In our histological material the anterior process of the malleus appears to be attached to the wall of the middle-ear cavity by a large but thin layer of amorphous material. This has been crudely represented by using a spring at each corner of a triangular element representing the thin bony web between the neck and anterior process of the malleus, as shown in Fig. 4. 6 shows the displacements as vectors. The axis of rotation runs roughly parallel to the expected line from the anterior mallear tip to the posterior incudal tip. Green and red contours represent displacements out of and into the page, respectively.
Black contours correspond to zero displacement.
Green arrows point out of the page, red arrows point into the page. The arrow lengths are normalized to the overall maximum component value of 296 nm. 7 and 8 show the model's displacements when the stiffnesses are all either decreased or increased by a factor of 2, and then by a factor of 100. The model presented here includes a rough approximation for the geometry of the cat malleus and incus, and of the soft tissue suspending them from the wall of the middle-ear cavity, and plausible estimates for the material properties. The model produces a low-frequency displacement pattern and an axis of rotation which are similar to experimental observations.