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temporomandibular joint
- 1. TEMPOROMANDIBULAR JOINT & MUSCLES OF MASTICATION
- 2. CONTENTS • Introduction • Temporomandibular Joint – Evolution – Embroyology – Anatomy – Histology • Muscles Of Mastication • Biomechanics • Temperomandibular Disorders • Conclusion • References
- 3. JOINT • Jointis a junction between two or more bones & is responsible for movement, growth or transmission of forces. • Classification Based on function Synarthosis Diarthosis
- 4. Synarthrosis Fibrous Suture Syndesmosis Gomphosis Cartilagenous Primary Secondary
- 6. Diarthosis - Synovialjoint • Permits significant movement • Features: - 2 bones (articular surface covered by hyaline cartilage) - capsule - synovial fluid • Classified based on shape of articular surfaces
- 7. TEMPOROMANDIBULAR JOINT Socalled a temporomandibular joint as the involving bones are the mandible & the os temporale. Synonyms: Compound system Synovial joint Ginglymo arthrodial joint, Diarthoidal joint
- 8. Evolution • Amphibianskull: Confinement of teeth to dentary bone. • Articulation : between the terminal portion of the meckel’s cartilage (articulare) & palatoquadrate bar. • Reptile skull: Joint in the same palatoquadrate & articulare but dentary joint is increased in size.
- 9. • Mammal likereptile fossil: – Dentary is increased greatly & possess a coronoid process. – Jaw articulation is still the same. • Mammals: Dentary articulates with the temporal bone.
- 10. Embryology of TMJ • Ontogenetically & Phylogenitically tmj is a secondary joint. • Temperomandibular joint
- 11. • 7th week- Articulation between malleus and incus at the dorsal end of Meckel’s cartilage - PRIMARY JOINT . • 8th week- Membranous Bone laid down in a plate like form lateral to Meckels cartilage. • 10 weeks- evidence of future joint as mesenchyme between the condylar cartilage & developing temporal bone.
- 13. • 12 weeks: 2 mesenchymal condensations Condylar grows dorsolaterally Ossification of temporal blastema Inferior joint cavity Differentiation of condylar into cartilage & Sup.joint cavity Formation of disc
- 14. • 13th week: Condyle and articular disk have moved up into contact with temporal bone. • Remnant of meckels cartilage - sphenomandibular ligament • Full differentiation of all articular surfaces occurs by 4th fetal month.
- 15. Differences Neonatal tmjAdult tmj Mandibular fossa Flat Concave Articular eminence Absent Present
- 16. GENES REQUIRED FORTHE FORMATION OF TMJ • Key gene noted to be expressed in condylar cartilage is INDIAN HEDGEHOG (IHH) Secreted by prehypertrophic chondrocytes that are just entering the differentiation pathway.
- 17. • FGF andFGF receptor (Fgfr) gene families - all stages of bone development. • Fgfr1 – periosteum of the condyle and fossa • Fgfr2 – perichondrium of the condyle and fossa • Fgfr3 - immature chondrocytes of the condyle .
- 18. Pecularities of tmj A. Bilateral diarthosis B. Articular surface covered by fibrocartilage C. Last joint among diarthoidals to begin development D. Development from 2 blastemas Synovial joint( 7th week) TMJ
- 19. Articular surface oftmj • Upper – articulae eminence of mandibular fossa of temporal bone • Lower – condylar process of mandible mandibular fossa of temporal bone condylar process of mandible
- 20. Components of TMJ • Bony components: 1. Mandibular condyle 2. Glenoid fossa 3. Articular eminence
- 22. 1. CONDYLE: •Transversely elliptical in shape • Head is covered with fibro-cartilage-articulates with anterior part of mandibular fossa of temporal bone
- 23.
- 24. Soft tissue componets ARTICULAR DISC: • Dense fibrous connective tissue • Avascular except at the extreme periphery of the disc. • Saggital plane: • Anterior view: – Thick medially corresponding to increased space between condyle & articular fossa
- 25.
- 26. • Between Attachmentsto capsular ligament is tendinous fibres of superior lateral pterygoid • Disc attaches to capsular ligament not only anteriorly & posteriorly but also medially & laterally.
- 27. • Movements oftmj: – Superior cavity: Gliding movement. – Inferior cavity: Rotatory +Gliding movement • Functions of articular disc i. Separation ii. Protection iii. stabilization During functional movements of condyle
- 28. Synovial membrane •Internal surfaces of cavity are surrounded by specialized endothelial cells forming synovial lining. • The lining located at the anterior border of retrodiscal tissue produces synovial fluid.
- 29. Synovial fluid •Ultra filtrate of blood plasma • Clear or pale yellow, viscous, slightly alkaline fluid. • Dialysate of blood that also contains mucin( hyaluronic acid) lymphocytes, monocytes, and macrophages. • Functions a. Nutrition of articular cartilage b. Lubrication of the joint cavity c. Prevents wear & tear.
- 30. character Normal plasmaSynovial fluid Chief content water Hyaluronic acid protein High protein content Low protein content amount 55% of total blood volume 2ml
- 31. Mechanism of lubrication • Primary mechanism of lubrication • Prevents friction in moving joint Boundary lubrication • Facilitates Metabolic exchange • Eliminates small amount of friction in Compressed but not moving joint Weeping lubrication
- 32. Ligaments • Collagenous& act predominantly as restraints to motion of the condyle and the disc. Functional ligaments Accessory ligaments
- 33. FUNCTIONAL LIGAMENTS TemperomandibularCollateral/Discal Capsular
- 34. Temperomandibular ligament •Broad ligament formed due to thickening of lateral part of capsular ligament
- 35. 1. Outer obliqueportion: Resists excessive dropping of condyle during mouth opening Oop resists the impingement submandibular & retromandibular structures..
- 36. 2. Inner horizontalportion: Prevents further posterior movement of condyle into the gleniod fossa Eg: During extreme trauma to mandible, neck of condyle fractures before the retrodiscal tissues are injured.
- 37. Collateral ligament •Syn: Discal ligaments • Possess vascular supply & are innervated. Function: • Gliding & hinging movements
- 38. Capsular ligament •Surrounds the joint. • Attachments:
- 39. • Functions: 1.Resists forces that tend to dislocate the articular surfaces. 2. Retains synovial fluid. 3. Provides proprioception
- 40. ACCESSORY LIGAMENTS Sphenomandibular ligament Stylomandibular ligament
- 41. Sphenomandibular ligament •Derived from fibrous envelope of Meckel’s cartilage of first branchial arch • No significant movement
- 42. Stylomandibular ligament •Formed by thickening of deep fascia • Separates parotid gland from submandibular gland
- 43. HISTOLOGY OF TMJ • 4 distinct zones in the articular surfaces of condyle & mandibular fossa i. Articular zone ii. Proliferative zone iii. Fibro Cartilagenous zone iv. Calcified zone
- 45.
- 46. Blood Supply OfTMJ: • Posteriorly - Superficial temporal A. • Inferiorly - internal MaxillaryA. • Anteriorly - middle meningeal A. Others • Deep auricular artery • Anterior tympanic artery
- 47. Nerve supply: • Branches of mandibular nerve • Auriculotemporal nerve • Deep temporal nerve • Massetric nerve
- 48. Lymphatic drainage: 1.Anterior surface of TMJ -parotid lymph nodes. 2. Posterior & medial surface of TMJ - submandibular lymph node 3. Lateral surface of TMJ - pre auricular and parotid lymph nodes
- 49. Muscles of mastication • Four muscles are present • They are A. Masseter B. Temporalis C. Medial pterygoid D. Lateral pterygoid
- 50.
- 51.
- 52.
- 53. • Applied anatomy a) The motor part of mandibular nerve is tested by asking the patient to clench his teeth and then feeling for the contracting masseter and temporalis muscles. b) If one masseter is paralysed the jaw deviates to paralyzed side on opening the mouth by action of normal lateral pterygoid of opposite side.
- 54.
- 55. Action :- i.Elevates mandible ii. Lateral movements. iii. Retraction: posterior fibres Applied anatomy : • Temporal tendonitis: - sharp headaches at temple joint.
- 56.
- 57. • Nerve supply-medial pteygoid nerve. • Blood supply: Maxillary artery. • Action: i. Elevation ii. protrusion iii. side to side movements
- 58.
- 59. • Applied anatomy Bleeding created by needle puncture in medial pterygoid muscle produces a hematoma followed by fibrosis and subsequent trismus.
- 60.
- 61. • Nerve supply- branch of ant div of madibular nerve • Blood supply: Maxillary artery. • Action- Depression, protrusion & side to side movements
- 62. • When medialand lateral pterygoids of two sides act together they protrude the mandible so that lower incisors project in front of upper. • Upper head - Chewing • lower head - Protrusion.
- 63. • Palpation –Palpateby pressing in a superior, medial, & posterior direction.
- 64. • Sphenomandibularis-5th muscle • Discovered by Dunn et al in the mid 1990s at University of Maryland, Baltimore. • Considered to be a part of temporalis. • Origin- Infratemporal surface of greater wing of sphenoid bone. Insertion-Temporal crest of mandible.
- 65. • Blood supply-From maxillary artery, from vessels of medial pterygoid. • Nerve supply- Not yet determined • Function: Considered as an elevator muscle of mandible
- 66. Temporalis Temporalis, Geniohyoid, Digastric Lateral pterygoid Lateral pterygoid Suprahyoid Masseter Medial & Lateral pterygoid Movements of mandible
- 67. EXAMINATION OF TMJ • Interincisally : 53- 58 mm • Restricted mouth opening: – Mouth opening : < 40 mm – Lateral & protrusive movement:< 8mm
- 68. PALPATION OF TMJ • Pain & tenderness of TMJ is determined by digital palpation when mandible is in both stationary & dynamic movements. • Lateral palpation • Posterior palpation
- 70. AUSCULTATION : Click: single sound with short duration. If loud = popping Crepitus: multiple gravel like sounds.
- 71. GERBER RESILIENCE TEST: Enables to measure the resilience & thickness of the discus articularis. useful to plan possible corrections that is necessary through dental occlusion. Normal range :0.6 to 0.9mm & even up to 1.2mm
- 72. Musculoskeletal stability Interarticular pressure Stabilization of joint: Ligaments
- 73. I. Musculoskeletal stability: Orthopedically Stable joint is when the condyles are in their antero superior position in the glenoid fossa, resulting against posterior slopes of articular eminence with discs properly interposed.
- 74. II. Ligaments: Stabilisethe joint by limiting the movement Ligaments elongate but are not streched Compromising the normal jaw function
- 75. III. Interarticular pressure: • Pressure between the articular surfaces of articular eminence & the condyle • Absence of inter articular pressure results in separation of joints and dislocation
- 76. Functional appliance Increased contractile activity of the LPM Intensification of repetitive activity of the retrodiscal pad Increase in growth stimulating factors Change in trabecular orientation Supplementary lengthening of mandible Additional subperiosteal ossification of posterior border of mandible Additional growth of condylar cartilage OPERATION OF FUNCTONAL APPLIANCES
- 77. TemporomandibularJoint Disorders A.Derangement of condyle -disc complex i) Disc displacements ii) Disc dislocation with reduction iii) Disc dislocation without reduction B. Structural incompatibility of the articular surfaces 1. Deviation in form a. Disc b. Condyle c. Fossa
- 78. 2. Adhesions a.Disc to condyle b. Disc to fossa 3. Subluxation 4. Spontaneous dislocation C. Inflammatory disorders 1. Synovitis/ capsulitis 2. Arthritidis
- 79. 3. Osteoarthritis 4.Polyarthritidis D. Inflammatory disorders of associated structures a)Temporal tendonitis b)Stylomandibular ligament inflammation
- 80. Disc displacement: Causes: • Break down of normal rotation of condyle due to elongation of discal ligaments& inferior retrodiscal lamina resulted from trauma. • Thinning of posterior border of disc predisposes to derangement
- 81. • Displaced condyle positioned anteriorly by lateral pterygoid. • Constant application results in thinning of posterior disc & allows the disc to be displaced more anteriorly. Clinical examination normal range of movements Joint sounds are seen
- 83. • Disc dislocationwith reduction : Disc dislocation: Further elongation of inf.retrodiscal lamina , discal ligament & sufficient thinning of posterior border. Results in slippage of joint. Disc & condyle no longer articulate disc dislocation. If the patient can manipulate to reposition the condyle onto posterior border of disc , disc is termed reduced in nature
- 84. Management: • Reducethe intracapsular pain • Definitive treatment of disc displacement is to reestablish a normal condyle disc relationship. • Anterior positioning appliance by Format . – This appliance is worn 24 hrs a day for3 to 6 months. – Appliance repositions the condyle back into the disc
- 85. Disc displacement without reduction: • Further elongation leads to loss in elasticity of superior retrodiscal lamina & recapturing is difficult. • Anterior positioning appliance - contraindicated because it will aggrevate the condition by forcing the disc even more forward. • Supportive therapy/ surgical therapy is indicated. Deviation in form: • Supportive therapy - Patient education • In case of muscle hyperactivity : stabilization appliance is used.
- 86. Adhesions: When adhesionsare present breaking the fibrous attachment is only definitive treatment It is done by using arthroscopic surgery Subluxation: • Only definitive treatment by surgical alteration of joint i.e, by eminectomy. • Supportive therapy . Spontaneous dislocation: • surgical therapy is indicated
- 87. Conclusion Temporomandibularjoint & Masticatory muscles form the vital part of orofacial system both structurally and functionally. It is crucial for an orthodontist to recognize the musculoskeletal stability of the joint and be aware of problems related to deviation from this point.
- 88. References: • Managementof Temporomandibular Disorders & Occlusion – Jeffrey Okeson III • Principles of Oral and Maxillofacial Surgery- Peterson's Vol 1 • Dentofacial Orthopedics with Functional Appliances – Graber, Rakosi, Petrovic, II ed • Text book of oral histology- Ten cate • Human anatomy – B.D Chaurasias 5th Ed • Grey’s anatomy – 38th edition • Craniofacial development: Sperber • Graber, Vanarsdal, Vig
Editor's Notes
- #4 Synarthosis : permits little if any movement Diarthosis : synovial joint
- #5 Fibrous joint: Two bones are connected by fibrous tissue. Suture: joint which permits little or no movement. histology indicates its function is to permit growth as its articulating surfaces are covered by osteogenic layer –responsible for new bone formation to maintain suture as the skull bones are separated by the expanding brain. Syndesmosis: bony components are some distance apart but still connected by interosseous ligament. Eg:joint b/w radius & ulna Gomphosis: socketed attachment of tooth to bone by fibrous periodontal ligament. Primary cartilage: bone & cartilage are in direct apposition eg: Costochondral junction Secondary: sequence: bone- cartilage-fibrous tissue- cartilage-bone eg: pubic symphysis
- #7 Capsule- thereby creates A joint cavity Planar Ginglymoid (hinged) Pivot Condyloid Saddle Ball & socket
- #8 Generally Presence of Atleast 3 bones = compound but TMJ inspite of having only 2 bones is considered as a compound joint as the articular disc serves as a nonossified bone. Provides hinging movemts in one plane, so called – ginglimoid joint Also provides gliding movements: arthoidal joint Thus technically termed as ginglymoarthoidal joint. Only diarthoidal joint with growth potential in the articular cartilage.
- #11 Ontogenicall: embroyological. Incudomalleal joint is first formed. Phylogenetic: evolutionary. The primary joint i.e incudo malleal joint is equivalent to jaw joint of reptiles. thus tmj formed now is a sec joint phylogenetically. Tmj:Two blastemas i.e. the condylar and the temporal blastemas will grow separately and approach each other the intervening tissue between them will then form the articular disc
- #14 Temporal appears first & both blastemas are separate Appearance of cleft above condylar – inferior
- #15 Only when such articular contact has been made, do the joint cavities develop, Cavitation occurs by degradation rather than enzymatic liquefaction or cell death.
- #16 Articular eminence becomes prominent only after eruption of deciduous teeth
- #17 The condyle is an important growth site in the mandible with similarities to the growth plate of the long bones, and it displays four distinct zones: a fibrous cell layer, a progenitor cell layer, a zone of flattened chondrocytes, and a zone of hypertrophic chondrocytes Ihh plays an indirect role in regulating the rate of chondrocyte differentiation by acting in a negative feedback loop with a second secreted protein, parathyroidhormone-related protein (PTHrP), in the periarticular perichondrium Ihh, in conjunction with PTHrP, plays a crucial role in organizing the growth plate
- #18 The transcription factor Sox9 was highly expressed in proliferating chondrocytes in the condyle and has an essential role in cartilage development
- #19 Synovial joint with 1 blastema
- #23 Medial pole more prominent Mediolateraally:18-23mm Antero postero width:8-10mm
- #24 Posterior:Greater articular surface
- #25 Saggital plane:central thin zone- intermediate zone Thick anterior & posterior zones Posterior is slightly thicker
- #26 Superiorly - elastic fibers, -superior retrodiscal lamina . Attaches the articular disc posteriorly to the tympanic plate. Inferiorly - cheifly collagen fibres - inferior retrodiscal lamina. Attaches the disc to the posterior margin of the articular surface of the condyle. The remaining body of the retro discal tissue is attached posteriorly to a large venous plexus, which fills with blood as the condyle moves forward. The superior and inferior attachment of the disc anteriorly is to the capsule. Superiorly it is attached to the anterior margin of the articular eminence and inferiorly it is to the anterior margin of the articular surface of the condyle. Both of these are made up of collagen fibers. Between Attachments to capsular ligament is tendinous fibres of superior lateral pterygoid
- #28 Divides joint space into superior cavity:mandibular fossa & superior surface of the disc Inferior cavity: mandibular condyle & inferior surface of disc
- #29 At birth it covers all internal surfaces but it is lost from articular surfaces as function commences. The flexibility of the inner surface of the capsule is increased by villi of the synovial membrane which disperse the synovial fluid
- #30 Dialysate: fluid that passes through membranes. (since articular surfaces are avascular) The non-vascularized tissues of the joint are dependent on synovial fluid for nutrition. Hence, the thinner mid-portion of the disc and the articular cartilage covering the condyle, fossa and eminence are dependent on the pumping of synovial fluid.
- #31 Normal total blood volume is 5 litres.
- #33 Ligaments associated with the TMJ are composed of collagen, which do not stretch and.
- #35 Superiorly - to articular tubercle on the root of zygomatic bone Inferiorly –posteriolateral border of neck of mandible.
- #36 Outer oblique portion: Normally a condyle rotates around a fixed point until the TM ligament becomes tight at the point of insertion . After this to provide further mouth opening the condyle has to translate downwards & forward across articular eminence. 2nd point: If only rotation occurs there will be damage to the
- #37 Whenever force is applied to mandible, condyle displaces posteriorly. This ligament is tightened& prevents further posterior movement of condyle into the gleniod fossa protecting the retro discal tissue injury
- #38 These ligaments attach the articular disc to the medial and lateral poles of the condyle Medial:attaches medial edge of disc to medial pole of condyle Allows movement of the disc passively with condyle as it anteriorly & posteriorly Responsible for hinging movement of the TMJ , which occurs between the condyle & articular disc.
- #39 Superiorly – temporal bone along the borders of articular surfaces of fossa & eminence. Inferiorly – attached around the neck of the mandible Anteriorly- blends with insertion of lateral pterygoid muscle
- #40 2. In the joint cavities 3. As well innervated
- #42 Superiorly – spine of sphenoid Inferiorly – lingula of the mandible
- #43 Extends from tip of the styloid process of temporal bone to the angle of the mandible Function: limits excessive protrusive movements.
- #45 Articular zone Found adjacent to the joint cavity & outermost functional surfac Made up of dense fibrous connective tissue & collagen fibrous is arranged in bundles – arranged parallel to articular surface Tightly packed to withstand the force of mastication Proliferative zone Mainly cellular Undifferentiated mesenchymal tissue is found Responsible for the proliferation of articular cartilage in response to the functional demands placed on articular surface. Fibrocartilaginous zone Collagen fibrils are arranged in bundles in crossing pattern Offers resistance against compressive & lateral forces Calcified cartilage zone: Made up of chondroblast & chondrocytes {Chondrocytes become hypertropic, die, & have their cytoplasm evacuated forming bone cells from within the medullary cavity The surface of the extracellular matrix scaffolding provides an active site for remodelling activity}
- #46 Anterior- lateral pterygoid muscle, temporalis & massetric nerve & vessels Posterior –parotid gland, superficial temporal vessels, auriculotemporal nerve & external acoustic meatus Laterally- subcutaneous Medially –spine of sphenoid, sphenomandibular ligament,chorda tympanic nerve & middle meningeal artery Superior- middle cranial fossa Inferior – maxillary artery & vein
- #49 Lymphatic vessels from anterior surface drain into
- #51 Superficial portion: Inferior 2/3rd of zygomatic arch Angle of mandible,lower border of lateral surface of ramus Middle portion: Origin: Inner aspect of zygomatic arch Lower portion of lateral surface of ramus Inferior portion Origin: Deeper aspect of zygomatic arch Insertion: Upper portion of mandibular ramus and coronoid process Action: Elevation. Superficial fibres - protrusion of mandible
- #52 masseteric branch of anterior division of mandibular nerve Blood supply: maxillary artery, a branch of external carotid artery.
- #53 First first fingers are placed on each zygomatic arch( anterior to TMJ) Then They are dropped down slightly to the portion of the masseter attached to the zygomatic arch. once palpated the deep masseter, then the fingers drop to inferior attachment of the body of the ramus.(superficial masseter)
- #55 Insertion:- medial aspect of coronoid process & anterior border of ramus of mandible Anterior fibres orient vertically. Most posterior fibres almost horizontally and intervening fibres with intermediate degrees of obliquity like a fan.
- #56 Arises from Chronic strain of temporalis muscle, pulling the tendon that attaches to mandible causes
- #57 superficial head :Tuberosity of maxilla& inserts into Angle of mandible deep head : medial surface of lateral pterygoid plate & inserts into angle
- #58 Medial pterygoid nerve: leaves mandibular nerve immediately when it comes out of foramen ovale
- #59 Palpation Intraorally ,to palpate the medial pterygoid muscle slide the index finger a little posterior to the insertion site of inferior alveolar nerve block, to where the muscle is felt & press laterally.
- #61 Superior portion:from the roof of temporal fossa(greater wing of sphenoid) Inferior portion: from the lateral surface of lateral pterygoid plate. Insertion- by a tendon into- neck of the mandible, ant part of capsule of tmj through capsule into the meniscus
- #62 During closure of mouth, backward gliding of anterior disc and mandibular condyle controlled by slow elongation of lateral pterygoid while masseter and temporalis restore jaw to occlusal position.
- #67 Superior fibres of massetr [protrusion] Posterior fibers of temporalis [retrusion] Sprahyoid:Geniohyoid, Mylohyoid & Digastric [depresion]
- #68 Distance between incisal edges of maxillary & mandibular teeth
- #70 Lateral jaw palpation: palpates the lateral poles of condyle with index finger or two fingers placed near tragus, the patient is asked to slowly open & close the mouth. Once position is verified medial force is applied to determine the pain Posterior jaw position: Palpate the posterior surface of condyle during opening & closing of mandible. condyle displaces the little finger when in full occlusion if pain present, then positive
- #72 0.3mm special tinfoil allows step-by-step checking of the “discus articularis”. One keeps adding additional layers of 0.3mm special tinfoil, making the blocking of the bite progressively greater, until the patient is no longer able to clench the contra-laterally placed test-foil.
- #74 Direction of force of temporalis muscle is predominantly superior. Therefore these muscles elevate condyles in a straight superior position. Masseter & medial pterygoid provide forces in superio anterior position & seat condyles superiorly & anteriorly against the slopes of articular eminence Fig 1& 2 together result in musculoskeletal stability of tmj.
- #80 Osteo: bony articular surfaces are affected. Poly :group of disorders in which articular surfaces are inflamed.