Oh, sorry! The metatarsals are the "knuckles" of the ball of your foot. If you have a dropped met head, it means the normal arch of your forefoot that goes left to right from big toe to pinky toe is "dropped" at one of the met heads. That particular met head has sunk down a little from the arch the rest of them are trying to hold.

The easiest way to see if you have one is to look at the sole of your foot, at the ball. Often you will get a big ol' callous under a dropped met head (mine was under my 2nd toe knuckle) When that met arch flattens the nerves running through the ball of the foot get sqeezed, there's less room in a flattened met arch.

If you've already got a neuroma, the pressure from a flattened met arch can take it from being an occaisional irritant to being unending misery. (mine did that.) If you don't have a neuroma already, a flattened met arch can give you some of the symptoms of one, but it won't be anything like the level of misery caused by a true neuroma!