TEMPOROMANDIBULAR JOINT

Dr. P. Ravisankar, Ph.D.

Professor

Department of Anatomy

SRM Dental College & Hospital

Ramapuram, Chennai-600089,TN. INDIA.

INTRODUCTIONThe temporomandibular joint is the joint of the jaw and is frequently referred to as TMJ. Situated in temporal regionRight and Left – Bicondylarcombined gliding and hinge type of the synovial jointCompound joint

▪ Classification:- (A)typical Synovial joint

▪ variety :- Condylar

COMPONENTS

Mandibular condyles Articular surfaces of temporal bone Capsule Articular disc Ligaments Relations Movements Muscles producing the movements Blood supply, Nerve supply Lymphatic & Venous drainage Applied anatomy References

Anatomy Overview

Articular surfaces

Upper articular surface:-

1.Articular tubercle

2.Anterior part of the Mandibular fossa

(Concavo-convex)

❑ Lower articular surface:-

Head of Mandible (condyle- elliptical)

Articular surfaces are covered by fibrocartilage (not by hyaline)

Articular surfaces

LIGAMENTS Fibrous capsule:-

The capsule is a fibrous membrane that surrounds the joint and incorporates the articular eminence.

Above :-

It is attached to articular tubercle, circumference of the mandibular fossa, squamotympanic fissure

Below :-

Neck of Mandible

SYNOVIAL MEMBRANE

The articular capsule is lined with a synovial membrane that folds to form synovial villi.

Projects into joint spaces. It stretches during movement and remain folded during rest.

It consists of internal cells which do not form continuous layer but shows gaps and the subintimal connective tissue layer ,rich in blood capillaries.

ARTICULAR DISC

❑Oval fibrous(cartilage) plate

❑Divides the joint cavity into upper and Lower compartments

❑Upper – gliding movements

❑Lower –Gliding and rotatory movements

❑Parts:-

Anterior extension,

Anterior thick band

Intermediate zone,

Posterior thick band and bilaminar region

Articular discThe disc divides each joint into two

The lower joint formed by the mandible and the articular disc

Involved in rotational movement-this is the initial movement of the jaw when the mouth opens.

The upper joint formed by the articular disc and the temporal bone

Involved in translational movements-this is the secondary gliding motion of the jaw as it is opened widely.

condyle

disk

tubercle (articular

eminence)

ARTICULAR DISC

Ligaments contd…

Lateral or Temporomandibular ligament:-

Strengthens the lateral part of the capsule.

Above :- articular tubercle

Below :-Posterolateral part of neck of Mandible

Ligaments contd…

Spheno-mandibular ligament:

Above:- Spine of sphenoid

Below:-Lingula of Mandibular foramen

Remnant of dorsal part of Meckel’s cartilage

Pierced by Mylohyoid nerves and vessels

Ligaments contd…

Stylomandibular Ligament:-

Thickened part of investing layer of

Deep cervical fascia

Above:- lateral surface of styloid process

Below:-Posterior border of ramus of mandible

RELATIONS

Lateral:-

1.Skin and fascia

2.Parotid gland

3.Temporal branch of facial nerve

(Subcutaneous)

Relations

❑ Medial:-

1.Tymapnic plate separates from the joint from ICA

2.Spine of spenoid and sphenomandibular ligament

3.Auriculotemporal and chorda tymapni nerves

4.Middle meningeal artery

Relations

Anterior:-

1.Lateral pterygoid (tendon)

2.Masseteric nerve and vessels

❑ Posterior :-

1Post glenoid part of parotid gland

separates the joint from external auditory meatus

2.Superficial temporal vessels

3.Auriculootemporal nerve

Relations

Superior:-

1.Middle cranial fossa

2.Middle meningeal vessels

❑ Inferior :-

1.Maxillary vessels

MOVEMENTS▪ Depression

▪ Elevation

▪ Protrusion (protraction)

▪ Retraction

▪ Side to side movements (Chewing)

▪ It involve two basic movements

▪ Upper compartment

Gliding movement

▪ Lower compartment

Rotational movement (Two axis)

▪ Transverse – Depression & Elevation

▪ Vertical – Side to side movements

Movements and muscles producing it

Depression:

1.Lateral pterygoid muscle

2.Digastric

3.Geniohyoid

4.Mylohyoid

5.Gravity

❑ Elevation:

1.Masseter

2.Temporalis

3. Medial pterygoid

Movements and muscles producing itcontd…

Protrusion /Protraction:-

Lateral and Medial pterygoids

❑ Retraction:-

Posterior fibres of Temporalis

❑ Side to side movement:-

Medial and lateral pterygoids contracts alternatively

❑ Blood supply

Superficial temporal and Maxillary vessels

❑ Nerve supply

Auriculotemporal and Massetric nerves

❑ Lymphatic drainage

Preauricular, deep parotid and upper deep cervical nodes

❑ Venous drainage

APPLIED ANATOMY

❑a. Anterior dislocation

Yawning or taking a large bite, excessive contraction of the lateral pterygoids may cause the heads of the mandible to dislocate anteriorly(pass anterior to the articular tubercles).

In this position, the mandible remains depressed and the person is unable to close his or her mouth.

▪ To reduce dislocation, the condyle must be lowered and pushed back behind the summit of articular eminence into articular disc

▪ The reduction is done by depressing the jaw with thumb placed on the last molar teeth, and simultaneously elevating the chin.

Reduction of TMJ dislocation

❑ b.Temporomandibular joint syndrome

▪ It consists of group of symptoms arising from TMJ and their associated masticatory muscles

▪ Diffuse facial pain – due to spasm of masseter muscle

▪ Headache – due to spasm of temporalis

▪ Jaw pain – due to spasm of lateral pterygoids

TMJ may also accompany fractures of the mandible.

❑ c. Posterior dislocation is uncommon, Less common - presence of the postglenoid tubercle and the lateral ligament

Injury to articular branches of the auriculotemporal nerve supplying the TMJ, associated with traumatic dislocation and rupture of the articular capsule and lateral ligament, leads to laxity and instability of the TMJ.

❑ d. Arthritis of TMJ

▪ The TMJ may become inflamed from degenerative arthritis,

▪ For example. Abnormal function of the TMJ may result in structural problems such as dental occlusion and joint clicking (crepitus).

▪ The clicking is thought to result from delayed anterior disc movements during mandibular depression and elevation.

❑e. Subluxation of jaw

▪ Due to relaxed ligament or to a meniscus –

Clicking or snapping occurs frequently during movements of jaw.

▪ Forward slipping of the condyle and meniscus beyond the articular eminence.

▪ Plication of joint capsule can be done to treat the condition

❑ f. Fracture of the mandible

▪ It may accompanied by dislocation of TMJ

▪ Care must be taken during operation on the joint to preserve facial nerve and auriculotemporal nerve – articular branch – traumatic dislocation and rupture of articular disc.

❑g. Disc displacement▪ The most common disorder of the TMJ is disc

displacement.

▪ The most common cause of TMJ pain is myo-fascial pain dysfunction syndrome, primarily involving the muscles of mastication.

▪ Internal derangements is defined as an abnormal relationship of the disc to any of the other components of the TMJ.

▪ Disc displacement is an example of internal derangement.

▪ TMJ pain remains one of the most reliable diagnostic criteria for temporal arthritis.

❑h. Ankylosis

▪ Pathologic condition where the mandible is fused to the fossa by bony or fibrotic tissues.

▪ Most often results from trauma or infection, but it may be congenital or a result of rheumatoid arthritis.

▪ Chronic, painless limitation of motion occurs.

When ankylosis - leads to arrest of condylar growth, facial asymmetry is common

❑i.Treatment of ankylosis of TMJ

▪ Treatment - condylectomy.

▪ If the ankylosis is intra-articular - an ostectomy of part of the ramus if the coronoid process and zygomatic arch are also affected.

▪ Jaw-opening exercises must be done for months to years to maintain the surgical correction, but forced opening of the jaws without surgery is generally not indicated and is usually ineffective because of bony fusion.

SURGERIES OF THE JOINT

Discectomy

Disc repositioning

Condylotomy

Arthrocentesis

Arthroscopy

Partial and total joint replacement

REFERENCES1.TEXT BOOK OF ANATOMY 3rd VOLUME 3rd

ED. VISHRAM SINGH

2. GRAY’S ANATOMY 40th ED. – SUSAN & SANDRING

3. BD CHAURASIA’S HUMAN ANATOMY 3rd VOLUME, 8th ED- KRISHNA GARG

4. CLINICALLY ORIENTED ANATOMY

3rd ED. KEITH L.MORE

Thank you…