What is trismus?

What is trismus?

• A. Lockjaw due to infection of the jaw muscles
• B. Inability to smile due to facial nerve palsy
• C. Difficulty chewing caused by dental issues
• D. Inability to open the mouth due to a tonic contraction of the jaw muscles

Answer: (D)

Trismus is the inability or severe limitation to open the mouth because the jaw muscles are in a tonic, involuntary contraction. This spasm of the masticatory muscles, especially the masseter and temporalis, prevents normal mouth opening and can occur with conditions like tetanus or other causes of jaw muscle hypertonicity. That’s why the statement describing an inability to open the mouth due to a sustained contraction of the jaw muscles is the best fit. While lockjaw is a term you might hear, the idea that it’s simply an infection of the jaw muscles isn’t precise; trismus centers on the muscle spasm causing restricted opening, not necessarily an infection of the muscles themselves. Inability to smile from facial nerve palsy or chewing difficulty from dental issues describe different problems and don’t capture the specific mechanism of restricted mouth opening from jaw muscle contraction.

Trismus is the inability or severe limitation to open the mouth because the jaw muscles are in a tonic, involuntary contraction. This spasm of the masticatory muscles, especially the masseter and temporalis, prevents normal mouth opening and can occur with conditions like tetanus or other causes of jaw muscle hypertonicity. That’s why the statement describing an inability to open the mouth due to a sustained contraction of the jaw muscles is the best fit.

While lockjaw is a term you might hear, the idea that it’s simply an infection of the jaw muscles isn’t precise; trismus centers on the muscle spasm causing restricted opening, not necessarily an infection of the muscles themselves. Inability to smile from facial nerve palsy or chewing difficulty from dental issues describe different problems and don’t capture the specific mechanism of restricted mouth opening from jaw muscle contraction.