Approximately how far can a patient with muscular myospasm (trismus from muscle spasm) typically open their mouth?

Normal maximal mouth opening is roughly 40-50+ mm. Muscle splinting/spasm classically causes a moderate restriction, often cited in the range of roughly 25-30 mm (noticeably reduced from normal but not as severely restricted as the very limited opening seen with conditions like a closed lock or severe trismus from infection, which can approach 10-20 mm or less).