@Laurent2000 and references therein] the MIR emission of spiral galaxies observed by ISOCAM originates from a number of physical processes, with two dust heating mechanisms typically prevailing. One is the thermal emission produced by thermally-fluctuating, small grains ($\sim$10nm) heated by the interstellar radiation field, observed between 12$\mu$m and 18$\mu$m in areas of strong radiation environments and is often sampled by the LW3 filter. The second is due to the UIBs, which originated from complex 2-dimensional aromatic molecules having C=C and C–H bonds and can be seen at 6.2, 7.7, 8.6, 11.3 and 12.7$\mu$m in the ISOCAM wavelength range. The emission in these bands can be observed either with the CVF or using a sequence of narrow-band filters. An absorption feature due to silicates is often observed at 9.7$\mu$m and can be measured using the LW7 (8.5-10.7$\mu$m) filter. Finally, two forbidden emission lines due to \[NeII\] at 12.8$\mu$m and \[NeIII\] at 15.5$\mu$m can be detected in the CVF mode. A contribution to the MIR spectrum by a third component, the Rayleigh-Jeans tail of an old stellar population, is generally negligible in late type galaxies where the hot dust emission dominates. This MIR emission directly arising from stellar photosphere is detected in 