IInclusion Criteria:

• Adults aged 18-40 years.
• Patients diagnosed with temporomandibular joint dysfunction.
• Patients scheduled to undergo temporomandibular joint arthrocentesis.
• Ability to undergo ultrasonographic and strain elastographic evaluation of the masseter muscle.
• Written informed consent provided.

Exclusion Criteria:

• Previous temporomandibular joint surgery.
• History of trauma, cyst, tumor, or infection involving the temporomandibular joint or masseter muscle.
• Neuromuscular disorders affecting the masticatory muscles.
• Systemic diseases or medications that may affect masseter muscle thickness or elasticity.
• Inability or unwillingness to provide written informed consent.