Chapter 29 Temporomandibular Joint PDF

Chapter 29 Temporomandibular Joint Copyright © 2019 by Elsevier, Inc. All rights reserved.  Lesson 29.1 Function of the Temporomandibular Joint 1. To diagram and label a sagittal section of the temporomandibular joint (TMJ) 2. To define the role of a synovial cavity 3. To...

Chapter 29 Temporomandibular Joint Copyright © 2019 by Elsevier, Inc. All rights reserved.  Lesson 29.1 Function of the Temporomandibular Joint 1. To diagram and label a sagittal section of the temporomandibular joint (TMJ) 2. To define the role of a synovial cavity 3. To describe the two movements of the TMJ as the mouth opens and know where these movements take place 4. To describe the role of the superior posterior elastic lamina, the inferior posterior collagenous lamina, and the superior and inferior heads of the lateral pterygoid muscle as the jaw goes through its various functional movements Copyright © 2019 by Elsevier, Inc. All rights reserved. 2  Structure of the Temporomandibular Joint—Articulation  The articulation between the temporal bone and the mandible  The surface of one bone moves over the surface of the other.  Two joints that move and function as one  Bilateral joint because the mandible is fused at the midline  Articular disk is the small fibrous pad between bones of the TMJ.  Upper surface is concave and convex to match the contours of the mandibular fossa.  Thickest at posterior end (posterior band), thinnest in the middle (intermediate zone) Copyright © 2019 by Elsevier, Inc. All rights reserved. 3  Structure of the Temporomandibular Joint—Synovial Cavities  Synovial cavities located above and below articular disk  Epithelium lines these cavities and secretes synovial fluid.  Allows the surfaces to rub without irritation Copyright © 2019 by Elsevier, Inc. All rights reserved. 4 Structure of the Temporomandibular Joint—Diagram Copyright © 2019 by Elsevier, Inc. All rights reserved. 5  Structure of the Temporomandibular Joint—Fibrous Capsule  The TMJ is surrounded by a fibrous capsule.  Temporomandibular ligament thickens the lateral side.  Prevents the condyle from being displaced  Stylomandibular ligament and sphenomandibular ligament control movement on the medial side. Copyright © 2019 by Elsevier, Inc. All rights reserved. 6  Structure of the Temporomandibular Joint—Attachment of Articular Disk  Attached medially and laterally to the poles of the condyle  Attached anteriorly to fibers of the superior head of the lateral pterygoid muscle  Retrodiscal pad is posterior to the disk.  Blood supply from:  Ascending pharyngeal  Superficial temporal  Deep auricular  Anterior tympanic arteries  Nerve supply from:  Three branches of the trigeminal nerve Copyright © 2019 by Elsevier, Inc. All rights reserved. 7  Structure Copyright © 2019 by Elsevier, Inc. All rights reserved. 8  Movement  The TMJ has two types of movement  Rotational  Gliding Copyright © 2019 by Elsevier, Inc. All rights reserved. 9  Rotational Movement  As teeth begin to separate, there is a rotational movement in the lower synovial cavity between the disk and the condyle below.  Posterior elastic lamina pulls posteriorly on the disk so the disk and Condyle rotate on one another.  As the jaw opens farther the rotational movement continues.  Additional anterior gliding movement along the posterior slope of the articular eminence also occurs. Copyright © 2019 by Elsevier, Inc. All rights reserved. 10  Gliding Movement  Between the disk and the temporal bone  Condyle and disk move forward until slightly anterior to the crest of the articular eminence.  Superior head of lateral pterygoid controls the posterior movement of the disk.  Controls the release of contraction  Balances the posterior pull exerted by the elastic lamina  Lower posterior collagenous lamina prevents injury.  Keeps the elastic lamina and disk from being pulled too far forward Copyright © 2019 by Elsevier, Inc. All rights reserved. 11  Chewing  Mandible depressed by hyoid muscles  Lateral pterygoid pulls forward and down.  Mandible moves into lateral excursion to chewing side.  Condyle in position where condyle, disk, and temporal bone all in contact  Nonchewing side: condyle, disk, and temporal surfaces pulled slightly apart  Superior head of lateral pterygoid muscle contracts pulling the disk forward filling the space and stabilizing the joint. Copyright © 2019 by Elsevier, Inc. All rights reserved. 12  Chewing (Cont.)  Posterior fibers of temporalis muscle on nonchewing side contract, pull back on coronoid process  Pulls the condyle posteriorly  Occlusal surface of mandibular teeth grinds the food.  Upper head of lateral pterygoid muscle controls the posterior movement of the disk.  Smooth closing movement Copyright © 2019 by Elsevier, Inc. All rights reserved. 13  Lesson 29.2 Problems and Pain in the Temporomandibular Joint 5. To define disk derangement, subluxation, bruxism, and TMJ sounds 6. To discuss probably causes of TMJ pain Copyright © 2019 by Elsevier, Inc. All rights reserved. 14  Problems Associated with the TMJ—Pain  May be referred pain  Check radiograph  Palpate area  Pain often comes from muscle spasms, the ear, or malocclusion.  Four nerves, the V, VII, IX, and X, supply the sensory areas around the ear. Copyright © 2019 by Elsevier, Inc. All rights reserved. 15  Internal Problems of the TMJ— Sounds (Popping and Clicking)  Popping, clicking, or grinding without pain  Popping or clicking occurs when the disk is pulled too far forward when opening.  Posterior band gets caught between the head of the condyle and the articular eminence.  The band may pop forward or posteriorly, makes a reciprocal popping sound.  Possible that the sound will be too faint to hear, but can be felt on palpation  Frequently visible if only a problem on one side  Treatment includes ultrasonography. Physical therapy, and plastic splint. Copyright © 2019 by Elsevier, Inc. All rights reserved. 16  Internal Problems of the TMJ— Sounds (Grinding)  Grinding sound may come from  adhesions in synovial membranes of the joint.  arthritic changes.  perforations of the disk.  Treatment includes ultrasonography; may continue to recur. Copyright © 2019 by Elsevier, Inc. All rights reserved. 17  Internal Problems of the TMJ— Sounds (Disk Derangement)  Constant anterior displacement of the disk  permanent damage to the disk components  Posterior laminae may be torn  permanent anterior displacement  Can be medial or lateral attachments to the condyle poles  If torn, usually the lateral pole attachment  Requires surgery Copyright © 2019 by Elsevier, Inc. All rights reserved. 18  Internal Problems of the TMJ— Subluxation  When a person opens his or her mouth too wide and cannot close it or when closing causes popping  When the condyle glides too far forward and moves anterior to the articular eminence  Condyle cannot reposition in its proper place.  Possible causes:  Depth of condylar fossa and height of articular eminence  Position of capsule around the joint (controls the amount of contraction of the lateral pterygoid muscle)  Treatment is surgery to decrease the height of the articular eminence. Copyright © 2019 by Elsevier, Inc. All rights reserved. 19  Internal Problems of the TMJ— Bruxism  Tooth grinding  Usually during sleep  Creates tenderness in the TMJ area  Muscles of mastication become tired, but pain is felt in the joint.  Treatment: plastic night guard that covers the upper teeth  Eliminates wear on teeth and tenderness of teeth from stress on the periodontal ligament.  Other treatments involve use of tranquilizers to relieve tension. Copyright © 2019 by Elsevier, Inc. All rights reserved. 20  Internal Problems of the TMJ— Arthritis and Other Pain  Cortisone can relieve arthritis but pain remains a problem.  Some patients report a grinding sensation in the joint.  Might be the result of excessive wear on the disk  Occlusal surfaces wear away over time which leads to TMJ pain.  Rebuilding teeth to original height eases the pain  Most pain is actually not in the joint but in muscles. Copyright © 2019 by Elsevier, Inc. All rights reserved. 21