trismus; lockjaw
Medical term for the inability to open the mouth fully, often due to muscle spasm. Used in clinical contexts.
Trismus can appear as an early symptom of tetanus.
Some patients complain of temporary lockjaw after dental treatment.
開口障害 is a broader term for any difficulty in opening the mouth, while 牙関緊急 specifically refers to trismus caused by muscle spasm.
A Sino-Japanese medical term from Chinese 牙関緊急, literally describing the jaws as tightly closed.