1. (Reflex) hammer time! A thread. 🔨 #neurotwitter#Neurology#histmed@MayoClinicNeuro@mayoneurores@AANMember2. After Erb & Westphal described muscle stretch reflexes in 1875, chest percussion hammers were used to elicit reflexes. This is a Vernon percussion hammer, the precursor of the Queen Square reflex hammer. This one was made by Whitelaw (Aberdeen, Scotland).