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Mastication Muscle Disorders

Dr. Carolyn J. Agresti, MD - Otolaryngologist (ENT) Dr. Carolyn J. Agresti, MD - Otolaryngologist (ENT)
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Rx Musculoskeletal System (A - Z)

Mastication muscle disorders refer to a group of conditions that primarily affect the muscles responsible for chewing. These disorders can manifest as pain, weakness, stiffness, or abnormal movement of the jaw muscles, often leading to difficulty in biting, speaking, or swallowing. Although they are sometimes lumped together with temporomandibular joint disorders (TMD), mastication muscle disorders specifically involve the muscles—masseter, temporalis, medial pterygoid, and lateral pterygoid—and their associated tendons and fascia PMC.

Anatomy of the Muscles of Mastication

Structure & Location

The four primary muscles of mastication are:

  1. Masseter: A thick, rectangular muscle on the lateral side of the jaw.

  2. Temporalis: A fan-shaped muscle covering the temporal bone.

  3. Medial Pterygoid: Deep muscle on the medial aspect of the mandibular ramus.

  4. Lateral Pterygoid: Two-headed muscle in the infratemporal fossa, sitting above the medial pterygoid Wikipedia.

Origin & Insertion

  • Masseter:

    • Origin: Zygomatic arch.

    • Insertion: Lateral surface of the mandibular ramus and angle.

  • Temporalis:

    • Origin: Temporal fossa of the skull.

    • Insertion: Coronoid process and anterior ramus of the mandible.

  • Medial Pterygoid:

    • Origin: Medial surface of lateral pterygoid plate and palatine bone.

    • Insertion: Medial mandibular ramus below the mandibular foramen.

  • Lateral Pterygoid:

    • Origin: Superior head from the infratemporal surface of the greater wing of the sphenoid; inferior head from the lateral pterygoid plate.

    • Insertion: Condylar neck of mandible and articular disc of the temporomandibular joint Wikipedia.

Blood Supply

All four muscles receive arterial blood primarily from the maxillary artery, a terminal branch of the external carotid artery. The masseter also has contributions from the masseteric artery, while the pterygoids receive small branches from the pterygoid portion of the maxillary artery NCBI.

Nerve Supply

Unlike most facial muscles (innervated by CN VII), the muscles of mastication derive motor innervation from the mandibular branch (V₃) of the trigeminal nerve (CN V). This branch carries both sensory and motor fibers dedicated to jaw movement Wikipedia.

Functions

  1. Elevation of the Mandible: Closing the jaw for biting (masseter, temporalis, medial pterygoid).

  2. Depression of the Mandible: Opening the jaw (lateral pterygoid plays a role).

  3. Protrusion: Pushing the jaw forward (lateral and medial pterygoids).

  4. Retrusion: Pulling the jaw backward (posterior fibers of temporalis).

  5. Lateral Excursion: Side-to-side movement for grinding (contralateral pterygoids).

  6. Stabilization: Holding the jaw steady during speech and swallowing (deep masseter fibers) Wikipedia.

Types of Mastication Muscle Disorders

According to the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD), muscle-related jaw pain falls into four main subclasses:

  1. Myalgia (local, myofascial, and referred pain)

  2. Tendonitis

  3. Myositis (inflammation of muscle tissue)

  4. Spasm (sudden involuntary contraction) PMC

Additionally, TMD classification by cause includes:

  • Hyperactivity/Spasm/Trismus

  • Inflammation (Myositis)

  • Trauma

  • Myofascial Pain & Fibromyalgia

  • Atrophy/Hypertrophy Wikipedia

Causes

  1. Bruxism (Teeth Grinding): Excessive muscle use; leads to overwork and fatigue Harkins Pain & Sleep Management Group.

  2. Malocclusion: Misaligned bite increases muscle strain Wikipedia.

  3. Trauma to the Jaw: Direct injury causing inflammation or spasm.

  4. Poor Posture: Neck forward posture increases tension in mastication muscles.

  5. Stress & Anxiety: Emotional tension manifests as muscle clenching Frontiers in Oral Medicine.

  6. Arthritic Changes: Indirect muscle pain due to altered joint mechanics.

  7. Infection: Localized (e.g., abscess) or systemic (rheumatic fever).

  8. Tumors: Rare, benign or malignant growths affecting muscle integrity.

  9. Autoimmune Disorders: Myasthenia gravis causes muscle weakness.

  10. Metabolic Diseases: Fibromyalgia involves widespread muscle pain.

  11. Medication Side Effects: Statins can cause myalgia.

  12. Neuropathy: Trigeminal neuralgia spasms can involve masticatory muscles.

  13. Nutritional Deficiency: Low vitamin D or B₁₂ linked to muscle pain.

  14. Electrolyte Imbalance: Hypocalcemia or hypomagnesemia triggers cramps.

  15. Systemic Inflammation: Lupus or polymyositis affecting muscle tissue.

  16. Hormonal Fluctuations: Menstrual cycle can exacerbate pain perception.

  17. Parafunctional Habits: Chewing gum or pens excessively.

  18. Dental Procedures: Prolonged mouth opening during treatment.

  19. Cold Exposure: Vasoconstriction leads to muscle stiffness.

  20. Genetic Predisposition: Family history of TMD or chronic pain.

Symptoms

  1. Jaw Pain: Dull ache or sharp pain during movement Physiopedia.

  2. Muscle Tenderness: Pain on palpation of masseter or temporalis.

  3. Stiffness: Difficulty opening or closing the mouth fully.

  4. Limited Range of Motion: Opening less than 35 mm (adult norm).

  5. Muscle Fatigue: Early tiredness when chewing.

  6. Clicking/Popping: Audible sounds during jaw movement.

  7. Headaches: Tension-type headaches radiating from temples.

  8. Ear Pain: Referred pain to the ear region.

  9. Neck Pain: Secondary muscle tension in the cervical area.

  10. Facial Swelling: Inflammation of muscle tissue.

  11. Facial Asymmetry: Hypertrophy or atrophy of one muscle group.

  12. Deviation of Jaw: Mandible moves off-center when opening.

  13. Locking: Jaw stuck in open or closed position.

  14. Crepitus: Grating sensation in the joint area.

  15. Chewing Difficulty: Avoiding hard foods.

  16. Voice Changes: Slight alteration due to muscle tension.

  17. Dizziness: Rare, from associated neck muscle tension.

  18. Sleep Disturbances: Grinding at night disrupts rest.

  19. Anxiety: Fear of pain during eating.

  20. Reduced Bite Force: Measurable decrease in chewing strength.

Diagnostic Tests

  1. Clinical Palpation: Tenderness mapping of muscle sites.

  2. Range of Motion Measurement: Using a ruler or caliper.

  3. Orthopedic Provocation Tests: Pain on resisted movement.

  4. Pain Drawings: Patient marks areas of discomfort.

  5. Jaw Tracking: Electronic recording of movement patterns.

  6. Electromyography (EMG): Measures muscle activity.

  7. Pressure Pain Threshold Algometry: Quantifies sensitivity.

  8. Ultrasound Imaging: Evaluates muscle thickness and lesions.

  9. Magnetic Resonance Imaging (MRI): Visualizes soft tissues.

  10. Computed Tomography (CT)/CBCT: Bone and joint detail.

  11. X-ray (Panoramic): Baseline joint structure.

  12. TMJ Arthrography: Contrast study of joint space.

  13. Dynamic MRI: Real-time jaw movement.

  14. Blood Tests: CK levels, inflammatory markers (ESR/CRP).

  15. Rheumatoid Factor/ANA: Autoimmune screening.

  16. Vitamin D/B₁₂ Levels: Nutritional status.

  17. Electrolyte Panel: Calcium, magnesium, potassium.

  18. Sleep Bruxism Monitoring: EMG during polysomnography.

  19. Occlusal Analysis: Bite force sensors.

  20. DC/TMD Protocol: Standardized diagnostic criteria PMC.

Non-Pharmacological Treatments

  1. Soft Diet: Reduces muscle load.

  2. Heat Therapy: Promotes blood flow.

  3. Cold Packs: Decreases inflammation.

  4. Jaw Rest: Avoid wide yawning or hard foods.

  5. Physical Therapy: Guided exercises for strength and flexibility Harkins Pain & Sleep Management Group.

  6. Massage: Relieves trigger points.

  7. Stretching Exercises: Improves range of motion.

  8. Postural Training: Corrects neck/jaw alignment.

  9. Biofeedback: Teaches muscle relaxation.

  10. Cognitive Behavioral Therapy: Addresses stress-related clenching.

  11. Acupuncture: Modulates pain pathways.

  12. Dry Needling: Releases myofascial trigger points.

  13. Transcutaneous Electrical Nerve Stimulation (TENS): Pain relief via electrical stimulation.

  14. Ultrasound Therapy: Deep heat for soft tissues.

  15. Low-Level Laser Therapy: Accelerates healing.

  16. Occlusal Splints/Night Guards: Protects teeth, reduces bruxism.

  17. Orthotic Devices: Stabilizes the jaw in a neutral position.

  18. Arthrocentesis: Flushes inflammatory mediators (minimally invasive).

  19. Manual Therapy: Joint mobilization techniques.

  20. Myofascial Release: Gentle fascia stretching.

  21. Craniosacral Therapy: Light touch to balance cranial bones.

  22. Chiropractic Adjustment: Cervical spine alignment.

  23. Yoga & Stretching: Whole-body muscle relaxation.

  24. Meditation & Mindfulness: Stress reduction.

  25. Progressive Muscle Relaxation: Systematic tensing/relaxing.

  26. Ergonomic Workspace: Prevents forward-head posture.

  27. Hydrotherapy: Warm baths to relax muscles.

  28. Nutrition Counseling: Anti-inflammatory diet.

  29. Trigger Point Injections (Dry vs. Wet): Local anesthesia or saline.

  30. Ultrasound-Guided Hydrodissection: Separates fascial adhesions SpringerLink.

Pharmacological Treatments

  1. Ibuprofen (NSAID): Reduces inflammation.

  2. Naproxen (NSAID): Long-acting pain relief.

  3. Acetaminophen: Mild analgesia.

  4. Diclofenac Gel: Topical anti-inflammatory.

  5. Cyclobenzaprine: Muscle relaxant.

  6. Tizanidine: Centrally acting relaxant.

  7. Baclofen: GABA agonist for spasm relief.

  8. Thiocolchicoside: Skeletal muscle relaxant SpringerLink.

  9. Low-Dose Amitriptyline: Neuropathic pain modulation.

  10. Duloxetine: SNRI for chronic musculoskeletal pain.

  11. Gabapentin: Adjunct for neuropathic features.

  12. Clonazepam: Short-term bruxism control.

  13. Diazepam: Anxiolytic and muscle relaxant.

  14. Prednisone: Short taper for severe myositis.

  15. Methylprednisolone Injections: Local anti-inflammatory.

  16. Botulinum Toxin: Reduces muscle overactivity.

  17. Lidocaine Patch: Topical analgesia.

  18. Capsaicin Cream: Desensitizes nociceptors.

  19. Opioids (short course): Severe acute pain.

  20. NSAID/Corticosteroid Combinations: For refractory cases.

Surgical Treatments

  1. Arthrocentesis: Joint lavage under local anesthesia.

  2. Arthroscopy: Minimally invasive joint cleaning and release.

  3. Arthroplasty: Open joint surgery to repair or reposition disc.

  4. Discectomy: Removal of damaged articular disc.

  5. Disc Repositioning: Securing the disc back in place.

  6. Condylectomy: Removal of part of the mandibular condyle.

  7. Total TMJ Replacement: Prosthetic joint for end-stage disease.

  8. Coronoidectomy: Removing coronoid process to increase mouth opening.

  9. Masseter Muscle Reduction: Surgical trimming for hypertrophy.

  10. Orthognathic Surgery: Corrects jaw misalignment contributing to muscle strain NIDCR.

Prevention Strategies

  1. Stress Management: Meditation and relaxation exercises.

  2. Night Guard Use: Prevents teeth grinding during sleep.

  3. Proper Posture: Ergonomic workstation and head-neck alignment.

  4. Avoid Hard Foods: Limits excessive muscle load.

  5. Regular Jaw Exercises: Maintains flexibility.

  6. Frequent Breaks: During prolonged mouth opening (e.g., dental work).

  7. Hydration & Nutrition: Supports muscle health.

  8. Balanced Bite: Orthodontic or restorative correction of malocclusion.

  9. Limit Parafunction: Avoid nail-biting or pen chewing.

  10. Routine Dental Check-Ups: Early detection of occlusal issues.

When to See a Doctor

Seek professional evaluation if you experience persistent jaw pain lasting more than two weeks, limitation in mouth opening (< 35 mm), severe swelling, fever, or symptoms interfering with eating and speaking. Early intervention can prevent chronic progression and improve treatment outcomes NIDCR.

Frequently Asked Questions

  1. What are the primary muscles of mastication?
    The masseter, temporalis, medial pterygoid, and lateral pterygoid muscles work together to move your jaw during chewing.

  2. How is myalgia different from myositis?
    Myalgia is muscle pain without inflammation; myositis involves actual inflammation of muscle fibers.

  3. Can stress really cause jaw muscle disorders?
    Yes, stress often leads to clenching or grinding (bruxism), which can fatigue and injure chewing muscles Frontiers in Oral Medicine.

  4. Are mastication muscle disorders permanent?
    Most cases improve with conservative treatments; chronic cases need multidisciplinary care.

  5. Is imaging always required for diagnosis?
    No—many diagnoses are clinical. Imaging is reserved for complex or refractory cases.

  6. Can children get mastication muscle problems?
    Rarely, but habits like thumb-sucking or trauma can predispose them.

  7. What exercises help jaw muscle pain?
    Gentle opening-closing, side-to-side movements, and resisted opening exercises guided by a therapist.

  8. Does a night guard cure bruxism?
    It protects teeth and reduces muscle overuse but doesn’t address underlying causes.

  9. Are there dietary recommendations?
    Soft, easy-to-chew foods reduce stress on muscles during flare-ups.

  10. When is surgery necessary?
    Only for structural damage (e.g., disc displacement) unresponsive to conservative or medical therapy.

  11. Can physical therapy alone resolve these disorders?
    Often yes, especially when combined with behavioral and relaxation techniques Harkins Pain & Sleep Management Group.

  12. Is botulinum toxin safe for jaw muscles?
    In experienced hands, it can reduce hyperactivity without major side effects.

  13. How long do muscle relaxants take to work?
    Some (e.g., cyclobenzaprine) start helping within hours; a full course may last two weeks.

  14. Can posture affect jaw muscle health?
    Yes—forward head posture increases tension on chewing muscles.

  15. What lifestyle changes can help prevent recurrence?
    Incorporate regular jaw exercises, stress management, ergonomic corrections, and avoid parafunctional habits.

Disclaimer: Each person’s journey is unique, treatment plan, life style, food habit, hormonal condition, immune system, chronic disease condition, geological location, weather and previous medical  history is also unique. So always seek the best advice from a qualified medical professional or health care provider before trying any treatments to ensure to find out the best plan for you. This guide is for general information and educational purposes only. Regular check-ups and awareness can help to manage and prevent complications associated with these diseases conditions. If you or someone are suffering from this disease condition bookmark this website or share with someone who might find it useful! Boost your knowledge and stay ahead in your health journey. We always try to ensure that the content is regularly updated to reflect the latest medical research and treatment options. Thank you for giving your valuable time to read the article.

The article is written by Team Rxharun and reviewed by the Rx Editorial Board Members

Last Updated: April 24, 2025.

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