Head injury

A head injury is what happens when you hurt your head... like really bad. Mind you, this is not a neck, stomach, leg of toe injury. Head injuries can range from mundane superficial damage like bumping your nugget on a low archway to the severe like having your melon completely caved in by a sledgehammer. Head injuries of the latter variety tend to often be fatal as well.

Some times of head injuries may affect brain activity as well. When a body makes a serious impact with an object of high resistance, it may cause the brain to slam against the inside of the skull, causing a loss of cognitive function. This is commonly referred to as a concussion. This may also result in either temporary or permanent amnesia, which is when you forget who... umm... when you can't recall your... err... it's when you can't 'member stuff!

Naturally, the removal of either the brain or head is the most radical form of head injury. In most cases, such an extreme occurrence is almost always fatal. You can't live without a head. According to B.O.B. from Monsters vs. Aliens, you don't really need your brain all that much either.

If you've ever watched the NBC television series Heroes, then you know that nobody causes greater headaches (both literally and figuratively) than everyone's favorite psychopath, Gabriel Gray, aka Sylar. As an evolved human, Sylar possessed the ability to automatically comprehend brain functions through casual examination. But because he's a murderous whack-a-doodle, he can only develop this understanding through direct observation. To accomplish this, Sylar would telekinetically cut open a person's head, scoop out the soup, and see what's going on. By analyzing the brain of an evolved human, he was able to adjust his own biology to suit, thus duplicating their powers.