We present a theoretical study of Zeeman spin splitting for quasi-onedimensional valence-band edges in cylindrical
nanowires subject to a magnetic field parallel to the wire direction. The interplay between quantum confinement
and strong spin-orbit coupling in the valence band gives rise to a controllable large variation of the effective
<i>g</i>-factor for single wire levels. A direct correspondence is established between values for hole <i>g</i>-factors and
characteristic spin-polarization profiles for wire-level bound states. The correlation between hole spin splittings
and polarizations is mapped over the range of spin-orbit coupling strengths present in typical semiconductor
materials. We propose to use nanowire subband edges as a versatile laboratory for experimental and theoretical
study of the complex spin properties exhibited by quantum-confined holes.