Temporomandibular joint /certified fixed orthodontic courses by Indian dental academy

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The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.

Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
0091-9248678078

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Temporomandibular joint /certified fixed orthodontic courses by Indian dental academy

  1. 1. TEMPOROMANDIBULAR JOINT INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com 1
  2. 2. Temporomandibular joint  Types of joints  Embryology  Functional anatomy  Muscles of mastication  Biomechanics of TMJ  Evolution www.indiandentalacademy.com 2
  3. 3. Types of joints Depending on the types of tissues involved 1. Fibrous joints 2. Cartilaginous joints 3. Synovial joints www.indiandentalacademy.com 3
  4. 4. Fibrous joints 1. Sutures 2. Gomphosis 3. syndesmosis www.indiandentalacademy.com 4
  5. 5. Cartilaginous joints 1. Primary 2. secondary www.indiandentalacademy.com 5
  6. 6. Synovial joints  Permits significant movement  Synovial cavity  Synovial membrane  Synovial fluid  hyaline cartilage  capsule www.indiandentalacademy.com 6
  7. 7. Synovial joints • • Uniaxial/biaxial /multiaxial Planar /ginglymoid /pivot/condyloid/saddle/ball and socket • Hiltons law • Muscles acting upon a joint have same nerve supply as joint www.indiandentalacademy.com 7
  8. 8. TMJ  GINGLYMOID  DIARTHROIDAL  SYNOVIAL  TRUE COMPOUND www.indiandentalacademy.com 8
  9. 9. TMJ OTHER SYNOVIAL JOINTS 2 BLASTEMA -Temporal -Condylar Cavity formation within a single blastema Fibrous cartilage at the articular surfaces Hyaline cartilage at the articular surfaces. Cartilage acts as growth Does not www.indiandentalacademy.com centre 9
  10. 10. Temporomandibular joint  Types of joints  Embryology  Functional anatomy  Muscles of mastication  Biomechanics of TMJ  Evolution www.indiandentalacademy.com 10
  11. 11. Embryology  Primary Jaw joint Homologous reptiles.  -maeckels cartilage functions as the primary joint.mouth opening begins  Persists till 4 months IUL 6 weeks iu.-Membranous bone forms lateral to meckels cartilage at-body and ramus www.indiandentalacademy.com 11
  12. 12. Embryology 10th week-the joint forms both malleo- incudal and Definite jaw joint move together in synchrony for 8 weeks in fetal life. The accessory mandibular condylar cartilage develops as 1st blastema..  Grows towards the later developing temporal blastema.  www.indiandentalacademy.com 12
  13. 13. Embryology  -Lateral pterygoid develops medial to future condyle and causes movement at through the primary meckelian joint.  Fossa  Interposed connective tissue becomes thinner.  Two clefts develop in the fibrous connective tissue forming two joint cavities. www.indiandentalacademy.com 13
  14. 14. Embryology  1st inferior compartment  2nd superior compartment.  Invading synovial membrane compartment.  Cavitation.  Early immobilization  Early functional activity www.indiandentalacademy.com 14
  15. 15. Embryology Formation of condylar + temporal blastema and ossification Clefting and formation of joint cavity www.indiandentalacademy.com 15
  16. 16. Embryology  Articular disc-biconcave.  Ventarally –lpm  Dorsally –the superior laminae,inferior laminae www.indiandentalacademy.com 16
  17. 17. Embryology Fossa – flat  Articular tubercle  Absent condyle,no fossa/tubercle  www.indiandentalacademy.com 17
  18. 18. Temporomandibular joint  Types of joints  Embryology  Functional anatomy  Muscles of mastication  Biomechanics of TMJ  Evolution www.indiandentalacademy.com 18
  19. 19. 3 components that make up the masticatory system 1. Maxillae 2. Mandible 3. Temporal bone www.indiandentalacademy.com 19
  20. 20. TMJ  GINGLYMOID  DIARTHROIDAL  SYNOVIAL  TRUE COMPOUND www.indiandentalacademy.com 20
  21. 21. FUCTIONAL ANATOMY  SQUAMOUS PART OF TEMPORAL BONE  ARTICULAR DISC  CONDYLE www.indiandentalacademy.com 21
  22. 22. FUCTIONAL ANATOMY condyle  Poles of condyle  Convex articulating surface  Articulating surface –ant and post www.indiandentalacademy.com 22
  23. 23. FUCTIONAL ANATOMY Temporal bone  Squamous part  Concave-Glenoid fossa  Squamotympanic fissure  Articular eminence  Roof - thin www.indiandentalacademy.com 23
  24. 24. ARTICULAR DISC SAGITTAL VIEW POSTERIOR BORDER INTERMEDIATE ZONE ANTERIOR BORDER ANTERIOR VIEW www.indiandentalacademy.com 24
  25. 25. ARTICULAR DISC  Devoid of blood vessels and nerve  Flexible and adaptable to functional demands www.indiandentalacademy.com 25
  26. 26. Attachments of the articular discRetrodiscal tissue Loose connective tissue  Rich blood and nerve supply  Bilaminar zone Superior retrodiscal lamina(elastic fibres) Inferior retrodiscal lamina(collagenous fibres) www.indiandentalacademy.com 26
  27. 27. Attachments of the articular disc - Temporal bone Retrodiscal tissue Capsular ligament + superior LPM condyle Medially + laterally attached to the capsule which divides www.indiandentalacademy.com 27 joint cavity
  28. 28. ARTICULAR DISC  Articulating surfaces are covered with fibrous tissue Upper joint cavity Lower joint cavity  Synovial lining /fluid www.indiandentalacademy.com 28
  29. 29. Functions of synovial fluid I. Nutrition II. Lubrication 1. 2. Boundary lubrication (moving joint) Weeping lubrication(compressive forces) • Minimizes friction www.indiandentalacademy.com 29
  30. 30. Ligaments of TMJ  1. 2. 3. 4. 5. Limit joint movement Collateral ligaments Capsular ligaments Temporomandibular ligaments Sphenomandibular ligaments Stylomandibular ligaments www.indiandentalacademy.com Functional ligaments Accessory ligaments 30
  31. 31. Collateral (discal) ligament 1. 2.      Medial discal Lateral discal Divide joint medio laterally Allows passive movement of the disc Permits anterior + posterior rotation of disc on condyle Blood vessels + nerves Proprioception www.indiandentalacademy.com 31
  32. 32. Capsular ligament  Surrounds the TMJ  Resists forces that separate the articulating surfaces  proprioception www.indiandentalacademy.com 32
  33. 33. Temporomandibular ligament 1. 2.   Outer oblique portion Inner horizontal portion Reinforces capsular ligament OOP- Prevents excessive dropping of condyle / limits extent of mouth opening www.indiandentalacademy.com IHP 33
  34. 34. Temporomandibular ligamentaction • Limits rotational opening • Seen only in humans – erect posture • Prevents damage to submandibular / retromandibular structures www.indiandentalacademy.com 34
  35. 35. Temporomandibular ligament  IHP Limits posterior movement of condyle and disc  Prevents damage to the retrodiscal tissue www.indiandentalacademy.com 35
  36. 36. Sphenomandibular ligament  Extents from spine of sphenoid to lingula  No significant limiting effects on mandibe www.indiandentalacademy.com 36
  37. 37. Stylomandibular ligament  Extends from the styloid process to the angle + post border of ramus  Limits excessive protrusive movement www.indiandentalacademy.com 37
  38. 38. Temporomandibular joint  Types of joints  Embryology  Functional anatomy  Muscles of mastication  Biomechanics of TMJ  Evolution www.indiandentalacademy.com 38
  39. 39. Muscles of mastication  Masseter  Temporalis  Medial pterygoid  Lateral pterygoid  Digastric Muscles of mastication www.indiandentalacademy.com 39
  40. 40. The masseter Origin insertion & direction Function –elevation www.indiandentalacademy.com 40
  41. 41. The temporalis Function – Origin & insertion www.indiandentalacademy.com elevation retrusion 41
  42. 42. The medial pterygoid Function  Origin & insertion elevation Protrusion Muscle sling with Masseter www.indiandentalacademy.com U/l - mediotrusive 42
  43. 43. The lateral pterygoid- inferior portion Function-protrusion Origin & insertion U/l – mediotrusive www.indiandentalacademy.com 43 With depressors – downward+forward
  44. 44. The lateral pterygoid- superior portion Infratemporal surface Active during of greater wing of power stroke sphenoid – capsule Closure with ,disc ,neck www.indiandentalacademy.com elevators 44
  45. 45. The lateral pterygoids Exert medial pull on disc & condyle www.indiandentalacademy.com 45
  46. 46. The digastricus Function– b/L contraction depression of mandible with fixed hyoid bone Raises hyoid –swallowingwhen mandible is fixed www.indiandentalacademy.com 46
  47. 47. Other muscles coordinating Mandibular movements  Coordinated movements of Supahyoid  Infrahyoid  Posterior neck muscles www.indiandentalacademy.com 47
  48. 48. Summary of mandibular movements & muscles involved www.indiandentalacademy.com 48
  49. 49. Temporomandibular joint  Types of joints  Embryology  Functional anatomy  Muscles of mastication  Biomechanics of TMJ  Evolution www.indiandentalacademy.com 49
  50. 50. Biomechanics of TMJ   • Based on structure and function can be divided into 2 systems First joint system -Inferior joint cavity Second joint system -Superior joint cavity www.indiandentalacademy.com 50
  51. 51. Biomechanics of TMJ  Articular disc as meniscus 1. Not a determinant of joint movement Attached on one side and unattached on the other. Freely extends into the joint space 2. 3. www.indiandentalacademy.com 51
  52. 52. Biomechanics of TMJ  TMJ - no attachment  Yet stable due to muscles  Resting stage – tonus  Increase muscle activity - increase interarticular pressure  Absence of pressure - dislocate www.indiandentalacademy.com 52
  53. 53. Biomechanics of TMJ Disc space varies with pressure  Increased – disc space narrows  Decreased – space widens Condyle on anterior / posterior zone www.indiandentalacademy.com 53
  54. 54. Biomechanics of TMJ Mandibular opening and closing SRL –retract the disc  Closed joint position – relaxed  Stretched – during opening  www.indiandentalacademy.com 54
  55. 55. Biomechanics of TMJ Mandibular opening and closing SLP – protractor of the disc  ILP – protractor of condyle  So forward movement – articular cartilage – disc morphology.  opening closing www.indiandentalacademy.com 55
  56. 56.      Biomechanics of TMJ closed mouth resting position SLP - tonus SLP > SRL Resting position-interarticular pressure reduced,disc space wide. Disc rotated anteriorly Condyle contacts intermediate & post zone Open mouth –SRL stretches , SRL > SLP Disc rotated posteriorly www.indiandentalacademy.com 56
  57. 57. Biomechanics of TMJ www.indiandentalacademy.com 57
  58. 58. Biomechanics of TMJ Power stroke / chewing         pressure reduced on biting side Fulcrum around food Pressure increased on contralateral side Same side – separation – dislocation SLP - active ,positions disc anteriorly on condyle Stabilizes joint Teeth approach intercuspation –pressure increases Mechanical post rotation – intermediate zoneresting positionwww.indiandentalacademy.com 58
  59. 59. Biomechanics of TMJ  Points to remember 1. Ligaments do not actively participate in function of TMJ Ligaments do not stretch Articular surfaces must maintain constant contact 2. 3. www.indiandentalacademy.com 59
  60. 60. Temporomandibular joint  Types of joints  Embryology  Functional anatomy  Muscles of mastication  Biomechanics of TMJ  Evolution www.indiandentalacademy.com 60
  61. 61. Adaptive morphology is dependent upon Locomotion  Feeding www.indiandentalacademy.com 61
  62. 62. EVOLUTION OF T.M.J Primitive vertebrates  Collection of food led to dev of jaws along with fins Amphibians and reptiles  Greater demand on jaw mechanics to adjust to new habitat www.indiandentalacademy.com 62
  63. 63. Mammals  Greater benefit from food source  Modification in jaws, joint, dentition Humans  Upright posture  Bipedal locomotion  Shrinkage of human face www.indiandentalacademy.com 63
  64. 64. Earliest functional activity of TMJ 1.Prehension 2.Control size of mass of food entering alimentary tract -sharp cusps -force in a direction effective -sharp cutting edges www.indiandentalacademy.com 64
  65. 65. Jaw joint has been classified into1.Primitive jaw jointreptilian jointquadrate-articular occlusion jaw 2.Mamalian type of jaw jointdentary squamosal articulationearly TMJ www.indiandentalacademy.com 65
  66. 66. Primitive jaw joint –reptilian joint Maxillae  Palatoquadrate bar Mandible  Hyomandibular(stapes)  Quardate(incus)  Articulare(malleus)  Dentary Dentary –squamosal joint/mammalian jaw joint www.indiandentalacademy.com 66
  67. 67. Most primitive jaw  Flexible plate of fibrocartilage connects the upper and lower cartilagenous jaws(shark)  -1st arch no longer forms the gill and grows under the brain as palatoquadrate bar.It extends front to back under the base of the skull to join the lower jaw(maeckels cartilage )at the epiceratobranchial joint.  The second arch modified to support the first arch in its function-hyomandibular cartilage. www.indiandentalacademy.com 67
  68. 68. Relationship of primitive jaw and cranial base AMPHISTYLIC SUSPENSION Upper jaw connected to cranium-2 places Behind eye Hyomandibular cartilage attached to cranium www.indiandentalacademy.com 68
  69. 69. Relationship of primitive jaw and cranial base HYOSTYLIC SUSPENSION . Hyomandibular element was the only articulation between the jaws and the cranial base www.indiandentalacademy.com 69
  70. 70. Relationship of primitive jaw and cranial base Autostylic suspension Upper jaws are firmly fused to the cranial base.eg chimera www.indiandentalacademy.com 70
  71. 71. Relationship of primitive jaw and cranial base STREPTOSTYLIC SUSPENSION  Great degree of movement between jaws and cranial base  Assists in swallowing  Reptiles and modern snakes  The pterygopalatine component can remain clamped onto the animal while other parts shifted their grip www.indiandentalacademy.com 71
  72. 72. Mobility of upper and lower jaws Amphibians and higher vertibrates  Maxillary palatine , pterygoid elements attached to the cranium,but hyomandibular (stapes) ,quadrate (incus) and articulare (malleus) continued to form movable joint. www.indiandentalacademy.com 72
  73. 73. Bones dentine and enamel  Bones dentine and enamel first appeared in fossil records as-dermal plates of primitive creatures.  In primitive sharks the denticles extend into the jaws to give rise to teeth. The dermal bones sank into the skin . They gained attachment to muscles. www.indiandentalacademy.com 73
  74. 74. ` The bones at the margin of upper jaw  Pre maxillae-with ant teeth Maxillae – with marginal teeth Jugal bone-lower orbit Quadrato-jugal Quadrate  Squamosal bone    www.indiandentalacademy.com 74
  75. 75. Lower jaw Maeckels cartilage(core of the lower jaw)became invested in 8 separate dermal bony plates.       Dentary(with marginal row of teeth) 2 spenials Angular Surangular Prearticular 2 coronoid bones www.indiandentalacademy.com 75
  76. 76. Development of muscles Advanced reptiles – capitii mandibularis and pterygoid muscles.  Well divided muscles  Increased functional activity  Size of dentary bone,heterodont dentition  www.indiandentalacademy.com 76
  77. 77. Development of muscles  Alteration in orientation of jaw muscles  Forces directed away from the joint www.indiandentalacademy.com 77
  78. 78. Development of inter-articular disc  Primitive joint did not have any cartilage.  Lateral part of the muscle that extended from the pterygoid region to the maeckels cartilage gives rise to the cartilage. www.indiandentalacademy.com 78
  79. 79. Functional activity of the mamalian TMJ  Prehension  Tearing  Crushing www.indiandentalacademy.com 79
  80. 80. Prehension  Condyle clamped by glenoid processes  Reptiles have enlarged teeth at corners www.indiandentalacademy.com 80
  81. 81. Prehention 1. Speed -temporalis muscle 2. Constant reproduction of jaw closure -interlocking canines -hinge like tmj www.indiandentalacademy.com 81
  82. 82. Tearing  Combination of –muscles controlling the dentition and movement of the jaws –neck muscles  Carnivore dentition  Grazing activity of the ungulate www.indiandentalacademy.com 82
  83. 83. Crushing 1. 2. 3. Slicing (carnivores) Gnawing (rodent incisors) Grinding (herbivores) www.indiandentalacademy.com 83
  84. 84. Slicing in carnivore      Well dev canines Condyle encircled in fossa at level of occlusal surface of mandibular teeth Coronoid – large Disc present Right and left halves are not united at the symphysis. www.indiandentalacademy.com 84
  85. 85. Slicing in carnivore  Masseter +temporalis –well dev  Zygomatic arch-strong  No forward  Minimum lateral www.indiandentalacademy.com 85
  86. 86. Rodent - gnawing  Incisors chisel shaped  Continuous erruption  Differential wear  Ant –post oriented glenoid fossa  No side to side movement www.indiandentalacademy.com 86
  87. 87. Herbivore - grinding        Well dev molars Ascending ramus increased height Condyle oval No articular eminence Slight post glenoid process Capsule is present. Anisognathous-do not occlude simultaneously. www.indiandentalacademy.com 87
  88. 88. Herbivore - grinding  Disc & capsule present  Masseter + temporalis well dev but not as much as the carnivores.  Lat pterygoid  Lateral movements prominent www.indiandentalacademy.com 88
  89. 89. References  JEFFEREY P OKESON  GUNNAR E CARLSSON  RICHARD TEN CATE  GRAYS ANATOMY www.indiandentalacademy.com 89
  90. 90. Thank you For more details please visit www.indiandentalacademy.com www.indiandentalacademy.com 90

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