Observations on the blink reflex.

The blink reflex and its equivalent glabella tap reflex are behavioural motor responses normally found in neonates and in the physiological startle reflex. Historically, it was described by Overend in 1896 and soon afterwards by McCarthy and by Bekhterev who disputed its origins. Kugelberg in 1952 recorded the early-latency R1 and the late-latency R2 electromyographic responses from orbicularis oculi and considered the blink reflex to be 'a true skin reflex'. The mechanisms and clinical diagnostic value are discussed.