Muscle biopsies can also help to distinguish among various types of myopathies, by microscopic analysis for differing characteristics when exposed to a variety of chemical reactions and stains.

[1][2] However, in some cases the muscle biopsy alone is inadequate to distinguish between certain myopathies.

For example, a muscle biopsy showing the nucleus pathologically located in the center of the muscle cell would indicate "centronuclear myopathy", but research has shown that a variety of myopathies can cause these centronuclear biopsy appearance, and hence the specific genetic testing becomes increasingly important.

A biopsy needle is usually inserted into a muscle, wherein a small amount of tissue remains.

Alternatively, an "open biopsy" can be performed by obtaining the muscle tissue through a small surgical incision.