Page 177 - Visions of the Future Chemistry and Life Science

158 P. J. KOLSTON

middle

inner

outer
Figure 9.3. The human ear is divided into three main parts. The outer ear collects
sound and directs it down the ear canal towards the eardrum. The size of the
eardrum, combined with the lever action of the three bones of the middle ear,
ensures the efficient conduction of sound from the ear canal, which is filled with
air, to the inner ear, which is filled with a liquid. Very small muscles, not shown
here, are connected to these bones to protect the ear from very loud sounds. The
inner ear consists of two parts. Only the cochlea is shown, which is the part of the
human ear that is responsible for converting sound into electrical signals in the
auditory nerve. The other part of the inner ear, the vestibular organ, is involved in
balance.

Finite-element techniques can cope with large, highly non-linear def-
ormations, making it possible to model soft tissues such as skin. When rel-
atively large areas of skin are replaced during plastic surgery, there is a
problem that excessive distortion of the applied skin will prevent adequate
adhesion. Finite-element models can be used to determine, either by rapid
trial-and-error modelling or by mathematical optimisation, the best way of