TEMPOROMANDIBULA

R

JOINT

By – Dr. JJ

Contents INTRODUCTION PECULIARITY OF TMJ COMPONENTS VASCULAR SUPPLY INNERVATIONS RELATIONS MOVEMENTS AGE CHANGES DEVELOPMENT CLINICAL SIGNIFICANCE TMJ DISORDERS CONCLUSION REFERENCES

JOINTS

CLASSIFICATIONS OF JOINTS

STRUCTURAL CLASSIFICATION:

FIBROUS JOINTCARTILAGENOUS JOINTSYNOVIAL JOINT

FUNCTIONAL CLASSIFICATION:

SYNARTHROSIS AMPHIARTHROSESDIARTHROSIS

TEMPOROMANDIBULAR JOINT

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 arthrodia,

meaning a joint of which permits a gliding

motion of the surfaces.

Dorland WA: Medical Dictionary. Philadelphia and London, SaundersCo., 1957

The temporomandibular joint (TMJ), also known as the mandibular joint, is an ellipsoid variety of the right and left synovial joints forming a bicondylar articulation.

The common features of the synovial joints exhibited by this joint include a disk, bone, fibrous capsule, fluid, synovial membrane, and ligaments. However, the features that differentiate and make this joint unique are its articular surface covered by fibrocartilage.

Williams PL: Gray’s anatomy, in Skeletal System (ed 38). Churchill. Livingstone, London, 1999, pp 578-582

Peculiarity of TMJ

1. Bilateral diarthrosis – right & left function

together

2. Articular surface covered by fibrocartilage

3. Only joint in human body to have a rigid

endpoint of closure that of the teeth making

occlusal contact.

4. In contrast to other diarthrodial joints TMJ is

last joint to start develop, in about 7th week in

utero.

5. Develops from two distinct blastema.

Peculiarity of TMJ…….

COMPONENTS

COMPONENTS OF THE TMJMANDIBULAR CONDYLES

ARTICULAR EMINENCE

MUSCLES OF THE TMJ:

MUSCLES OF MASTICATION

SOFT TISSUE COMPONENTS:

ARTICULAR DISC

JOINT CAPSULE

LIGAMENTS

THE MANDIBULAR CONDYLE

An ovoid process seated atop a narrow mandibular neck. It’s the articulating surface of the mandible.

It is convex in all directions but wider latero-medially (15 to 20 mm) than antero-posteriorly (8 to 10mm).

It has lateral and medial poles:

The medial pole is directed more posteriorly.

Thus, if the long axes of two condyles are extended medially, they meet at approximately the basion on the anterior limit of the foramen magnum, forming an angle that opens toward the front ranging from 145° to 160°

Cranial Componentor

Articular surfaces of Temporal bone

The articular surface

of the temporal bone

is situated on the

inferior aspect of

temporal squama

anterior to tympanic

plate.

Articular eminence: This is the entire transverse bony bar that forms the anterior root of zygoma. This articular surface is most heavily traveled by the condyle and disk as they ride forward and backward in normal jaw function.

Articular Disc

The articular disc is the most important anatomic structure of the TMJ.

It is a biconcave fibrocartilaginous structure located between the mandibular condyle and the temporal bone component of the joint.

Its functions to accommodate a hinging action as well as the gliding actions between the temporal and mandibular articular bone.

The articular disc is a roughly oval, firm, fibrous plate.

• It is shaped like a peaked cap that divides the joint into a larger upper compartment and a smaller lower compartment.

Hinging movements take place in the lower

compartment and gliding movements take

place in the upper compartment.

The disc is attached all around the joint

capsule except for the strong straps that fix

the disc directly to the medial and lateral

condylar poles, which ensure that the disc

and condyle move together in protraction

and retraction.

Williams PL: Gray’s anatomy, in Skeletal System (ed 38). ChurchillLivingstone, London, 1999, pp 578-582

Fibrous Capsule

Thin sleeve of tissue completely surrounding the joint.

Extends from the circumference of the cranial articular surface to the neck of the mandible.

Patnaik VVG, Bala S,Singla Rajan K: Anatomy of temporomandibular joint A review. J Anat Soc India 49(2):191-197, 2010

Anteriorly, the capsule has an orifice through

which the lateral pterygoid tendon passes. This

area of relative weakness in the capsular lining

becomes a source of possible herniation of intra-

articular tissues, and this, in part, may allow

forward displacement of the disc.

Temporomandibular Ligaments Complex

Collateral Ligaments

The ligament on each side of the jaw is designed in two distinct layers.

The wide outer or superficial layer is usually fan-shaped and arises from the outer surface of the articular tubercle and most of the posterior part of the zygomatic arch.

There is often a roughened, raised bony ridge of attachment on this area.

Sphenomandibular Ligament

Arises from the angular spine of the sphenoid and petrotympanic fissure.

Runs downward and outward.

Insert on the lingula of the mandible.

The ligament is related –1. Laterally - lateral pterygoidmuscle.2. posteriorly - auriculotemporal

nerve.3. anteriorly - maxillary artery.4. Inferiorly - the inferior alveolar

nerve and vessels a lobule of the parotid gland.

5. Medially - medial pterygoid with the chorda tympani nerve and the wall of the pharynx with fat and the pharyngeal veins intervening.

The ligament is pierced by the myelohyoid nerve and vessels.

Stylomandibular Ligament

This is a specialized dense, local concentration of

deep cervical fascia extending from the apex and

being adjacent to the anterior aspect of the styloid

process and the stylohyoid ligament to the

mandible’s angle and posterior border.

Other ligaments

Oto mandibular ligament Disco malleolar ligament Mallelo mandibular ligament

Lubrication of the Joint

The synovial fluid comes from two sources:

first, from plasma by dialysis, and second, by

secretion from type A and B synoviocytes with a

volume of not more than 0.05 ml.

Synovial fluid…… It is clear, straw-colored viscous fluid. It diffuses out from the rich cappillary

network of the synovial membrane.

Contains: Hyaluronic acid which is highly viscous May also contain some free cells mostly

macrophages.

Functions: Lubricant for articulating surfaces. Carry nutrients to the avascular tissue of the

joint. Clear the tissue debris caused by normal

wear and tear of the articulating surfaces.

Muscular Component The masticatory muscles surrounding the joint are

groups of muscles that contract and relax in harmony so that the jaws function properly.

When the muscles are relaxed and flexible and are not

under stress, they work in harmony with the other parts of the TMJ complex.

The muscles of mastication produce all the movements of the jaw.

These muscles begin and are fixed on the cranium extending between the cranium and the mandible on each side of the head to insert on the mandible.

MUSCLES OF MASTICATION

Moves mandible - mastication &

speech

1.Masseter

2.Temporalis

3.Lateral pterygoid

4.Medial pterygoid

MUSCLES – INSERTION – NERVE SUPPLY- ACTIONS

Masseter superficial layer Elevates

middle layer mandible deep layer

Temporalis temporal fossa elevates

temporal fascia grinding

MUSCLES – INSERTION – NERVE SUPPLY - ACTION

Lateral pteryoid upper head depression

lower head protrusion grinding

Medial pterygoid superficial head elevates

deep head protrusion

Teeth and Occlusion

The way the teeth fit together may affect the TMJ complex.

A stable occlusion with good tooth contact and interdigitation provides maximum support to the muscles and joint, while poor occlusion (bite relationship) may cause the muscles to malfunction and ultimately cause damage to the joint itself.

Instability of the occlusion can increase the pressure on the joint, causing damage and degeneration.

VASCULARISATION

Branches of External Carotid Artery Superficial temporal artery Deep auricular artery Anterior tympanic artery Ascending pharyngeal artery Maxillary artery

VASCULARISATION

The Blood supply to TMJ is only Superficial, i.e. there is no blood supply inside the capsule.

Innervation

Sensory innervation of the TMJ

is derived from the

auriculotemporal and

masseteric branches of

trigeminal nerve.

LYMPHATIC DRAINAGE

LATERAL SURFACE : PREAURICULAR AND

PAROTID NODES

POSTERIOR AND MEDIAL SURFACE : SUBMANDIBULAR NODES THROUGH

EXTERNAL CAROTID ARTERY

ANTERIOR SURFACE : PAROTID NODES

RELATIONS

Anteriorly - Mandibular notch Lateral pterygoid Masseteric nerve and artery

RELATIONS

Posteriorly - parotid gland Superficial temporal vessels Auriculotemporal nerve

RELATIONS

Laterally –

Skin and fasciaParotid glandTemporal branches of facial nerve

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

Superiorly –middle cranial fossamiddle meningeal vessels

Inferiorly – maxillary artery & vein

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.

Mouth closed Mouth open

Hinge movement – the inferior portion of the joint between the head of the condyle and the lower surface of the disc to permit opening of the mandible.

1. Depression Of Mandible Lateral pterygoid Digrastric Geniohyoid Mylohyoid

2. Elevation of Mandible Temporalis Masseter Medial Pterygoids

3. Protrusion of Mandible Lateral Pterygoids Medial Pterygoids

4. Retraction of Mandible Posterior fibres of Temporalis

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 fold: 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.

DEVELOPMENT

The mandible develops from Meckel’s

cartilage, which provides the basic support

for the lower jaw and terminates dorsally

into Malleus.

The primary joint exists till the 4th month of

intra uterine life.

At 3 month of gestation the secondary joint

begins to form

Embryologically, the primary jaw joint

between incus & malleus persists in

the fetal period till 4 months of IUL.

It is then replaced by secondary joint,

as incus & malleus recede into middle

ear and initiate sound conduction.

It is phylogenetically replaced by

secondary joint, which is the TMJ.

HISTOLOGY OF TMJ

BONY STRUCTURES:

Condyle- composed of cancellous bone

covered by a thin compact bone

- trabeculae radiate from neck of condyle

Fossa- roof consists of thin layer of

compact bone

Articular eminence- spongy bone

covering thin layer of compact bone

Fibrocartilagenous zone:

- Collagen fibers in bundles forms net work

- resist compressive & lateral forces

Calcified zone:

- deepest zone,chondrocytes &

chondroblasts

- active site for remodelling

Clinical significance

Examination

Disorders

Examination

To palpate the joint and its associated

muscles effectively, have the patient go

through all the movements of the mandible

in relationship to the TMJ while bilaterally

palpating the joint just anterior to the

external acoustic meatus of each ear.

65

This includes asking the patient to open

and close the mouth several times and

then to move the opened jaw to the

left, and then to right, and then

forward.

To further assess the mandible moving

at the TMJ, use digital palpation by

gently placing a finger into the outer

part of EAM.

TMJ DISORDERS

Temporomandibular Joint Disorder

• The disorder and resultant dysfunction can result in significant pain and impairment

• Because the disorder transcends the boundaries between several health-care disciplines in particular,

- Dentistry - Neurology - Physical therapy - Psychology

CLASSIFICATION OF DISORDERS OF TMJ

1. Masticatory Muscle Disorders

a. Protective co-contraction b. Local muscle soreness c. Myofascial pain d. Myospasm e. Centrally mediated myalgia

2. Temporomandibular Joint Disorders A. Derangement of condyle-disc complex a. Disc displacements b. Disc dislocation with reduction c. Disc dislocation without reduction

B. Structural incompatibility of the articular surfaces a. Deviation in form - Disc - Condyle - Fossa b. Adhesions - Disc to condyle - Disc to fossa

c. Subluxation ( hypermobility)d. Spontaneous dislocation

C. Inflammatory Disorders of TMJ a. Synovitis b. Retrodiscitis

c. Arthritides - Osteoarthritis - Osteoarthrosis - Polyarthritides d.. Inflammatory disorders of associated structures a. Temporal tendonitis b. Stylomandibular ligament inflammation

3. Chronic mandibular hypomobility A. Ankylosis - Fibrous - Bony B. Muscle contracture - Myostatic - Myofibrotic C. Coronoid impedance

4. Growth Disorders A. Congenital and developmental bone

disorders a. Agenesis b. Hypoplasia c. Hyperplasia d. Neoplasia

B. Congenital and developmental muscle disorders

a. Hypotrophy b. Hypertrophy c. Neoplasia

.

Predisposing Factors

• Modification of chewing surfaces of the teeth through dental neglect or accidental trauma

• Speech habits resulting in jaw thrusting.

• Excessive gum chewing or nail biting.

• Excessive jaw movements associated with exercise.

• Repetitive subconscious jaw movements associated with bruxing or clenching.

• Size of foods eaten

Signs and Symptoms

• Jaw pain and/or stiffness

• Headaches, usually at the temples and side of head.

• Vague tooth soreness or toothache which often move around the mouth.

• Sensitive teeth

• Painful or tender jaw joint

• Difficulty in opening jaw and ear pain.

• Pain and fatigue when eating hard or chewy foods

Treatment

TMD treatments are conservative and reversible

Treatment

Conservative Treatments

• Conservative treatments are as simple as

possible and are used most often because most

patients do not have severe, degenerative TMD

• Conservative treatments do not invade the tissues

of the face, jaw or joint

Treatment

Reversible treatments do not cause permanent, or

irreversible, changes in the structure or position of the

jaw or teeth.

TMJ Symptom Relief

• It is important to avoid large movement of the jaw

such as singing

and wide yawning.

• Do not apply pressure with your hand against your jaw

for an extended time period during sleep.

TMJ Symptom Relief

Choose soft food and stay away from foods requiring

repetitive chewing or the mouth to open wide. In

particular, avoid chewing gum and raw carrots.

TMJ Symptom Relief

Continue to receive dental treatment for any teeth

requiring restoration. Tooth decay may affect the bite,

a contributing factor to TMJ..

TMJ Symptom Relief

Medications • Non-steroidal anti-inflammatory drugs (NSAIDs like ibuprofen), muscle relaxants, anti-anxiety medications and in some cases anti-depressants.

• The choice of medication depends on the intensity of the disorder and the medical history.

• However, the need for medication is greatly reduced when treatment is received by an experienced TMJ dental professional.

Dental Appliances

TMJ Symptom Relief

• Dentist may prescribe a dental appliance such as

a mouth guard or splint to reduce the effects of

tooth grinding and clenching.

• Such appliances may also help improve your bite

and the ability for the lower jaw to fall properly into

the temporomandibular joint socket.

MOST COMMON TMDs

Myofascial pain and dysfunction Internal derangement Osteoarthrosis Dislocation

MYOFASCIAL PAIN AND DYSFUNCTION

Refers to a group of poorly defined muscle

disorders (eg, fibromyalgia) characterized by

diffuse facial pain and episodic limited jaw opening.

May result from parafunctional habits and

significant relationship to psychophysiologic

disorders such as stress or depression.

INTERNAL DERANGEMENT

Abnormal relationship of the articular disc to

the mandibular condyle, fossa,and articular

eminence, interfering with the smooth action

of the joint (Dolwick 1983).

Is a localized mechanical fault within the

joint.

OSTEOARTHROSIS

Is a non- painful, localized degenerative joint disease

that mainly affects bone and articular cartilage.

It is often idiopathic, but predisposing factors such

as old age, repetitive trauma (bruxism), abnormal

joint posturing, or multiple surgical procedures may

be involved. If painful, then referred to as

osteoarthritis.

ANKYLOSIS

Fusion of the TMJ is the occasionallate outcome of trauma or infection.

Dislocation

EPIDEMIOLOGY TMD mostly affects people in the 20 – 40 age

group, and the average age is 33.9 years.

About 60-70% of the population have

features of TMDs.

About 20-30% report symptoms of TMDs.

About 5% of people with TMD symptoms

actually seek treatment.

The female: male ranges from 3:1• Natl J Maxillofac Surg. 2014 Jan-Jun; 3(1): 25–30.• Prevalence of Temporo-mandibular Joint Disorders in

Symptomatic and Asymptomatic Patients: Int J Adv Sci 2014; 1(6): 14-20

TMJ SURGERY

Indicated for a subset of temporomandibular disorders:

1.Internal derangment; 2.Degenerative joint disease; 3. Rheumatoid arthritis; 4. Infectious arthritis; 5.Mandibular dislocation; 6.Ankylosis; 7.Condylar hyper/hypoplasia

Examples of surgical procedures that are used in

TMD,  arthrocentesis, arthroscopy,

menisectomy, disc repositioning, condylotomy

or joint replacement.

Invasive surgical procedures in TMD may cause

symptoms to worsen.

 Menisectomy, also termed discectomy refers to

surgical removal of the articular disc.

SURGERIES OF THE JOINT

Discectomy Disc repositioning Condylotomy Arthrocentesis Arthroscopy Partial and total joint replacement

Conclusion

• TMJ plays important role in chewing ,

speaking, swallowing etc.

• It is one of most important and most poorly understood of the many joints in the body.

• We are just now beginning to understand it

and give it the respect and careful treatment it

deserves as an integral functioning part of the

dental anatomy.

REFERENCES - TEXTBOOK

1. Sicher and Dubrul's Oral Anatomy by E. Lloyd Dubrul2. The Tmj Book by Andrew S. Kaplan, Jr. Williams Gray 3. B.D. Chaurassia’s human anatomy 4th edition vol. 3 The Head &

Neck.

4. Williams PL: Gray’s anatomy, in Skeletal System (ed 38). Churchill Livingstone, London, 1999, pp 578-582

5. Fonseca volume 2 by Robert D. Marciani6. Temporomandibular Disorder, A Problem Based

Approach by Dr Robin J. M. Gray & Dr M. Diad Al – Ani7. Surgical Approaches To Facial Skeleton By – Edward

Ellis III & Nmichael F. Zide8. Surgery Of TMJ 2nd ed. by David A. Keith

REFERENCES - ARTICLES1. Dorland WA: Medical Dictionary. Philadelphia and London, Saunders Co.,

19572. Williams PL: Gray’s anatomy, in Skeletal System (ed 38). Churchill

Livingstone, London, 1999, pp 578-5823. Yale SH: Radiographic evaluation of the temporomandibular joint. J Am

Dent Assoc 79(1):102-107, 19694. Patnaik VVG, Bala S,Singla Rajan K: Anatomy of temporomandibular joint?

A review. J Anat Soc India 49(2):191-197, 20005. Harms SE, Wilk RM: Magnetic resonance imaging of the

temporomandibular joint. Radiographics 7(3):521-542, 19876. Tallents RH, Katzberg RW, Murphy W, et al: Magnetic resonance imaging

findings in asymptomatic volunteers and symptomatic patients with temporomandibular disorders. J Prosthet Dent 75(5):529-533, 1996

7. Helms CA, Kaplan P: Diagnostic imaging of the temporomandibular joint: recommendations for use of the various techniques. AJR Am J Roentgenol 154(2):319-322, 1990

8. Helms CA, Kaban LB, McNeill C, et al: Temporomandibular joint: morphology and signal intensity characteristics of the disk at MR imaging. Radiology 172(3):817-820, 1989

REFERENCES - ARTICLES

9. Kreutziger KL, Mahan PE: Temporomandibular degenerative joint disease. Part II. Diagnostic procedure and comprehensive management. Oral Surg Oral Med Oral Pathol 40(3):297-319, 1975

10. Toller PA: Temporomandibular capsular rearrangement. Br J Oral Surg 11(3):207-212, 1974

11. McMinn, RMH: Last’s anatomy regional and applied, in Head and Neck and Spine. Churchill Livingstone, Edinburgh, London, 1994, p. 523

12. Roberts D, Schenck J, Joseph P, et al: Temporomandibular joint: magnetic resonance imaging. Radiology 154(3):829-830, 1985

13. Harms SE, Wilk RM, Wolford LM, et al: The temporomandibular joint: magnetic resonance imaging using surface coils. Radiology 157(1):133- 136, 1985

14. Edelstein WA, Bottomley PA, Hart HR, et al: Signal, noise, and contrast in nuclear magnetic resonance (NMR) imaging. J Comput Assist Tomogr 7(3):391-401, 1983

15. Westesson PL, Katzberg RW, Tallents RH, et al: Temporomandibular joint: comparison of MR images with cryosectional anatomy. Radiology 164(1):59-64, 1987

PREVIOUS YEAR QUESTIONS

Muscles of Mastication (RGUHS 2007,20 marks)

Temporomandibular joint (RGUHS 2005, 10 marks)