How Stun Guns work
The basic idea of a stun gun is to disrupt the body's nervous system communication system. Stun guns generate a high-voltage, low-amperage electrical charge. In simple terms, this means that the charge has a lot of painful pressure behind it, but not that much intensity. When you press the stun gun against an attacker and hold the trigger, the charge passes into the attacker's body. Since it has a very high voltage, the charge will pass through heavy clothing and skin. But at around 3 milliamps, the charge is not intense enough to stop the attackers heart or breathing. This makes a Stun gun a very effective non-lethal self defense mechanism
The Stun gun will dump a lot of painful confusing information into the attacker's nervous system, however. This causes a couple of things to happen:
The charge combines with the electrical signals from the attacker's brain making it very difficult for the nervous system to decipher any messages. The attacker then finds telling his muscles to move almost impossible, and he will become confused and partially paralyzed, temporarily, giving you time to make your escape.
The current may be generated with a pulse frequency that mimics the body's own electrical signals. In this case, the current will tell the attacker's muscles to do a great deal of work in a short amount of time. But the signal doesn't direct the work toward any particular movement. The work doesn't do anything but deplete the attacker's energy reserves, leaving him too weak to move.
At its most basic, this is all there is to incapacitating a person with a stun gun -- you apply electricity to a person's muscles and nerves. And since there are muscles and nerves all over the body, it doesn't particularly matter where you hit an attacker.