ARTHRITIS ( OSTEOARTHRITIS)•Osteoarthritis is a non inflammatory disorder characterized by joint deterioration & proliferation.

•It is associated with aging .

•clinical sign & symptoms are remarkably absent .

•patient may complain of pain on palpation & movements,which is associated with muscle spasm.

•Radiographic features – when the patient is in maximum intercuspation ,the joint space may be narrow or absent.

•flattening of condylar head may be evident.

•Loss of cortex or erosion of articulating surfaces of the condyle or temporal component are characteristic of this disease.

•“Ely cysts” small round radiolucent areas with irregular margins surrounded by increased density, are visible.

•In advanced stage bony proliferation occurs at the periphery of the articulating surface area.

•This new bone which is formed is known as osteophyte.

• The broken osteophytes lie with in the joint space, known as “joint mice”.

RHEUMATOID ARTHRITIS Rheumoid arthritis is an autoimmune inflammatory condition in

which the inflamed &hypertropic synovial membrane grows onto the articulating surfaces.

It is more common in females with increasing age. There is usually bilateral pain,tenderness & swelling & limitation

of jaw motion. TREATMENT FOR ARTHRITIS -

• Pain relief analgesics , NSAIDS corticostroides,physiotherapy,high codylotomy or joint replacement.

DISC CONDYLE INCOORDINATION

1. Hypermobility

2. Subluxation

3. Dislocation

HYPERMOBILITY -

In hypermobility , the jaw opens more than normal,the fibres in the bilaminar zone gets stretched & becomes inflamed , producing pain.

Management include restraining the excessive jaw movements by advising the patient not to open the mouth wide or support the lower jaw at chin ,while yawning.

In severe cases ,elastics can be used to restrain the jaw.

SUBLUXATION -

Later manifestation of hypermobility ,the head of condyle moves ahead of the articular eminence when the patient is able to reduce the condyle in its normal position ,it is known as subluxation.

DISLOCATION –

It is also a step ahead of hypermobility. When the patient is unable to reduce the condyle in its normal position himself ,the condition is described as dislocation.

In acute cases -Management include jaw reduction by moving the mandible slightly anterior ,downward and then backwards ,upwards by holding with thumb on molars .

In chronic dislocation fibrous adhesion develop ,which prevent the reduction,in such cases surgical treatment like eminectomy or condylectomy may be required.

CONCLUSION It is impossible to treatment of jaw movement without an in depth

awareness of the anatomy ,physiology ,and biomechanics of the TMJ.

The first requirement for successful movement of jaw is stable, comfortable TMJ.

The jaw joints must be able to accept maximum loading by the elevator muscles with no signs of discomfort.

It is only through an understanding of how the normal, healthy TMJ functions that we can make sense out of what is wrong when it isn't functioning comfortably.

This understanding of TMJ is foundational to diagnosis and treatment.

REFERENCES -

TEXTBOOK

• Sicher and Dubrul's Oral Anatomy by E. Lloyd Dubrul

• B.D. Chaurassia’s human anatomy 4th edition vol. 3 The Head & Neck.

• Fonseca volume 2 by Robert D. Marciani

• Surgical Approaches To Facial Skeleton By – Edward Ellis III & Nmichael F. Zide

• Gray’s Anatomy• Fundamentals of occlusion and

TMJ disorders -- Okeson

THANK YOU