All of the muscles used for breathing, including the diaphragm, the external intercostal muscles, and the respiratory accessory muscles, are skeletal muscles. Skeletal muscles are controlled by motor nerves of the peripheral nervous system. Motor nerves control motor function, which includes voluntary movement such as walking, speaking, moving an arm, and breathing. Breathing is voluntary, but it is also involuntary.
We can voluntarily control our breathing muscles. We can hold our breath by choosing not to breathe. We can breathe faster or slower, and we can take shallow or deep breaths. At the same time, breathing is also an autonomic action. The brain can automatically regulate how fast and how deeply we breathe without any conscious effort.
Whether breathing is voluntary or involuntary, the nerves that control the muscles used for breathing are motor nerves of the peripheral nervous system. Each of these nerves can be affected by CMT, and as a consequence, the muscles they control, the muscles used for breathing, can become weakened.
