TMJ Biomechanics and Function
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Questions and Answers

Which movement of the mandible is responsible for opening the mouth?

  • Protrusion
  • Depression (correct)
  • Retrusion
  • Elevation

    • During rotational movement of the mandible, what is the relationship between the mandibular condyle and the disc?

  • The disc moves in the direction of the rotating condyle (correct)
  • The condyle and disc rotate together
  • The condyle slides relative to the disc
  • The condyle and disc move in opposite directions

    • What is the primary function of elevation of the mandible?

  • To facilitate speech
  • To close the mouth
  • To open the mouth
  • To grind food during mastication (correct)

    • What is the effect of abnormal function in one TMJ on the other?

    <p>It interferes with the function of the other joint</p> Signup and view all the answers

    During lateral excursion, what is the movement of the condyle and disc?

    <p>They slide together within the fossa</p> Signup and view all the answers

    What is the direction of movement of the mandibular condyle and disc during protrusion?

    <p>Anteriorly and slightly downwards</p> Signup and view all the answers

    What occurs during the early phase of opening the mouth?

    <p>Primary rotation of the mandible</p> Signup and view all the answers

    What is the function of the articular disc in the TMJ?

    <p>To guide the movement of the mandible</p> Signup and view all the answers

    During left lateral excursion, what is the movement of the left condyle?

    <p>It forms a pivot point within the fossa</p> Signup and view all the answers

    What marks the transition from the early phase to the late phase of opening the mouth?

    <p>A gradual transition from primary rotation to primary translation</p> Signup and view all the answers

    What is the primary function of the articular disk of the TMJ?

    <p>To generate greater congruency</p> Signup and view all the answers

    What type of joint is the TMJ?

    <p>Synovial joint</p> Signup and view all the answers

    What is the main function of the lateral temporomandibular ligament?

    <p>To provide passive stability</p> Signup and view all the answers

    What is the anatomical structure that separates the TMJ into two synovial joint cavities?

    <p>Articular disk</p> Signup and view all the answers

    What is the movement that involves the anterior movement of the mandible without significant rotation?

    <p>Protrusion</p> Signup and view all the answers

    What is the function of the retrodiscal tissue in the TMJ?

    <p>To provide passive stability</p> Signup and view all the answers

    What is the shape of the mandibular condyle?

    <p>Convex</p> Signup and view all the answers

    What is the function of the fibrous capsule in the TMJ?

    <p>To provide passive stability</p> Signup and view all the answers

    What is the function of the muscles in the TMJ?

    <p>To provide active stability</p> Signup and view all the answers

    What is the opposite movement of protrusion?

    <p>Retrusion</p> Signup and view all the answers

    During translation, what is the direction of the condyle and disc movement?

    <p>Forward and inferior</p> Signup and view all the answers

    What happens to the axis of rotation at the end of opening?

    <p>It shifts inferiorly</p> Signup and view all the answers

    What is the result of bilateral contraction of the masseter muscle?

    <p>It elevates the mandible to bring teeth into contact</p> Signup and view all the answers

    What is the result of unilateral contraction of the temporalis muscle?

    <p>It causes ipsilateral excursion</p> Signup and view all the answers

    What is the result of bilateral contraction of the medial pterygoid muscle?

    <p>It causes mandible elevation and slight protrusion</p> Signup and view all the answers

    What is the result of unilateral contraction of the medial pterygoid muscle?

    <p>It causes contralateral lateral excursion</p> Signup and view all the answers

    What is the function of the lateral pterygoid muscle?

    <p>Depression of the mandible</p> Signup and view all the answers

    What is the special role of the superior head of the lateral pterygoid?

    <p>Adjusting disc position</p> Signup and view all the answers

    What is the main function of the secondary muscles of mastication?

    <p>Depression of the mandible</p> Signup and view all the answers

    What is the result of bilateral contraction of the lateral pterygoid muscle?

    <p>Strong protrusion of the mandible</p> Signup and view all the answers

    Study Notes

    TMJ Biomechanics: Function

    • TMJ performs bilateral actions, including mastication, talking, and swallowing
    • The joint works with the tongue and teeth during the mastication process

    TMJ Biomechanics: Anatomy

    • The TMJ is a bicondylar synovial joint between the condyle in the lower jaw and the mandibular fossa of the temporal bone
    • The joint has a wide range of rotation and translation, with an articular disk cushioning the forces related to mastication
    • The disk separates the joint into two synovial joint cavities: the inferior joint cavity and the larger superior joint cavity

    Mandibular Condyle

    • The condyle has a convex shape with short medial and lateral poles
    • The medial pole is more prominent than the lateral pole
    • The condyle is covered by a thin layer of fibrocartilage

    Mandibular Fossa

    • The fossa is part of the temporal bone and forms the joint with the condyle

    Articular Disk of the TMJ

    • The disk is made of dense fibrocartilage
    • It lacks blood supply and sensory innervation
    • The disk's main function is to generate greater congruency and reduce contact pressure

    Stability of the TMJ

    • Passive stability is provided by the fibrous capsule, articular disk, lateral temporomandibular ligament, and retrodiscal tissue
    • Active stability is provided by muscles

    Osteokinematics of the TMJ

    • The TMJ has four movements: protrusion, retrusion, lateral excursion, and depression-elevation
    • Protrusion and retrusion involve anterior and posterior movements without significant rotation
    • Lateral excursion involves side-to-side movement of the mandible, guided by the mandibular fossa and articular disk
    • Depression and elevation involve opening and closing the mouth

    TMJ Arthrokinematics

    • The TMJ typically involves bilateral action
    • During rotational movement, the mandibular condyle rolls relative to the inferior surface of the disk
    • During translational movement, the mandibular condyle and disk slide together
    • The disk usually moves in the direction of the translating condyle

    Protrusion and Retrusion

    • Protrusion involves the mandibular condyle and disk translating anteriorly and slightly downwards
    • Retrusion involves the mandibular condyle and disk translating posteriorly and slightly upwards

    Lateral Excursion

    • Primary movement involves side-to-side translation of the condyle and disk within the fossa
    • Secondary movement involves slight rotational components

    Depression and Elevation

    • The early phase of opening the mouth involves primary rotation of the mandible relative to the temporal
    • The late phase involves a gradual transition from primary rotation to primary translation
    • At the end of opening, the axis of rotation shifts inferiorly

    Kinetics of the TMJ

    • The masseter muscle elevates the mandible and brings teeth into contact
    • The temporalis muscle elevates the mandible and slightly retrudes it
    • The medial pterygoid muscle elevates the mandible and protrudes it
    • The lateral pterygoid muscle depresses the mandible and protrudes it
    • The superior head of the lateral pterygoid adjusts disc position

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    Related Documents

    TMJ Biomechanics PDF

    Description

    This quiz covers the functions and mechanics of the Temporomandibular Joint (TMJ), including its role in mastication, talking, and swallowing. It also explores the anatomy and arthrology of the TMJ.

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