  Nonzero masses for the active neutrinos - regardless of their nature or
origin - arise only after electroweak symmetry breaking. We discuss the
parameterization of neutrino couplings to a Higgs sector consisting of one
SU(2)_L scalar doublet and one SU(2)_L scalar triplet, and allow for
right-handed neutrinos whose Majorana mass parameters arise from the vacuum
expectation value of a Standard Model scalar singlet. If the neutrinos are
Majorana fermions, all Yukawa couplings can be expressed as functions of the
neutrino mass eigenvalues and a subset of the elements of the neutrino mixing
matrix. In the mass basis, the Yukawa couplings are, in general, not diagonal.
This is to be contrasted to the case of charged-fermions or Dirac neutrinos,
where couplings to the Higgs-boson are diagonal in the mass basis and
proportional only to the fermion masses. Nonetheless, all physically
distinguishable parameters can be reached if all neutrino masses are
constrained to be positive, all mixing angles constrained to lie in the first
quadrant (theta in [0,pi/2]), and all Majorana phases to lie in the first two
quadrants (phi in [0,pi]), as long as all Dirac phases vary within the entire
unit circle (delta in [0,2pi}). We discuss several concrete examples and
comment on the Casas-Ibarra parameterization for the neutrino Yukawa couplings
in the case of the type-I Seesaw Lagrangian.
