  We have recently examined the static properties of the baryon octet (magnetic
moments and axial vector coupling constants) in a generalized quark model in
which the angular momentum of a polarized nucleon is partly spin $\langle S_z
\rangle$ and partly orbital $\langle L_z \rangle$. The orbital momentum was
represented by the rotation of a flux-tube connecting the three constituent
quarks. The best fit is obtained with $\langle S_z \rangle = 0.08\pm 0.15$,
$\langle L_z \rangle = 0.42\pm 0.14$. We now consider the consequences of this
idea for the $q^2$-dependence of the magnetic and axial vector form factors. It
is found that the isovector magnetic form factor $G_M^{\mathrm{isovec}}(q^2)$
differs in shape from the axial form factor $F_A(q^2)$ by an amount that
depends on the spatial distribution of orbital angular momentum. The model of a
rigidly rotating flux-tube leads to a relation between the magnetic, axial
vector and matter radii, $\langle r^2 \rangle_{\mathrm{mag}} =
f_{\mathrm{spin}} \langle r^2 \rangle_{\mathrm{axial}} + \frac{5}{2}
f_{\mathrm{orb}} \langle r^2 \rangle_{\mathrm{matt}}$, where $f_{\mathrm{orb}}/
f_{\mathrm{spin}} = \frac{1}{3}\langle L_z \rangle / G_A$, $f_{\mathrm{spin}} +
f_{\mathrm{orb}} = 1$. The shape of $F_A(q^2)$ is found to be close to a dipole
with $M_A = 0.92\pm 0.06$ GeV.
