Why don't some parts of my body sweat?

Whenever I'm in the Sauna, the only parts that are drenched with sweat are my forehead, my neck and especially my back. None of the other parts don't sweat, or sweats very little. Why?
Why don't some parts of my body sweat?
Some parts of the body have less sweat glands than other parts and these body parts are different for each person. For instance, some people have very sweaty hands and feet. In your case, it sounds like your neck and back have more sweat glands than other parts of your body.