  We present a microscopic description of the strong $\pi NN$, $\pi N\Delta$
and $\pi\Delta\Delta$ vertices. Our starting point is a constituent-quark model
supplemented by an additional $3q\pi$ non-valence component. In the spirit of
chiral constituent-quark models, quarks are allowed to emit and reabsorb a
pion. This multichannel system is treated in a relativistically invariant way
within the framework of point-form quantum mechanics. Starting with a common
$SU(6)$ spin-flavor-symmetric wave function for $N$ and $\Delta$, we calculate
the strength of the $\pi NN$, $\pi N\Delta$ and $\pi\Delta\Delta$ couplings and
the corresponding vertex form factors. Our results are in accordance with
phenomenological fits of these quantities that have been obtained within purely
hadronic multichannel models for baryon resonances.
