Does Myasthenia Gravis primarily affect voluntary or involuntary muscles?

• A. Voluntary
• B. Involuntary
• C. Cardiac
• D. Smooth

Answer: (A)

Myasthenia Gravis targets the junctions where voluntary skeletal muscles receive nerve signals. It’s an autoimmune attack against nicotinic acetylcholine receptors at the neuromuscular junction of skeletal (voluntary) muscle, so the muscles we consciously control become weak with use and improve with rest. Involuntary muscles—smooth muscles and cardiac muscle—are governed mainly by autonomic nervous system signals and have different receptor systems and junctions, so they are not the primary site of this autoimmune process. That’s why voluntary (skeletal) muscles are the ones most affected in this condition.