The human body has a variety of points where if enough pressure is applied causes the body to become all limp and floppy, or even cause your attacker to blackout, due to you shortcircuiting their blood supply ony just for afew seconds.

These Points are exposed and should be usually exposed so striking these points should prove easy, providing you to apply as much pressure or force to these areas as is required either to subdue your attacker or cause them ingury If you at serious risk.
There are a variety of ways to strike these points and techniques which I will go through In the next section at a Later date. ;)