TMJ Biomechanics and Functions
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Questions and Answers

What is the primary movement occurring during lateral excursion of the mandible?

  • Protrusion of the mandibular condyle and disc
  • Elevation of the mandible
  • Side to side translation of the condyle and disc within the fossa (correct)
  • Rotational movement of the condyle and disc

    • What occurs during the early phase of depression of the mandible?

  • The disc moves in the opposite direction of the condyle
  • The condyle rolls posteriorly within the concave inferior surface of the disc (correct)
  • The condyle rolls anteriorly within the concave inferior surface of the disc
  • The body of the mandible moves superiorly and posteriorly

    • What is the consequence of abnormal function in one TMJ?

  • It has no effect on the other TMJ
  • It leads to protrusion of the mandible
  • It naturally interferes with the function of the other TMJ (correct)
  • It causes the mandible to move only in a rotational manner

    • What occurs during retrusion of the mandible?

    <p>The mandibular condyle and disc translate posteriorly and slightly upwards</p> Signup and view all the answers

    What is the maximum amount of mouth opening that occurs during depression of the mandible?

    <p>During yawning or singing</p> Signup and view all the answers

    What is the movement of the mandible during the late phase of depression?

    <p>Primary translation of the mandible relative to the temporal</p> Signup and view all the answers

    What guides the movement of the mandible during lateral excursion?

    <p>The mandibular fossa and articular disc</p> Signup and view all the answers

    What is the action used to grind food during mastication?

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

    What is the result of bilateral action of the TMJs during movement of the mandible?

    <p>The movement of the mandible is coordinated and normal</p> Signup and view all the answers

    During which phase of depression does the body of the mandible move inferiorly and posteriorly?

    <p>Early phase</p> Signup and view all the answers

    What happens to the condyle and disc during translation?

    <p>They slide together in a forward and inferior direction.</p> Signup and view all the answers

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

    <p>The mandible is elevated and brought into contact with the maxilla.</p> Signup and view all the answers

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

    <p>Ipsilateral excursion of the mandible.</p> Signup and view all the answers

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

    <p>Mandible elevation and slight protrusion.</p> Signup and view all the answers

    What is the effect of unilateral contraction of the lateral pterygoid muscle?

    <p>Mandible depression.</p> Signup and view all the answers

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

    <p>Mandible depression.</p> Signup and view all the answers

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

    <p>Adjusting disc position.</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 temporalis muscle?

    <p>Mandible elevation and slight retrusion.</p> Signup and view all the answers

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

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

    What is the primary function of the TMJ?

    <p>To facilitate mastication, talking, and swallowing</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 function of the articular disk in the TMJ?

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

    What is the main component of the passive stability of the TMJ?

    <p>Fibrous capsule</p> Signup and view all the answers

    What is the movement of the mandible during protrusion?

    <p>Anterior movement without significant rotation</p> Signup and view all the answers

    What is the function of the medial pole of the mandibular condyle?

    <p>It is a prominent structure that provides a surface for articulation</p> Signup and view all the answers

    What is the characteristic of the articular disk of the TMJ?

    <p>It is a dense fibrocartilage that lacks blood supply and sensory innervation</p> Signup and view all the answers

    What is the function of the lateral temporomandibular ligament?

    <p>To provide stability to the joint during lateral movements</p> Signup and view all the answers

    What is the movement of the mandible during depression?

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

    What is the characteristic of the retrodiscal tissue?

    <p>It contains collagen and elastic tissue</p> Signup and view all the answers

    Study Notes

    TMJ Biomechanics

    • The TMJ (Temporomandibular Joint) is a bicondylar synovial joint between the condyle in the lower jaw and the mandibular fossa of the temporal bone.

    Function

    • The TMJ's main functions include mastication, talking, and swallowing, working in bilateral action with the tongue and teeth.

    Mastication Process

    • The mastication process involves the TMJ, tongue, and teeth working together to break down food.

    Arthrology of the TMJ

    • The TMJ is a synovial joint that permits a wide range of rotation and translation, with an articular disk cushioning the forces related to mastication.
    • The articular disk separates the joint into two synovial joint cavities: the inferior joint cavity and the superior joint cavity.

    Anatomy of the TMJ

    • The mandibular condyle has a convex shape with medial and lateral poles, covered by a thin layer of fibrocartilage.
    • The articular disk is made of dense fibrocartilage, lacks blood supply and sensory innervation, and helps to generate greater congruency within the TMJ.

    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 main movements: protrusion-retrusion, lateral excursion, depression-elevation.
    • Protrusion and retrusion involve anterior and posterior movements of the mandible 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, respectively.

    TMJ Arthrokinematics

    • The TMJ's arthrokinematics involve the movement of the mandible, with the articular disk translating in the direction of the condyle.
    • Protrusion and retrusion involve anterior and posterior translation of the condyle and disk, respectively.
    • Lateral excursion involves side-to-side translation of the condyle and disk.
    • Depression and elevation involve rotation and translation of the condyle and disk.

    Kinetics of the TMJ

    • The muscles responsible for TMJ movement include the masseter, temporalis, medial pterygoid, and lateral pterygoid.
    • Each muscle has a specific function in bilateral and unilateral contraction, affecting mandible movement and disc position.

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    TMJ Biomechanics PDF

    Description

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

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