An extremely simple and idealized two-dimensional model introduces this study of the natural design of the mammalian masticatory apparatus. The model treats the jaw as a lever with joint forces at one end, the output or bite forces at and near the opposite end, and the input muscle force somewhere in the middle. Results are constantly compared with the condition in real animals. The major result is that all the teeth will be located in front of the line-of-action of the imagined resultant force of the jaw muscles. The next two results are closely related. First, the line-of-action of the imagined resultant muscle force will be located about one-third of the jaw length from the jaw joint. Second, this location maximizes the sum of the bite forces along the entire length of the tooth row.

The location of the line-of-action is critical, because if the idealized moment arm of the muscles is fixed, then the lever system is also fixed. Bite forces then are determined only by the amount of muscle tissue available.