What condition is described by the inability to open the jaw due to pain?

The condition characterized by the inability to open the jaw due to pain is known as trismus. This term specifically refers to the restricted range of motion in the jaw, often resulting in difficulty or inability to fully open the mouth. Trismus can arise from various causes, including trauma, dental issues, infections, or muscle spasms. The pain associated with trismus typically results from inflammation or tension in the muscles that control jaw movement.

While other conditions might also involve jaw pain or movement issues, they do not capture the specific inability to open the jaw due to pain that defines trismus. For example, bruxism refers to teeth grinding, typically occurring during sleep, which does not inherently involve the inability to open the jaw. TMJ (temporomandibular joint) disorder can involve jaw pain and movement limitations but is often associated with additional symptoms like clicking sounds or joint dysfunction. A jaw fracture would also lead to pain and potential difficulty opening the jaw, but it typically presents with more severe trauma indicators and specific physical signs of fracture, rather than the broad definition of trismus.