The dynamic equations are obtained for the moments of the Wigner function (density matrix) in the phase space of a nucleon. The rules of closure of the set of equations for these moments are formulated. The negative-parity vibrational states (octupole, magnetic quadrupole and isoscalar dipole toroidal) are analysed. The theory gives an adequate description for all these excitations using as an input the values of the nuclear radius (R=r₀A¹3/, r₀=1.2 fm) and the surface tension (T=17/4 pi r₀² MeV fm^-2).