  The chiral symmetry is applied to an extended constituent quark potential
model. With random phase approximation (RPA), the model comprises sea quark
excitations. To obtain the pseudoscalar $\pi$ meson as a Goldstone boson, the
quark effective potentials are modified in the model to account for the
dynamical breaking of chiral symmetry. Also the vector $\rho$ meson is
calculated and the KSRF relation about $\pi$ and $\rho$ meson decay constants
is derived in the model.
