  We study the Wigner functions of the nucleon which provide multidimensional
images of the quark distributions in phase space and combine in a single
picture all the information contained in the generalized parton distributions
(GPDs) and the transverse-momentum dependent parton distributions (TMDs). In
particular, we present results for the distribution of unpolarized quark in a
longitudinally polarized nucleon. Treating this distribution as it was a
classical distribution, we also obtain the expectation value of the orbital
angular momentum operator and compare the corresponding results from different
quark models with the values obtained using alternative definitions of the
orbital angular momentum, as given in terms of the GPDs and the TMDs.
