Question

Trismus is most commonly due to spasm or involvement of which muscle?

• A. Lateral pterygoid
• B. Medial pterygoid
• C. Masseter
• D. Temporalis

Hint:

Post-inferior alveolar nerve block trismus → Think of medial pterygoid muscle spasm.

Answer 1

The Correct Option is B

Step 1: Understanding Trismus.
Trismus refers to restricted mouth opening due to spasm, inflammation, trauma, or involvement of the muscles of masticationIt is commonly seen after inferior alveolar nerve block, infection, trauma, or surgical procedures
Step 2: Muscle Most Commonly Involved.
The medial pterygoid muscle lies close to the site of inferior alveolar nerve block injectionBecause of its anatomical proximity, it is most frequently traumatized or irritated during dental proceduresThis leads to muscle spasm and difficulty in mouth opening
Step 3: Excluding Other Options.
The lateral pterygoid is mainly involved in protrusion and opening movements
The masseter and temporalis are elevator muscles but are less commonly affected during routine dental injections
Thus, medial pterygoid involvement is the most common cause of post-injection trismus
Step 4: Conclusion.
Since the medial pterygoid muscle is most commonly involved in trismus, the correct answer is Medial pterygoid