A sector of a sectorized annular nozzle of a turbine of a turbomachine comprises an outer platform having an outer wall connected to a coaxial inner wall via at least one straightening fixed blade. The outer platform includes hooking means that hook the outer platform to a turbine fixed casing. The outer platform includes an outer circular shell, axially offset with respect to the outer wall and integrally formed with the outer wall, and the outer shell is intended to surround an angular portion of a rotor wheel. The hooking means includes an upstream circular edge and a downstream circular edge extending axially, said upstream and downstream edges being respectively configured to attach to an upstream hook and a downstream hook of said turbine casing, and said upstream and downstream edges being oriented in the downstream direction.