<prompt> While giving IANB nerve block, postoperatively the patient complains of trismus due to:Injection into buccinatorInjection into parotid capsuleInjection into medial pterygoidParalysis of nerve  <response>: Trismus is inability to open mouth due to muscle spasm. It is caused by injection into medial pterygoid muscle resulting in hematoma formation or infection. The application of heat and administration of antibiotics relieve the symptoms. 