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 part 1 INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  2. 2. Temporomandibular joint  Evolution  Embryology  Functional anatomy and histology  Muscles of mastication  Biomechanics of TMJ www.indiandentalacademy.com
  3. 3. EVOLUTION OF TMJ  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
  4. 4. EVOLUTION OF TMJ  increasing efficiency of the feeding mechanism- critical factor in vertebrate evolution  Earliest functional activity of TMJ prehension Control size of mass of food entering alimentary tract www.indiandentalacademy.com
  5. 5. EVOLUTION OF TMJ  Mammals  Greater benefit from food source  Modification in jaws, joint, dentition  Humans  Upright posture / bipedal locomotion  Food collection shifted to jaws. www.indiandentalacademy.com
  6. 6. EVOLUTION OF TMJ  Primitive jaw joint – reptilian joint 1. Dentary 2. Quardate(incus) 3. Articulare(malleus)  Dentary – squamosal joint/mammalian jaw joint www.indiandentalacademy.com
  7. 7. EVOLUTION OF TMJ  Relationship of primitive jaw and cranial base  AMPHISTYLIC SUSPENSION  upper jaw connected to cranium Behind eye Hyomandibular cartilage attached to cranium  HYOSTYLIC SUSPENSION  Only lower jaw connected to cranium www.indiandentalacademy.com
  8. 8. EVOLUTION OF TMJ  STREPTOSTYLIC SUSPENSION  Great degree of movement between upper and lower jaw  Assists in swallowing  Amphibians and reptiles  Maxillary , pterygoid elements attached to the cranium www.indiandentalacademy.com
  9. 9. EVOLUTION OF TMJ development of muscles  Advanced reptiles – capitii mandibularis  Increased functional activity  Size of dentary bone,heterodont dentition  Forces directed away from the joint  Alteration in orientation of jaw muscles www.indiandentalacademy.com
  10. 10. EVOLUTION OF TMJ Mammal like reptiles - Prehension  Condyle clamped by glenoid processes www.indiandentalacademy.com
  11. 11. EVOLUTION OF TMJ Carnivore - cutting  Well dev canines  Coronoid – large  Condyle encircled in fossa  Disc present  Masseter +temporalis –well dev  No forward  Minimum lateral www.indiandentalacademy.com
  12. 12. EVOLUTION OF TMJ Rodent - gnawing  Incisors chisel shaped  Ant –post oriented glenoid fossa  Forward +upward movement  Well dev Masseter www.indiandentalacademy.com
  13. 13. EVOLUTION OF TMJ Herbivore - grinding  Well dev molars  Ascending ramus increased height  Condyle oval  No articular eminence  Post glenoid process  Disc & capsule present  Masseter + temporalis well dev  Lat pterygoid  Lateral movements prominent www.indiandentalacademy.com
  14. 14. Types of joints  Depending on the types of tissues involved  Fibrous joints  Cartilaginous joints  Synovial joints www.indiandentalacademy.com
  15. 15. Fibrous joints 1. Sutures 2. Gomphosis 3. syndesmosis www.indiandentalacademy.com
  16. 16. Cartilaginous joints  Primary  secondary www.indiandentalacademy.com
  17. 17. Synovial joints  Permits significant movement  Synovial cavity  Synovial membrane  Synovial fluid  hyaline cartilage  capsule www.indiandentalacademy.com
  18. 18. 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
  19. 19. TMJ  GINGLYMO  DIARTHROIDAL  SYNOVIAL  TRUE COMPOUND www.indiandentalacademy.com
  20. 20. embryology  Primary Jaw joint  Between Incus and Malleus  Persists till 4 months IUL www.indiandentalacademy.com
  21. 21. embryology  Secondary jaw joint  Between the condyle and temporal bone  Differs from other synovial joints www.indiandentalacademy.com
  22. 22. embryology Formation of condylar + temporal blastema and ossification Clefting and formation of joint cavity www.indiandentalacademy.com
  23. 23. Embryology TMJ - neonate  Lax  Stability –capsule  Fossa – flat  Articular tubercle  absent condyle,no fossa/tubercle www.indiandentalacademy.com
  24. 24. FUCTIONAL ANATOMY  SQUAMOUS PART OF TEMPORAL BONE  ARTICULAR DISC  CONDYLE www.indiandentalacademy.com
  25. 25. FUCTIONAL ANATOMY condyle  Poles of condyle  Convex articulating surface  Post articulating surface greater www.indiandentalacademy.com
  26. 26. FUCTIONAL ANATOMY temporal bone  Squamous part  Concave-Glenoid fossa  Articular eminence  Roof - thin www.indiandentalacademy.com
  27. 27. ARTICULAR DISC SAGITTAL VIEW POSTERIOR BORDER INTERMEDIATE ZONE ANTERIOR BORDER ANTERIOR VIEW www.indiandentalacademy.com
  28. 28. ARTICULAR DISC  Articulating surfaces are covered with fibrous tissue Upper joint cavity Lower joint cavity  Synovial lining /fluid www.indiandentalacademy.com
  29. 29. ARTICULAR DISC  Devoid of blood vessels and nerve  Morphology maintained  Flexible and adaptable to functional demands www.indiandentalacademy.com
  30. 30. Functions of synovial fluid  Nutrition  Lubrication 1. 2. Boundary lubrication Weeping lubrication • Minimizes friction www.indiandentalacademy.com
  31. 31. Retrodiscal tissue  Loose connective tissue  Rich blood and nerve supply Superior retrodiscal lamina Inferior retrodiscal lamina  Bilaminar zone www.indiandentalacademy.com
  32. 32. ARTICULAR DISC attachments Temporal bone Retrodiscal tissue Capsular ligament + superior LPM condyle Medially + laterally attached to the capsule which divides joint cavity www.indiandentalacademy.com
  33. 33. Histology of TMJ cartilage associated with the joint www.indiandentalacademy.com
  34. 34. Ligaments of TMJ  Collateral ligaments  Capsular ligaments  Temporomandibular ligaments Functional ligaments  Sphenomandibular ligaments  stylomandibular ligaments Accessory ligaments www.indiandentalacademy.com
  35. 35. Collateral (discal) ligament      Medial discal Lateral discal Divide joint medio laterally allows passive movement Permits anterior + posterior rotation of disc on condyle  Blood vessels + nerves  proprioception www.indiandentalacademy.com
  36. 36. Capsular ligament  Surrounds the TMJ  Retains synovial fluid  Resists medial ,lateral inferior forces that separate the articulating surfaces  Nerves + proprioception www.indiandentalacademy.com
  37. 37. Temporomandibular ligament  Reinforces the lateral aspect of capsular ligament  Outer oblique portion  Inner horizontal portion  OOP- Prevents excessive dropping of condyle / limits extent of mouth opening www.indiandentalacademy.com IHP
  38. 38. Temporomandibular ligamentaction • Limits rotational opening • Seen only in humans – erect posture • Prevents damage to submandibular / retromandibular structures www.indiandentalacademy.com
  39. 39. Temporomandibular ligament  IHP Limits posterior movement of condyle and disc  Prevents damage to the retrodiscal tissue www.indiandentalacademy.com
  40. 40. Sphenomandibular ligament  Extents from spine of sphenoid to lingula  No limiting effects on mandibe www.indiandentalacademy.com
  41. 41. Stylomandibular ligament  Extends from the styloid process to the angle + post border of ramus  Limits excessive protrusive movement www.indiandentalacademy.com
  42. 42. Muscles of mastication  Masseter  temporalis  Medial pterygoid  Lateral pterygoid  digastric www.indiandentalacademy.com
  43. 43. The masseter Origin & insertion Function –elevation U/ L- Mediotrusive www.indiandentalacademy.com
  44. 44. The temporalis Function – Origin & insertion www.indiandentalacademy.com elevation retrusion
  45. 45. The medial pterygoid  Origin & insertion Function - elevation Protrusion Muscle sling with Masseter U/l - mediotrusive www.indiandentalacademy.com
  46. 46. The lateral pterygoid- inferior portion Function-protrusion Origin & insertion U/l – mediotrusive With depressors – downward+forward www.indiandentalacademy.com
  47. 47. The lateral pterygoid- superior portion Infratemporal surface of greater wing of sphenoid – capsule ,disc ,neck Active during power stroke Closure with elevators www.indiandentalacademy.com
  48. 48. The lateral pterygoids Exert medial pull on disc & condyle www.indiandentalacademy.com
  49. 49. The digastricus Function– b/L contraction depression of mandible with fixed hyoid bone Raises hyoid -swallowing www.indiandentalacademy.com
  50. 50. Other muscles coordinating Mandibular movements www.indiandentalacademy.com
  51. 51. Summary of mandibular movements & muscles involved www.indiandentalacademy.com
  52. 52. Biomechanics of TMJ www.indiandentalacademy.c om
  53. 53. Biomechanics of TMJ   1. 2. 3. • 1. 2. 3. Based on structure and function can be divided into 2 systems ONE JOINT SYSTEM Condyle disc complex Inferior joint Tightly bound cavity Rotation SECOND JOINT SYSTEM Condyle disc with mandibular fossa Superior Not tightly bound joint cavity translation www.indiandentalacademy.com
  54. 54. Biomechanics of TMJ  Articular disc as meniscus 1. Freely extends into the joint space 2. does not divide the joint cavity 3. Not a determinant of joint movement www.indiandentalacademy.com
  55. 55. 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
  56. 56. Biomechanics of TMJ Disc space varies with pressure  Increased – disc space narrows Condyle on intermediate zone  Decreased – space widens Condyle on anterior / posterior zone www.indiandentalacademy.com
  57. 57. Biomechanics of TMJ Mandibular opening and closing  SRL –retract the disc  Closed joint position – relaxed  Stretched – during opening www.indiandentalacademy.com
  58. 58. Biomechanics of TMJ Mandibular opening and closing  SLP – protractor of the disc  Dual attachment  ILP – protractor of condyle  SLP –active during closure with elevators opening closing www.indiandentalacademy.com
  59. 59. 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
  60. 60. Biomechanics of TMJ www.indiandentalacademy.com
  61. 61. Biomechanics of TMJ Power stroke / chewing  Resistance met on closure –pressure reduced on biting side  Fulcrum around hard food  Pressure increased on contralateral side  Same side – separation – dislocation  SLP - active ,positions disc anteriorly on condyle  Stabilizes joint  Teeth approach intercuspation –pressure increases  Post rotation – intermediate zone-resting position www.indiandentalacademy.com
  62. 62. Biomechanics of TMJ  Points to remember 1. Ligaments do not actively participate in function of TMJ 2. Ligaments do not stretch 3. Articular surfaces must maintain constant contact www.indiandentalacademy.com
  63. 63. Thank you For more details please visit www.indiandentalacademy.com www.indiandentalacademy.com

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