There two ways of the getting of wisdom in the mouth. There is the lower impacted wisdom tooth, where the tooth has no room to fit in the corner, or angle, of the lower jaw. So the tooth is surrounded by dense lower jaw bone, tongue, cheek and near the nerve trunk within the bone. Warning, care here!

The upper wisdom tooth is at the end of the upper jaw bone. So the tooth usually is not surrounded by bone, or a tongue. However, the sinus is nearby. It is the fact the tooth is at the end of the less dense upper jaw bone, which is curved, it has to sit in bone. Therefore it follows the curve, and often, it comes out pointing into the cheek. This irritates the cheek and the muscle within it. This is not a happy situation for this muscle as it is a jaw closing muscle. The irritated muscle spasms and will not relax to allow your mouth to open. This is called trismus.