Muscles of mastication deepak final copy

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Muscles of mastication deepak final copy

  1. 1. MUSCLES OF MASTICATION PRESENTED BY: Dr.DEEPAk (1ST YEAR)
  2. 2. CONTENTS INTRODUCTION DEFINITIONS MUSCLES OF MASTICATION CLINICAL CONSIDERATIONS OF MUSCLES REFERENCES
  3. 3. MASTICATION : Rhythmic opposition and separation of jaws with the involvement of teeth ,lips ,cheeks and tongue for chewing of food in order to prepare it for swallowing and digestion. Main purpose of mastication is to reduce the size of food particles to a size that is convenient for swallowing (bolus formation) with the help of saliva.
  4. 4. DEVEOPMENT OF MUSCLES OF MASTICATION The muscular system develops from intra embryonic mesoderm from embryonic cells called myoblast. Muscles of mastication are derived from first or mandibular arch (first arch).
  5. 5. LATERAL VIEW OF A FOUR WEEK EMBRYO SHOWINGMUSCLES DERIVED FROM BRANCHIAL ARCHES
  6. 6. MUSCLES OF MASTICATION
  7. 7. PRIMARY MUSCLES OF MASTICATION Masseter Temporalis Lateral pterygoid Medial pterigoid SECONDARY MUSCLES OF MASTICATION The suprahyoid group of muscles being used as secondary or supplementary muscles they are Digastric Mylohyoid Geniohyoid
  8. 8. MASSETER  Quadrilateral and consist of three layers. ATTACHMENTS  Superficial Layer: :  Origin- thick aponeurosis. From zygomatic process of maxilla and anterior 2/3 of lower border of zygomatic arch,pass downward and back wards at an angle of 45degree.  Insertion - into lower part of lateral surface of ramus of mandible
  9. 9.  MIDDLE LAYER Origin -anterior 2/3 of the deep surface and posterior 1/3 of the lower border of the zygomatic arch, Insertion - middle part of ramus. DEEP LAYER: Origin -deep surface of the zygomatic arch, Insertion - upper part of the ramus and into the coronoid process.
  10. 10. RELATIONS OF MASSETERSUPERFICIAL Platysma Risorius Zygomaticus major Parotid gland Parotid duct Branches of facial nerve
  11. 11. DEEP SURFACE Overlies the, Insertion of temporalis and ramus of the mandible. In front buccinator and the buccal nerve. Massetric nerve and artery.
  12. 12. ANTERIOR Margin projects over thebuccinator and is crossedbelow by the facial vein.POSTERIOR Margin is overlapped bythe parotid gland.
  13. 13. Nerve supply: Massetric nerve, branch of anterior division of mandibular nerve.Blood supply: Maxillary artery, which is a branch of external carotid artery.
  14. 14. ACTIONS OF MASSETERActions: Elevates the mandible to close the mouth and to occlude the teeth in mastication. Its activity in the resting position is minimal. It has a small effect in side-to- side movement, protraction and retraction.
  15. 15. TEMPORALIS MUSCLETEMPORAL FASCIAE Fan shaped Thick aponeurotic sheet that roofs over the temporal fossa and covers the temporalis muscle..
  16. 16. ATTACHEMENTS Origin- whole of temporal fossa and deep surface of temporal fascia Fibers converge and descend into a tendon . It passes through the gap between the zygomatic arch and the side of the skull Insertion - Medial surface,apex,anterior and posterior border of coronoid process and anterior border of the ramus of the mandible as far as last molar
  17. 17. RELATIONS OF TEMPORALISSUPERFICIAL Skin Auricularis anterior Temporal fascia Superficial temporal vessels Auriculotemporal nerve Temporal branch of facial nerve Zygomatic arch masseter
  18. 18. DEEP SURFACE Temporal fossa Lateral pterygoid Superficial head of medial pterygoid Small part of buccinator Maxillary artery Deep temporal nerves Buccal vessels and nerveANTERIOR BORDER is seperated from the zygomatic bone by a mass of fat.
  19. 19. BLOOD SUPPLY Deep temporal part of maxillary arteryNERVE SUPPLY deep temporal branches of the anterior trunk of mandibular nerve.
  20. 20. ACTIONS OF TEMPORALIS Elevates the mandible, this movement requires both the upward pull of anterior fibers and backward pull of the posterior fibers. Posterior fibers draw the mandible backwards after it has been protruded. It is also a contributory to side to side grinding movement.
  21. 21. SIDE TO SIDE GRINDING MOVEMENT
  22. 22. LATERAL PTERYGOID ATTACHMENTS It is a short thick muscle with two parts or head UPPER head arise from infratemporal surface and infratemporal crest of greater wing of sphenoid bone LOWER head arise from lateral surface of lateral pterygoid plate. Its fibers pass backwards and laterally to be inserted into a depression (pterygoid fovea)on the front of the neck of the mandible and into the articular capsule and disc of the temporomandibular articulation.
  23. 23. BLOOD SUPPLYPterygoid branch of2nd part of maxillaryarteryNERVE SUPPLYNerve to lateralpterigoid branchanterior division oftrigiminal nerve
  24. 24. ACTIONS OF LATERAL PTERYGOID Assists in opening the mouth with suprahyoid muscles. Right lateral pterygoid and right medial pterygoid turns the chin to left side as a part of grinding movement.
  25. 25.  When the medial and lateral pterygoids of two sides act together they protrude the mandible so that the lower incisors project in front of the other. The upper (superior) head being involved in chewing
  26. 26. The combinded efforts of the Digastrics and LateralPterygoids provide for natural jaw opening.
  27. 27. SIDE TO SIDE GRINDING MOVEMENT
  28. 28. Medial and lateral pterygoid act together toprotrude the mandible
  29. 29. MEDIAL PTERYGOIDIt is a thick quadrilateral muscleATTACHEMENTS Origin – Superficial head (small): from the lateral surface of pyramidal process of the palatine bone and tuberosity of maxilla Deep head (large): medial surface of lateral pterygoid plate and adjoining process of the palatine bone. Its fibers pass downwards laterally and backwards Insertion -by a strong tendinous lamina ,to the postero-inferior part of the medial surfaces of the ramus and the angle of the mandible It is attached as high as mandibular foramen and as far forward as the mylohyoid groove
  30. 30. RELATIONS OF MEDIALPTERYGOIDRELATIONS lateral pterygoid lateral pterygoid plate lingual nerve inferior alveolar nerve Ramus of mandible maxillary artery sphenomandibular ligament.
  31. 31. NERVE SUPPLY Branch of the main trunk of the mandibular nerve.BLOOD SUPPLY Pterygoid branch of 2nd part of maxillary artery
  32. 32.  SECONDARY MUSCLES TAKING PART IN THE MASTICATION
  33. 33. The 4 primary muscles of mastication are in turn supported or supplemented by few secondary muscles known as SUPRAHYOID GROUP of muscles they are DIGASTRIC MYLOHYOID GENIOHYOID
  34. 34. DIAGASTRIC MUSCLE Two bellies united by tendon Origin – Anterior belly from diagastric fossa of mandible. Posterior belly from mastoid notch of temporal bone. Insertion –Both meet at the intermediate tendon and held by the fibrous pulley. The muscle has secondary role in mastication as a depressor muscle adding to the action of lateral pterygoid muscle when mouth is to be opened against resistance. Elevation of hyoid bone
  35. 35. MYLOHYOID MUSLE Flat triangular Origin –Mylohyoid line of mandible. Insertion – Middle and Anterior fibers into median raphae. Posterior fibers body of hyoid bone. The secondary role of this muscle is evident as a depressor seen in action when mouth is to be opened against resistance. It elevates the floor of mouth to help in deglutition.
  36. 36. GENIOHYOID Short and narrow musle lies above mylohyoid Origin –Inferior mental spine Insertion – Anterior surface of body of hyoid bone. Geniohyoid elevates the hyoid bone and draws it forward, thus acting as a partial antagonist to stylohyoid. When the hyoid bone is fixed, it depresses the mandible
  37. 37. GENIOHYOID MUSCLE
  38. 38. IMPORTANT FACTS ABOUT MASTICATION There are about 15 chews in a series from the time of food entry until swallowing Average jaw opening during chewing is between 16-20mm Average lateral displacement on chewing is between 3 and 5mm Duration of masticatory cycle varies between 0.6and 1 sec Men chew faster and have a shorter occlusal phase than women, it also depends on the type of food
  39. 39.  Masticatory forces: The aver maximum sustainable biting force is 756N{170 pounds}. Molar region: Biting force range 400-890N Premolar region: Biting force range 222-445N Cuspid region: Biting force range 133-334N Incisor region: Biting force range 89-111N {20-55 pounds}
  40. 40.  CLINICAL CONSIDERATIONS
  41. 41. CLASSIFICATION OF DISEASES OF MUSCLEI PRIMARY MYOPATHIES Dystrophies Myotonias Hypotonias Myasthenias Myositis Metabolic defects Miscellaneous(amyloplasias,contractures,degeneration)
  42. 42. II.SECONDARY MYOPATHIESa)Atrophy 1)Denervation 2)Disuse and fixation 3)Ageing and cachexiab) Hypertrophy 1) Developmental 2) Functionalc) Endocrined) Internal environment 1)Chemical 2)Vasculare)Infection1.Specific(toxoplasma,coxsackie virus, tetanus)2.General(rikettsial,typhoid,pneumococcal pneumonia)3.Post infection asthenia.
  43. 43. Muscle hypertrophy atrophy and hyperplasia  HYPERTROPHY: when total mass of muscle enlarges., increase in actin and myosin filament in response to maximal force causing enlargement of muscle fiber.  HYPERPLASIA: Under rare condition of extreme muscle force generation actual number of muscle fiber have been observed to increase.  ATROPHY: When total mass of muscle decreases.
  44. 44. MYASTHENIA GRAVIS Acquired autoimmune disorder of neuromuscular transmission characterized by muscle weaknessETIOLOGY Antibodies to acetylcholine receptor on skeletal muscle fiberCLINICAL FEATURES Diplopia, ptosis, drooping of the face, And a very sorrowful appearance to the patient. Patient rapidly exhausted, lose weight, death frequently occurs from respiratory failure.
  45. 45. TREATMENT AND PROGNOSIS Physostigmine administered intramuscularly improves the strength of the affected muscle in a matter of minutes No cure is known even though the prognosis is good in the relapsing type.
  46. 46. TETANUS(LOCK JAW)  Caused by exotoxins of gram positive bacillus Clostridium tetani.  Disease of the nervous system characterized by intense activity of motor neuron and resulting in severe muscle spasm CLINICAL FEATURES  Pain and stiffness in the jaws and neck muscles ,with muscle rigidity producing trismus and dysphagia  Risus sardonicus  Opisthotonous
  47. 47. TREATMENT All patients should receive antimicrobial drugs Active and passive immunization. Surgical wound care Anticonvulsant if indicated
  48. 48. BRUXISMBruxism : Jaw clenching, with or without forcible excursive movements, where the intensity of the clenching dictates the severity (or lack of) grinding .Clenching- It can occur as a brief rhythmic strong contractions of the jaw muscles during eccentric lateral jaw movements, or in maximum intercuspation,Causes 1) Associated with stressful events 2)Non stress related or hereditary
  49. 49.  Bruxism may lead to -tooth wear -fracture of the teeth or restoratrion -uncosmetic muscle hypertrophy Treatment -coronoplasty -maxillary stabalization appliance
  50. 50. MYOFACIAL PAIN DYSFUNCTIONSYNDROME Pain Muscle tenderness Clicking in the joint Limitation in the mouth openingTREATMENT Reassurane Physiotherapy and Myotherapeutic exercises TENS (Transcutaneous Electronic Nerve Stimulation) Muscle relaxants surgery
  51. 51.  Trismus during the administration of inferior alveolar nerve block Irritation to the medial pterigoid muscle Musle pain occure due to space infection like pterygomandibular space infection.
  52. 52. REFERENCES Kieth L. Moore, The developing human ,fourth edition 1992 Peter.L.Williams,Roger Worwik Grays Anatomy ,thirty six edition 1980 B.D.Chaurasias, Human anatomy,third edition 2000 Keith L.Moore,Clinically Oriented Anatomy fourth edition 1992 Anne M.R Agur,Grants atlas of anatomy 10 edition 1991 R.M.H Mc Minn,.R.T.Hutchings ,third edition1994 Arthur C Guyton,John E Hall,Textbook of Medical Physiology 10 edition 2000 William f ganong,Review of Medical Physiology,eighteen edition 1997
  53. 53.  Shafer,Hine,Textbook of oral pathology,fourth edition 1997 George A.Zarb,Charles L Bolender,Prosthodontic Treatment for Edentulous Patients, twelth edition 2004 Peter E Dawson,Evaluatio Diagnosis and Treatment of Occlusal Problems ,second edition1989 Fermin A Carranza,Micheal G Newman,Clinical Periodontology eight edition1996
  54. 54. Thank You

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