Functional neuroanatomy and physiology of masticatory system


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Functional neuroanatomy and physiology of masticatory system

  1. 1. Functional neuroanatomy andphysiology of masticatory system Preeti Kalia 3rd year PG student Department of Prosthodontics AECS Maaruti College of Dental Sciences
  2. 2.  “You cannot successfully treat dysfunction unless you understand function”
  3. 3. Functional neuroanatomy and physiology of masticatory system Neuromuscular systemMuscle Nerve Neuromusc ular function Pain
  4. 4. Neuromuscular systemNeurological Muscles structure
  5. 5. Muscles
  6. 6. Muscle function Isotonic contraction Isometric contraction Relaxation
  7. 7. Muscle function
  8. 8. Muscle function Eccentric contraction
  9. 9. Neurological structure
  10. 10. Types of neurons Afferent neurons Efferent neurons
  11. 11. Reticular formation
  12. 12. Thalamus
  13. 13. Hypothalamus
  14. 14. Limbic structure
  15. 15. Cerebral cortex
  16. 16. Sensory receptors  Nociceptors  Propriceptors  Muscle spindle  Golgi organ  Pacinian corpuscle
  17. 17. Muscle spindles
  18. 18. Golgi tendon receptor
  19. 19. Pacinian corpuscles
  20. 20. Nociceptors
  21. 21. Neuromuscular functionReflex action:It is response resulting from a stimulus that passes as an impulse along afferent neurons to a posterior nerve root or its cranial equivalent
  22. 22.  Monosynaptic reflex Polysynaptic reflex
  23. 23. Myotatic reflex
  24. 24. Nociceptive reflex It is a polysynaptic reflex Seen when hard food substances are taken in the mouth
  25. 25. Reciprocal innervation The controlling mechanism of antagonistic group of muscles
  26. 26. Regulation of muscle activity Gamma charge keeps the alpha motor neuron reflex prepared to receive impulses Influence of higher centers
  27. 27. Major function of masticatory system MasticationSwallowing Speech
  28. 28. Mastication Defined as act of chewing food
  29. 29. Chewing cycle
  30. 30. Mascles activity
  31. 31. Opening Start from static intercuspal position muscle activity begins in the ipsilateral inferior head of the lateral pterygoid muscle approximately half way through the period of tooth contact. Follow closely by the action of the contralateral inferior lateral pterygoid muscles. Both superior and inferior head of th lateral pterygoid muscle are active during the opening phase.
  32. 32. Opening Early in the opening phase, digastric muscles become active and remain until maximum opening position During the opening phase, masseter, temporalis, medial pterygoid, and superior head of lateral pterygoid muscles are inactive.
  33. 33. Closing initiation of jaw closing the inferior heads of the lateral pterygoid muscle ceases their functioning and activity initiated in the contralateral medial pterygoid muscle
  34. 34. Closing Contralateral medial pterygoid controls the upward and lateral positions of the mandible Activity increases in the anterior and posterior temporalis muscle, in the deep and superficial masseter muscles, and in the ipsilateral medial pterygoid muscle anterior and posterior temporalis muscle, in the deep and superficial masseter muscles, and in the ipsilateral medial pterygoid muscle activity declines in activity at the onset of intercuspation. There appears to be reciprocal action between the inferior head of the lateral pterygoid muscle and the medial pterygoid muscle in same subject
  35. 35. Tooth contact during mastication Gliding contacts Single contact Average time for tooth contact is 194 minutes 60% Gliding contacts seen during grinding 56% gliding contacts seen during opening
  36. 36. Forces of mastication Maximum biting force in females 70 to 99 pounds Males 118 to 142 pounds Maximum bite force for molar 91 to 198 pounds Central incisors 29 to 51 pounds
  37. 37. Swallowing Series of coordinated muscle movements that moves bolus from oral cavity through esophagus to stomach
  38. 38.  Somatic swallow Visceral swallow
  39. 39. Stages
  40. 40. Frequency of swallowing 590 times in 24 hours 146 cycles during eating 394 in between meals 50 cycles during sleep
  41. 41. Speech Important sounds formed by the lip are m,band p Teeth are important in saying s Tongue and palate are essential in forming d Tongue touches maxillary incisors to form th Lower lip touches maxillary incisors to form f and v
  42. 42. Pain Unpleasant sensation perceived in the cortex as a result of incoming nociceptive input.
  43. 43. Modulation of pain Non painful cutaneous nerve stimulation Intermittent painful stimulation Psychological modulation
  44. 44. Types of pain Central pain Projected pain Referred pain
  45. 45. Central excitatory effect Explains the mechanism of referred pain
  46. 46.  “Pain is inevitable. Suffering is optional.
  47. 47. References Okeson.J.P, Temporomandibular disorders and occlusion,6th edition , 2008, Mosby publication, St Louis, United States of America, pp:25-57