Tendon Reflexes Posted on 17th November 2016 by gcs3 Here are a couple of mnemonics for remembering the roots S1-2: buckle my shoe (ankle) L3-4: Kick the door (Knee) C5-6: pick up sticks (Biceps) C7-8: lay them straight (Triceps) Deep tendon reflexes: root supply “1,2,3,4,5,6,7,8”: S1-2: ankle L3-4: knee C5-6: biceps, supinator C7-8: triceps