The course of the "Petite rivière Muskrat" crosses the territory of the municipality of Adstock, in the Les Appalaches Regional County Municipality, in the administrative region of Chaudière-Appalaches, on the South Shore of the St. Lawrence River, in Quebec, Canada.

This zone is located almost at the eastern limit of the Les Appalaches Regional County Municipality (MRC) and Beauce-Sartigan.

From its head, the Petite rivière Muskrat flows on 3.9 kilometres (2.4 mi) towards the southwest, passing south of lakes Rochu and Bolduc, to the limit of Parc national de Frontenac; on 2.1 kilometres (1.3 mi) towards the north-west leaving the Park, up to a small stream (coming from the east); on 3.2 kilometres (2.0 mi) westward crossing the park boundary to its mouth, located near a road bridge that spans the small bay.

[1] The mouth of the "Little Muskrat River" empties into a marsh area at the bottom of the "Baie aux Rats Musqués" which is an extension of the northeast shore of Grand lac Saint François.

The toponym "Petite rivière Muskrat" was officially registered on August 4, 1969, at the Commission de toponymie du Québec.