Not narrow.

If you want to sing high notes comfortably, you must first sing midrange and low notes comfortably without any distortion. Then practice the notes between the middle range and the high range (we call it the transition range) until you feel comfortable, and then your high range will naturally feel comfortable.

As for the bottom of the throat you are talking about, I am used to talking about the bottom of the throat. That is indeed a good place, if you can not involve the strength of the base of the tongue and the bottom of the chin.