  We developed a new and unified scheme for describing both quark spin and
orbital angular momenta in symmetry-breaking chiral quark model. The loss of
quark spin in the chiral splitting processes is compensated by the gain of the
orbital angular momentum carried by quarks and antiquarks. The sum of both spin
and orbital angular momenta carried by quarks and antiquarks is 1/2. The
analytic and numerical results for the spin and orbital angular momenta carried
by quarks and antiquarks in the nucleon are given. Extension to other octet and
decuplet baryons is also presented. Possible modification and application are
discussed.
