  We discuss the Wigner functions of the nucleon which provide
multi-dimensional images of the quark distributions in phase space. They
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 quarks in a longitudinally polarized nucleon obtained in a
light-cone constituent quark model. We show how quark orbital angular momentum
can be extracted from these distributions and compare it with alternative
definitions given in terms of the GPDs and the TMDs.
