Locked jaw or masseter muscle
spasm can occur due to (1) tetanus toxoid
or tetanus; (2) bad bite or misadjustment of the tempero-mandibular joint (TMJ) leading to spasm; (3) advanced ageing when continuous grinding of the teeth can lead to lock jaw.
Succinylcholine is a short acting muscle relaxant
, a depolarising neuromuscular blocker, that relaxes the muscles and is used as an aid to tracheal intubation
in such cases. It has the fastest onset of action compared to other drugs and hence a favourite in emergency settings.
Hope that answers your query.