Résumé : Results are presented from a search for heavy, right-handed muon neutrinos, Nμ, and right-handed WR bosons, which arise in the left-right symmetric extensions of the standard model. The analysis is based on a 5.0 fb-1 sample of proton-proton collisions at a center-of-mass energy of 7 TeV, collected by the CMS detector at the Large Hadron Collider. No evidence is observed for an excess of events over the standard model expectation. For models with exact left-right symmetry, heavy right-handed neutrinos are excluded at 95% confidence level for a range of neutrino masses below the WR mass, dependent on the value of MWR. The excluded region in the two-dimensional (MWR, MNμ) mass plane extends to MWR=2.5 TeV.