  The decomposition of nuclear symmetry energy into spin and isospin components
is discussed to elucidate the underlying properties of the NN bare interaction.
This investigation was carried out in the framework of the
Brueckner-Hartree-Fock theory of asymmetric nuclear matter with consistent two
and three body forces. It is shown the interplay among the various two body
channels in terms of isospin singlet and triplet components as well as spin
singlet and triplet ones. The broad range of baryon densities enables to study
the effects of three body force moving from low to high densities.
