Air is pulled into the lungs by the diaphragm and intercostal muscles. Extra muscles such as those in the neck can be recruited when necessary.

Breathing is accomplished with the effort of respiratory muscles. A dome-shaped muscle called the diaphragm, located below the lungs, and muscles between the ribs called the intercostals, pull air into the lungs. This inspiration, or inhalation, is followed by a relaxation of these muscles as air leaves the lungs.

The process of breathing in and out, taking in oxygen and exhaling carbon dioxide, is called air (or gas) exchange, or ventilation. The pathway that air follows from the nose, through the trachea and into the lungs is the airway.

Researchers are investigating the possible value of electronically stimulating the phrenic nerve, which controls the diaphragm, in assisting breathing in ALS.

When you forcefully inhale or exhale, you use extra, or accessory, muscles of breathing. Accessory respiratory muscles include those in the abdomen, chest wall and neck.

Over time, neuromuscular disorders can weaken all of these muscles. When these muscles don’t move, air can’t move in and out of the lungs effectively.

Respiratory failure, often in association with an infection (pneumonia), is a frequent cause of death for people with neuromuscular disorders.

Sometimes a decline in respiratory function can be so gradual that it isn’t noticed at all or is attributed to some other cause, such as general fatigue, depression or sleep problems.

In this booklet, you’ll learn that monitoring your breathing function isn’t harder than any other type of monitoring; and that with good health care, therapeutic techniques and supportive equipment, you can prolong breathing function for years and avoid having a respiratory crisis.