  The objective of this work is to report on the modifications in air shower
development due to muon bremsstrahlung and muonic pair production. In order to
do that we have implemented new muon bremsstrahlung and muonic pair production
procedures in the AIRES air shower simulation system, and have used it to
simulate ultra high energy showers in different conditions.
  The influence of the mentioned processes in the global development of the air
shower is important for primary particles of large zenith angles, while they do
not introduce significant changes in the position of the shower maximum.
