Last updated: Wed, Jun 21, 2017
The crossed extensor reflex begins from 0.2 to 0.5 seconds after the flexor reflex. It's in a way the opposite of the flexor reflex: It involves the opposite side of the body, and causes the limb to extend rather than to flex. The minimal circuit needed for the crossed extensor reflex is shown in Figure 1: Crossed extensor reflex. The interneurons involved extend across the midline of the spinal cord. Since it occurs so long after the flexor reflex, it is likely that it involves many more interneurons than are shown.