  Scalar, baryon and vector--current densities in coordinate and momentum space
are calculated within a relativistic mean--field model. The role of the low
components of the bound nucleon wave function is investigated in detail for
different spin--orbit partner shells. We show that the relative importance of
the negative--energy projection components can be explained from the different
quantum numbers involved in the relativistic wave function. This fact has
proved to be important in the analysis of various electron scattering
observables even for low--medium values of the bound nucleon momentum.
