[Reaction of the tympanic tensor muscle--elicited by nasally applied trigeminal stimulants].

Computerised evaluation of tensor muscle reaction was carried out by using a biosignal analysing unit triggered by nasal inhalation. The trigeminus nerve was stimulated by application of 3-molar acetylacetic acid into the nasal respiratory air, inducing a contraction of the tympanic muscle, followed by a change in impedance. This change in impedance of the tympanic membrane ossicle system was recorded and printed out on a display. In this manner evidence was obtained of a tensor muscle reaction induced by the third branch of the trigeminal nerve as efference, and demonstrated for the first time. This reflex arc had long been considered as being of negligible clinical importance before its stimulation and measurement had become possible. It is a generally accepted theory that the reflex arc of the m. tensor tympani is linked to the formatio reticularis which assesses the sensory afferences. For this reason, the reflex arc habituates rapidly, and continuous stimulation is no longer possible.