A jaw spasm, medically known as trismus, is a condition where the jaw muscles become so tight that opening your mouth becomes difficult or impossible. This tightening is due to muscle spasms in the temporomandibular joint (TMJ), the joint connecting your jaw to your skull. Several factors can contribute to jaw spasms, including:
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Temporomandibular Disorders (TMD): These disorders affect the TMJ and surrounding muscles, often leading to myofascial pain (muscle spasm pain). Chronic overuse of the jaw muscles from activities like teeth grinding, clenching, or gum chewing can contribute to TMD and subsequent spasms.
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Head and Neck Cancer Treatment: Radiation therapy and surgery for head and neck cancers are common causes of trismus.
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Meige Syndrome: This neurological condition causes involuntary spasms in the facial muscles, including the jaw, eye, tongue, and lower face.
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Injury: Trauma to the jaw or surrounding areas can trigger muscle spasms. Lockjaw, a severe form of jaw spasm, can result from an injury or, more famously, a tetanus infection.
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Other Causes: Other less common causes include certain medications, infections, and neurological conditions.
While the term "jaw spasm" is commonly used, the more precise medical term is trismus. Trismus refers specifically to muscle spasms in the TMJ, resulting in limited jaw opening. Pain and stiffness are common symptoms. The pain can be severe and significantly impact daily activities like eating, speaking, and even brushing teeth.
Different sources highlight various aspects of jaw spasms: Cleveland Clinic's website defines trismus and discusses its relation to head and neck cancer treatment; other sources detail the association with TMD, Meige syndrome, and injury. The intensity of a jaw spasm can range from mild discomfort to severe lockjaw, which completely restricts jaw movement.
