Mastication muscle infection refers to inflammation and infection of one or more of the primary muscles involved in chewing—namely the masseter, temporalis, medial pterygoid, and lateral pterygoid muscles. When a pathogen (bacterial, viral, fungal, or parasitic) invades these muscles, it leads to myositis (muscle inflammation), abscess formation, pain, swelling, and impaired jaw movement. Although inflammatory muscle diseases can also be immune-mediated (such as masticatory muscle myositis), the focus here is on infectious processes. Early recognition and treatment are vital to prevent spread to adjacent fascial spaces and deeper neck structures MedlinePlusPMC.
Anatomy of the Masticatory Muscles
Structure & Location
Masseter: A thick, rectangular muscle on the lateral side of the mandible.
Temporalis: A fan-shaped muscle filling the temporal fossa on the side of the skull.
Medial Pterygoid: A quadrangular muscle on the medial (inner) aspect of the mandible.
Lateral Pterygoid: A two-headed muscle situated deep in the infratemporal fossa. Wikipedia
Origin & Insertion
Masseter: Originates from the zygomatic arch; inserts on the lateral surface of the mandibular ramus.
Temporalis: Originates from the temporal fossa; inserts on the coronoid process and anterior border of the mandibular ramus.
Medial Pterygoid: Originates from the medial surface of the lateral pterygoid plate and palatine bone; inserts on the medial mandibular ramus.
Lateral Pterygoid: Superior head originates from the greater wing of the sphenoid; inferior head from the lateral pterygoid plate; both insert on the pterygoid fovea of the mandibular condyle Wikipedia.
Blood Supply
Primarily from branches of the maxillary artery—masseteric artery (masseter), deep temporal arteries (temporalis), pterygoid branches (pterygoids) Wikipedia.
Nerve Supply
All four muscles receive motor innervation from the mandibular division (V₃) of the trigeminal nerve:
Masseteric nerve → masseter
Deep temporal nerves → temporalis
Medial and lateral pterygoid nerves → respective muscles Wikipedia.
Primary Functions
Elevation of the mandible (closing the jaw)
Protrusion (pushing the jaw forward)
Retraction (pulling the jaw backward)
Lateral excursion (side-to-side grinding)
Stabilization of the mandible during speech
Assisting swallowing by positioning the mandible NCBI.
Types of Mastication Muscle Infections
Acute Infectious Myositis
Rapid onset due to bacterial invasion (e.g., Staphylococcus aureus, Streptococcus spp.) with pain, swelling, fever.
Chronic Infectious Myositis
Slow progression (e.g., tuberculosis, actinomycosis) with granuloma formation and fibrosis.
Viral Myositis
Often due to influenza or enteroviruses; presents with diffuse muscle pain.
Fungal Myositis
Rare; seen in immunocompromised patients (e.g., Candida, Cryptococcus).
Parasitic Myositis
Caused by organisms like Trichinella spiralis; leads to muscle fiber invasion.
Masticatory Muscle Abscess
Causes
Dental infections (pericoronitis, pulpal necrosis) Wikipedia
Mandibular fractures with contamination Wikipedia
Post-operative infections after oral surgery
Hematogenous spread from distant foci (e.g., endocarditis) PMC
Tetanus toxin causing sustained spasm and secondary muscle damage
Influenza virus leading to viral myositis MedlinePlus
COVID-19 related myositis (documented case reports)
Tuberculosis of the masticatory muscles PMC
Actinomycosis extending from jaw abscess
Trichinellosis via ingestion of undercooked meat PMC
Dermatomyositis (infection-triggered flare) MedlinePlus
Polymyositis (infection as precipitant) MedlinePlus
Retrograde infection via parotid duct
HIV/AIDS immunosuppression leading to opportunistic myositis
Steroid therapy reducing immunity
Diabetes mellitus predisposing to bacterial spread
Malnutrition weakening local defenses
Radiation therapy causing mucosal breakdown
Animal bites transmitting anaerobic bacteria
Iatrogenic inoculation (intramuscular injections) MedlinePlusPMC.
Symptoms
Localized pain worsened by chewing
Swelling over the jaw or temple area
Tenderness on palpation
Trismus (limited mouth opening) NCBI
Fever and chills
Malaise and fatigue
Muscle weakness in jaw closure
Erythema overlying skin
Crepitus if gas-forming organisms present
Dysphagia (difficulty swallowing)
Odynophagia (painful swallowing)
Otalgia (referred ear pain)
Halitosis (bad breath) if abscess drains orally
Enlarged lymph nodes in neck or submandibular region Wikipedia
Headache
Mandibular deviation on opening
Facial asymmetry in swelling
Weight loss secondary to poor oral intake
Night sweats (in chronic infections)
Elevated inflammatory markers (ESR, CRP) PMC.
Diagnostic Tests
Complete blood count (CBC) – leukocytosis
Erythrocyte sedimentation rate (ESR) – elevated
C-reactive protein (CRP) – elevated PMC
Blood cultures – identify bacteremia
Ultrasound – detect fluid collections
Contrast-enhanced CT scan – delineate abscess & deep spread
MRI – show muscle edema and inflammation
Needle aspiration – obtain pus for culture
Gram stain & culture – identify bacteria
Acid-fast bacilli stain – for mycobacterial infection
Fungal cultures – for fungal pathogens
Serology – viral myositis (e.g., influenza)
Muscle biopsy – confirm myositis type
Autoimmune panels – rule out dermato/polymyositis
Electromyography (EMG) – assess muscle function
Creatine kinase (CK) – elevated in muscle damage
Monoclonal antibodies assay – for masticatory muscle myositis (2M fiber) vetneuromuscular.ucsd.edu
Ultrasound-guided biopsy – precise tissue sampling
PCR assays – viral or mycobacterial DNA
Procalcitonin – marker for severe bacterial infection PMC.
Non-Pharmacological Treatments
Warm compresses to reduce pain
Cold packs to decrease swelling
Gentle jaw stretching exercises NCBI
Soft diet to minimize chewing
Good oral hygiene to prevent spread
Hydration to support healing
Rest of the masticatory muscles
Ultrasound therapy for deep heat
Electrical muscle stimulation
Massage therapy to improve circulation
Physiotherapy for jaw mobilization
Transcutaneous electrical nerve stimulation (TENS)
Low-level laser therapy
Acupuncture for pain relief
Stress management (to reduce muscle clenching)
Biofeedback for muscle control
Dental splints/night guards NCBI
Speech therapy if swallowing is affected
Positioning pillows to avoid pressure on jaw
Heat-moist towel packs
Oral myofunctional therapy
Infrared lamps
Hydrocolloid dressings on extra-oral swelling
Lymphatic drainage massage
Guided imagery/relaxation techniques
Dietary counseling for nutrition
Avoidance of aggravating activities (e.g., gum chewing)
Jaw rest appliances
Magnetic therapy (adjunctive)
Cold laser acupuncture PMC.
Drugs
Amoxicillin-clavulanate (broad-spectrum antibiotic)
Clindamycin (anaerobic coverage)
Cephalexin (first-generation cephalosporin)
Ceftriaxone (third-generation cephalosporin)
Metronidazole (for anaerobes)
Vancomycin (MRSA coverage)
Linezolid (MRSA & VRE)
Doxycycline (tick-borne pathogens, some atypicals)
Levofloxacin (Gram-negative coverage)
Piperacillin-tazobactam (broad coverage)
Meropenem (severe infections)
Itraconazole (fungal myositis)
Amphotericin B (severe fungal)
Albendazole (parasitic myositis)
Prednisone (for immune-mediated component)
Methotrexate (steroid-sparing in MMM) vetneuromuscular.ucsd.edu
Azathioprine (immunosuppression)
Intravenous immunoglobulin (IVIG) (autoimmune)
Ibuprofen (NSAID for pain)
Acetaminophen (analgesic & antipyretic) MedlinePlus.
Surgeries
Incision and drainage of abscess (intraoral or extraoral) Wikipedia
Wide debridement of necrotic muscle
Myotomy (in chronic contracture)
Coronoidectomy (to improve mouth opening)
Mandibular osteotomy (for severe jaw deviation)
Temporalis flap reconstruction (post-debridement)
Microvascular free flap (for large defects)
Neurectomy (in refractory spasm)
Temporomandibular joint (TMJ) release
Scar revision surgery (in chronic stages) Wikipedia.
Prevention Strategies
Prompt dental care for infections
Protective gear to prevent facial trauma
Strict asepsis during oral procedures
Immunizations (tetanus, influenza)
Good glycemic control in diabetes
Nutrition optimization
Avoiding undercooked meat (prevent trichinellosis)
Timely treatment of systemic infections
Regular dental check-ups
Sterile technique for intramuscular injections PMC.
When to See a Doctor
Seek medical attention immediately if you experience:
Severe jaw pain with high fever
Inability to open or close your mouth
Rapidly spreading facial swelling
Difficulty breathing or swallowing
Signs of systemic infection (e.g., chills, confusion) PMC.
Frequently Asked Questions (FAQs)
What causes mastication muscle infections?
Bacteria from dental infections or trauma often spread into chewing muscles, causing infection.Can viral infections affect chewing muscles?
Yes—viruses like influenza can invade and inflame these muscles.How is a masticatory muscle abscess treated?
Incision and drainage plus appropriate antibiotics usually resolve it.Is jaw stiffness always an infection?
No—trismus can result from TMJ disorders, but infection is likely when fever and swelling accompany stiffness.Are imaging tests necessary?
Often—CT or MRI helps locate abscesses and plan drainage.Can I treat it at home?
Home remedies (warm compress, soft diet) help comfort, but antibiotics and possible drainage are essential.How long does recovery take?
With prompt treatment, most resolve in 1–2 weeks; chronic cases may take months.Can it recur?
Yes—especially if underlying dental issues are not addressed.Are there risks of spread?
Without treatment, infection can extend into deep neck spaces, causing life-threatening complications.Do I need surgery?
If an abscess forms, surgical drainage is required.Can diabetes worsen it?
Poor blood sugar control increases infection risk and severity.What role do physiotherapy exercises play?
They help restore jaw mobility after acute inflammation subsides.Is masticatory muscle myositis the same as infection?
No—myositis can be immune-mediated without any infection.How do I prevent it?
Good dental hygiene, prompt treatment of oral infections, and avoiding facial trauma are key.When is hospitalization needed?
If you have high fever, airway compromise, or rapid spread of swelling, inpatient care is advised.
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The article is written by Team Rxharun and reviewed by the Rx Editorial Board Members
Last Updated: April 24, 2025.
