1.MUSCLES OF MASTICATION - Aditi Singh (P.G I year) Dept Of Pediatric & Preventive Dentistry Seema Dental College & Hospital,Rishikesh

2. CLASSIFICATIONHISTOLOGY GROSS ANATOMYEMBRYOLOGYINTRODUCTIONDISEASESAPPLIED ANATOMY 3. INTRODUCTION 4. Types of muscle tissue The basis of the classifications is as follows: DEPENDING UPON THE PRESENCE OR ABSENCE OF STRIATIONS. DEPENDING UPON THE CONTROL AND DEPENDING UPON THE FUNCTION. 5. DEPENDING UPON STRIATIONSSTRIATED MUSCLE Skeletal and cardiac musclesNON-STRIATED MUSCLE Smooth muscles. 6. DEPENDING UPON THE CONTROLVOLUNTARY MUSCLE Skeletal muscles.INVOLUNTARY MUSCLE Cardiac and smooth muscles 7. FUNCTIONAL CLASSIFICATION SKELETALMUSCLES SMOOTH MUSCLES CARDIAC MUSCLES 8. MUSCLES ATTACHMENTS Fleshy Attachments They have muscle cells ending close to the periosteum . Tendon Attachments They are tough, flexible, cable like concentrations of the collagen fibers 9. Aponeuroses and Septa They are flattened extensions of thin concentration. Raphae Interdigitation of tendinous ends. 10. Forms of Striated muscles also vary according to situation and function. 1. 2. 3. 4. 5. 6. 7.Strap like (Flat) Sternohyoid Fusiform (Bellied) Digastrics Fan shaped (Triangular) Temporalis Unipennate (Feather like) Bipennate Temporalis Multipennate Masseter Sphincter (Circular) Orbicularis oris 11. Differences in design depends on 1. Surface of bone available for muscle attachment. 2. Speed of contraction. 3. Range of movement. 4. Force of contraction. 12. Actions of muscles Muscles move parts only by pulling them. Musculoskeletal apparatus is designed in opposing system. Agonists: They act together to pull in a given direction. Antagonists: They pull in the opposite direction to bring parts back to the original position. 13. EMBRYOLOGY 14. The muscles of mastication develop from the mesenchyme of the mandibular arch. Muscle differentiation : 7th week Nerve Fibres : 8th week Fetal Histologic Structures : 22nd week 15. TEMPORALIS : 8TH WEEK ANTERIOR TO OTIC CAPSULE MASSETER : 8TH WEEK BEGINS ATTACHMENT TO ZYGOMATIC ARCH MEDIAL & LATERAL PTERYGOID : 7TH WEEK RELATED TO CARTILAGE OF CRANIAL BASE & CONDYLE 16. HISTOLOGY 17. 18.05.200423 18. .CLASSIFICATION OF MUSCLES OF MASTICATION 19. SUPRAMANDIBULAR OR ELEVATORS OF THE MANDIBLE Temporalis Masseter Medial pterygoid Lateral pterygoid 20. Inframandibular or Depressors of the mandible Digastrics Geniohyoid Stylohyoid Mylohyoid 21. Other muscles which help in mastication Buccinator Depressor anguli oris Levator anguli oris Levator labii superioris alaeque nasi Levator labii superioris Zygomaticus major Zygomaticus minor 22. SUPRAMANDIBULAR OR ELEVATORS OF MANDIBLE 23. MUSCLES OF MASTICATION 24. TEMPORALIS 25. MASSETER 26. LATERAL PTERYGOID 27. MEDIAL PTERYGOID 28. INFRAMANDIBULAR OR DEPRESSORS OF MANDIBLE 29. DISEASES OF THE MUSCLES 30. HYPOTONIA MYOTONIA HYPERTROPHY MUSCLE DYSTROPHIES MYASTHENIA 31. Myasthenia: Myasthenia constitutes a group of disease where there is basic disorder of muscle excitability and contractility and include 1. Myasthenia gravis. 2. Familial periodic paralysis 3. Aldosteronism Etiology: Etiology is defect in neuromuscular transmission. It appears that the fault is in acetylcholine mechanism, the motor end organ being normal. 32. Clinical features Rapidly developing weakness in voluntarily muscles. Difficulty in mastication Deglutition, and dropping of the jaws. Speech is slow and slurred. Disturbance in taste sensation occurs in some patients. 33. Diplopia and ptosis, along with the dropping of the face lend to the sorrowful appearance to the patient Death frequently occurs from respiratory failure. 34. Treatment and prognosis Drug of choice is physostigmine, an anti cholinesterase, No permanent cure for the disease is known. 35. APPLIED ANATOMY INFECTIONS OF SPECIFIC TISSUE SPACES Tissues spaces or facial spaces, are potential spaces situated between planes of fascia which form natural pathways along which infection may spread, producing a cellulitis, or within which infection become localized with actual abscess formation. 36. CELLULITIS VS ABSCESS 37. TRISMUS Trismus is limited opening of the joint. Causes: Odontogenic Acute infectionPericoronitis, Lugwids, Submasseteric space and Infra temporal space. Chronic infections- Tuberculous, osteomyelitis of ramus /body of mandible. 38. Trauma Inflammation Myositis Ossificans Tetany Tetanus Psychomatic disorders: Trismus Hystericus Inferior alveolar block given into medial ptergyoid muscle leads to formation of hematoma which in turn gets fibrosed leading to trismus 39. BRUXISM 40. BRUXISM Its the clenching or grinding of the teeth when the individual is not chewing or swallowing. T/t : Regulate (Control the habit) 41. MYOFACIAL PAIN DYSFUNCTION SYNDROME- MPDS MPDS is a pain disorder, in which unilateral pain is referred from the trigger points in myofacial structures, to the muscles of head and neck. Pain is constant, dull ache in contract to the sudden sharp, shooting, intermittent pain of neuralgias (chronic pain). 42. TREATMENT FOR MPDS REMOVE EXTRACT RESHAPE GRIND REPOSITION ORTHOGNATHIC SURGERY RESTORE- ENDODONTIC THERAPY REPLACE PROSTHESIS RECONSTRUCT- TMJ SURGERY REGULATE CONTROL HABIT AND SYMPTOMS 43. References Williams .P. et al Grays Anatomy -38th edition 1995. Chaurasia B.D. Head and Neck- II volume 4th edition. I B Singh , Human Embryology 6th edition Mc Minn, Lasts Anatomy 8th edition. Shafer et al, Text book of oral pathology- 5th edition. Malik .N, Text book of oral and maxillofacial surgery1st edition. Burkett, Text book of oral medicine- 4th edition William R Proffit , Henry Fields, David Sarver.Contemporary Orthodontics 4th ed