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Chapter 24

Chapter 24. The Temporomandibular Joint. Overview. The stomatognathic system comprises the temporomandibular joint (TMJ), the masticatory systems, and the related organs and tissues such as the salivary glands

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Chapter 24

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  1. Chapter 24 The Temporomandibular Joint

  2. Overview • The stomatognathic system comprises the temporomandibular joint (TMJ), the masticatory systems, and the related organs and tissues such as the salivary glands • Due to the proximity of this system with the other structures of the head and neck, an intimate relationship exists • This relationship begins in the early stages of human embryology

  3. ANATOMY

  4. Bones • Mandible • Maxilla • Zygomatic arch • Temporal bone

  5. Temporomandibular Joint • The articular surfaces of the temporomandibular joint are lined by fibrous tissue - this reflects the development of the joint • Unlike all other synovial joints whose articular surfaces develop endochondrally and are therefore lined by hyaline cartilage, the temporomandibular joint develops in membrane

  6. Intra-articular Disc • Fibrous in structure • Divides the joint cavity into two regions • Thinnest centrally • Attaches anteriorly to the lateral pterygoid • Attaches posteriorly to the condyle

  7. Joint Capsule • Capsular ligaments – fibers only pass between the temporal bone and mandible on the lateral side • Intrinsic ligaments – short fibers which pass from the bone to the intra-articular disc

  8. Ligamentous support • Lateral TMJ ligament • Stylomandibular ligament

  9. Muscles • Lateral pterygoid • Origin – • Upper head arises from the infratemporal surface of the greater wing of the sphenoid • Lower head arises from the lateral surface of the lateral pterygoid plate • Insertion - The anterior aspect of the neck of the mandibular condyle and capsule of the TMJ • Innervation - A branch of the mandibular division of the trigeminal nerve • Function • Upper head - involved mainly with chewing, and functions to anteriorly rotate the disc on the condyle during the closing movement • Lower head - exerts an anterior, lateral, and inferior pull on the mandible, thereby opening the jaw, protruding the mandible, and deviating the mandible to the opposite side

  10. Muscles • Medial pterygoid • Origin - Deep origin situated on the medial aspect of the mandibular ramus • Insertion - The inferior and posterior aspects of the medial subsurface of the ramus and angle of the mandible • Innervation - A branch of the mandibular division of the trigeminal nerve • Function - Working bilaterally - assists in mouth closing. Working unilaterally – deviation of the mandible toward the opposite side

  11. Muscles • Masseter - two-layered quadrilateral shaped muscle. • Origin • The superficial portion arises from the anterior two-thirds of the lower border of the zygomatic arch • The deep portion arises from the medial surface of the zygomatic arch. • Insertion - On the lateral surface of the coronoid process of the mandible, upper half of the ramus and angle of the mandible • Innervation - A branch of the mandibular division of the trigeminal nerve • Function - The major function of the masseter is to elevate the mandible, thereby occluding the teeth during mastication.

  12. Muscles • Tempororalis • Origin - The floor of the temporal fossa and temporal fascia • Insertion - On the anterior border of the coronoid process and anterior border of the ramus of the mandible • Innervation - A branch of the mandibular division of the trigeminal nerve • Function - assists with mouth closing/side-to-side grinding of the teeth. Also provides a good deal of stability to the joint

  13. Muscles • Digastric • Origin - The posterior belly arises from the mastoid, or digastric, notch immediately behind the mastoid process of the temporal bone. • Insertion - The posterior belly passes downwards and forwards towards the hyoid bone where it becomes the intermediate digastric tendon and joins with the anterior belly. • Nerve Supply - derived from the digastric branch of the facial nerve. • Vasculature - arterial blood supply from the posterior auricular and occipital arteries. • Action - The muscle depresses the mandible and can elevate the hyoid bone. The posterior bellies act in unison and are particularly active during swallowing and chewing.

  14. BIOMECHANICS

  15. Biomechanics • TMJ motions involve a combination of rolls and glides of the mandibular head and disc • All TMJ motions involve all or some of the following: • Anterior/posterior glide • Medial/lateral glide • Inferior/posterior glide

  16. Opening and closing • Mouth opening • Anterior glide • Lateral glide • Inferior glide • Mouth closing • Posterior glide • Medial glide • Superior glide

  17. Lateral Deviation • Contralateral deviation • Anterior, inferior and lateral glide of the mandibular head and disc • Ipsilateral deviation • Posterior, superior and medial glide of the mandibular head and disc

  18. Protrusion and Retrusion • Protrusion • Anterior, inferior and lateral glide of the mandibular head and disc • Retrusion • Posterior, superior and medial glide of the mandibular head and disc

  19. EXAMINATION

  20. Examination • As with any other synovial joint, there are a number of possible causes/scenarios: • Local cause • Referred cause • Loss of motion with or without pain • Excessive motion with or without pain

  21. History • There are three cardinal features of temporomandibular disorders (TMD): • Restricted jaw function (intermittent or progressive) • Joint noise (significant if associated with other factors) • Orofacial pain (Pain that is centered immediately in front of the tragus of the ear and projects to the ear, temple, cheek, and along the mandible is highly-diagnostic for TMD) • It is important to observe the patient’s mouth while they talk

  22. History • Attempt to determine a specific mechanism: • Trauma (including surgery – “controlled trauma”) • Posture • Emotional factors • Parafunctional habits (cheek biting, nail biting, pencil chewing, teeth clenching (day), bruxism (night)) • Symptom-provoking motions of the TMJ or neighboring joint(s)

  23. History • The patient’s past dental and orthodontic history • Whether the patient has experienced any “locking” of the jaw • Whether the symptoms are improving or worsening

  24. History • Systems review • Pain or dysfunction in the orofacial region can often be due to non-musculoskeletal causes: • Otolaryngologic disease • Neurologic disease • Vascular disease • Neoplastic, and infectious disease • Psychogenic disease

  25. Observation • The forward head posture is frequently associated with TMD…..try it • A lateral deviation of the jaw, evidenced by a malalignment or malocclusion of the upper and lower teeth, may cause an adaptive shortening of the mastication muscles on one side, and a lengthening of the mastication muscles on the contralateral side.

  26. Observation • Cavities, wear patterns, and restored and missing teeth should be noted • Tooth wear and fracture are often destructive signs of parafunctional habits • The rest position of the TMJ should be noted • The rest position of the TMJ is determined by gently placing the little finger with the palmar portion facing anteriorly into the external auditory meatus. From an open mouth position, the patient is asked to slowly close their mouth. At the point of the resting position, the patient’s mandibular heads should be felt to gently touch the finger.

  27. Range of Motion • The range of motion of the cervical spine, craniovertebral joints and the shoulders should be assessed • The range of motion of the neck and jaw should then be assessed: • Active range of motion with passive overpressure to assess the end feel.

  28. Range of Motion • All movements should be smooth and without noise or pain • If pain occurs, a determination should be made as to where in the range the pain occurs, and the location of the pain • The type and temporal sequence of joint clicking can provide the clinician with information

  29. Joint Noise • Reciprocal clicking is defined as clicking that occurs during opening and again during closing. • Early clicking usually indicates a small anterior displacement • Late clicking usually indicates that the disc has been further displaced • Often due to articular hypermobility, and is accompanied by a deviation of the jaw toward the contralateral side.

  30. Mouth Opening • Mouth opening is the most revealing and diagnostic movement for TMD • Normal motion tested using knuckle test (approximately a two-three-knuckle width of the non-dominant hand) or more objectively by measuring (closer to 40 mm) • A limited opening of the jaw may indicate joint hypomobility, muscle tightness, or the presence of trigger points within the elevator muscles: the temporalis, masseter and medial pterygoid • Other causes of diminished mandibular opening include structural disorders of the TMJ, such as ankylosis, internal derangements, and gross osteoarthritis

  31. C and S Curves • A ‘C-pattern’ of motion occurs if the hypomobility is due to internal derangement • The mandible deviates toward the involved side in the midrange of opening before returning to normal. • An ‘S-pattern’ of movement while opening the mouth may indicate a muscle imbalance. An arc may indicate a muscle imbalance • Lateral excursion of the mandible with mouth opening implicates contralateral structures such as the contralateral disc, masseter, temporalis, lateral pterygoid, or the lateral ligaments

  32. Palpation • Palpation of the TMJ is used to assess tenderness, skin temperature, muscle tone, swelling, skin moisture, and the location of trigger points • Palpations of the lateral and posterior aspects of the temporomandibular joints are performed bilaterally and simultaneously

  33. Strength Testing • It is important to be able to selectively stress the muscles of mastication and facial expression to determine whether they are implicated in the symptoms

  34. Ligament Stress Tests • The ligament stress tests assess the integrity of the capsule and ligaments • Positive findings include excessive motion as compared to the other side, or pain • Two structures are primarily tested: • Temporomandibular ligament • Joint capsule

  35. Passive Articular Mobility • The passive articular mobility tests assess the joint glides and the end feels • Findings are compared with each side • Pain or a restricted glide are positive findings and may indicate articular involvement or a capsular restriction. • It is important to check the specific glides that are related to the loss of active motion. For example, if a patient demonstrated diminished mouth opening mouth, the combined anterior, inferior, and lateral glide is assessed for each joint.

  36. Articular glides • Mouth opening, contralateral deviation, and protrusion all involve an anterior, inferior and lateral glide of the mandibular head and disc • Mouth closing, ipsilateral deviation, and retrusion all involve an posterior, superior and medial glide of the mandibular head and disc

  37. Conclusions • If the joint glides are normal – the joint is OK • Check ligaments and surrounding tissues • If the joint glides are restricted, the cause could indicate a joint/joint capsule restriction, a ligamentous adhesion or adaptive shortening of the surrounding tissues – need to mobilize the offending joint and re-assess • The intervention should always match the diagnosis!!

  38. Articular tests • Dynamic loading • The patient bites forcefully on a cotton roll or tongue depressor on one side. This maneuver loads the contralateral TMJ. • Joint compression • The clinician, standing behind the seated or supine patient, places the fingers of each hand under each side of the mandible, with the thumbs resting on the ramus. The mandible is then tipped posteriorly and inferiorly to compress the joint surfaces

  39. Neurological tests • Trigeminal sensation • Trigeminal reflex

  40. INTERVENTION

  41. Intervention • Based on: • Stage of healing. Chronic TMD pain often occurs because of secondary factors: • A fixed head forward posture • Abnormal stress levels • Depression • Oral parafunctional habits • Structure involved

  42. Acute Stage • The acute patient typically demonstrates: • A capsular pattern of restriction (decreased ipsilateral opening and lateral deviation to the contralateral side), with pain and tenderness on the same side • There may be associated ligamentous damage (positive stress tests), or muscular damage (positive strength tests)

  43. Acute Stage • The usual methods of decreasing inflammation are recommended: PRICEMEM • Protection • Rest • Ice • Compression • Elevation? • Manual therapy • Early motion • Medications

  44. TMJ Exercises • Acute stage: • “6x6” exercise protocol of Rocabado • Cork exercise • Tongue positioning during mouth opening and closing

  45. TMJ Exercises • Functional Stage: • Strengthening exercises for the cervicothoracic stabilizers, and the scapular stabilizers • Stretching exercises for the scalenes, trapezius, pectoralis minor, and levator scapulae; and the suboccipital extensors

  46. Home (Automobilization) Exercises • Mouth opening exercise • Tongue depressor exercise • Toothpick exercise • Distraction mobilization

  47. Functional (Chronic) Stage • Postural and patient education should form the cornerstone of any plan of care for TMD • Psychotherapy referral • Manual techniques • Exercise • Thermal and electrotherapeutic modalities • Trigger point therapy

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