  We describe two independent methods to calculate the angular distribution of
muons after traversing a thick scatterer due to multiple Coulomb scattering.
Both methods take into account the nuclear size effect. We demonstrate a
necessity to account for the nucleus extension as well as incoherent scattering
on atomic electrons to describe the muon scattering at large angles in thick
matter layers. The results of the two methods of calculations are in good
agreement.
