Mitochondrion are the powerhouses of all cells. Obviously, you would need lots of power to move the muscles in your body. Therefore, muscle cells (myocytes) have a relatively large amount of mitochondria in order to provide enough energy to move the muscle, an essential life process.
This article from enotes explain how it interacts with ribosomes.
Its main job is to break down glucose into ATP (energy that the cell can use). The mitochondria does work with other cell organelles in that the ATP is dispersed throughout the cell to power the function of the cell. Specifically, the Ribosomes use the ATP to produce proteins in a process known as protein synthesis.