A muscle biopsy is a medical procedure that involves taking a small sample of muscle tissue for examination. This test helps doctors diagnose various muscle disorders, including inflammatory myopathies, muscular dystrophies, and metabolic muscle diseases. The sample is usually taken from the thigh or arm and can be done using a needle or through a small surgical incision. After the sample is collected, it is sent to a laboratory where it is analyzed under a microscope. The results can provide valuable information about the health of the muscle and help guide treatment options. This procedure is often performed by a specialist, such as a neurologist or rheumatologist.