Knife tool

I’m trying to model an alien head, and I’d like to use the knife tool to make extra detail for the eye, but when I do so blender creates a lot of edges but I only need an extra vertex. Is there any way I can put a vertex between two vertices without creating extra edges?

Here’s what I’m trying to do.
http://img.photobucket.com/albums/v634/Pensacola/alien2.jpg

I need edges where the red lines are, but not anywhere else…

Greets, Pol

Blender uses 3 or 4 edges to make a face, no more. So NGons are not recognized. That’s why, when you subdivide an edge extra edges are created. You either have to model with this in mind or remake quad faces from the triangles produced. You get used to it after a while (you also get used to doing everything with pencil and paper before modelling!)

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