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The Use of Accessory Muscles With Breathing

author image Meg Brannagan
Meg Brannagan has worked as a registered nurse for more than 10 years, specializing in women's and children's health. She holds a bachelor's degree in nursing from the University of Nebraska Medical Center.
The Use of Accessory Muscles With Breathing
Using accessory muscles while breathing indicates a problem. Photo Credit Jupiterimages/Goodshoot/Getty Images
Medically Reviewed by
George Krucik, MD, MBA

Most people breathe without thinking about how to do it. Inadequate oxygen can cause a person to work harder to breathe, requiring the use of accessory muscles. Using these muscles indicates a potential injury or disease process that is affecting a person’s ability to breathe.


Respiration is necessary to provide oxygen for all of the tissues in the body. When a person inhales through the mouth or nose, oxygenated air travels into the body past the pharynx, through the trachea, and into the lungs. Carbon dioxide is then released out of the body through exhalation. The diaphragm is a large muscle found below the lungs, which separates the chest compartment from the abdomen. The diaphragm is responsible for controlling the actions of breathing in and out.


Accessory muscles are used in addition to the diaphragm for breathing, but this is not normal. Accessory muscles used for inhalation include the scalene, sternomastoid and trapezium, which are found around the shoulders and neck. If a person feels he is having difficulty getting enough oxygen, his body begins to clench these muscles every time he breathes in as an attempt to acquire more air.


Accessory muscles may also be used when a person exhales. According to Loyola University Health System, typical exhalation is a passive act that occurs naturally without using any muscles. A person may begin to use accessory muscles while breathing out if he feels he is retaining air within the lungs. This is known as forced expiration, and it uses accessory muscles in the abdomen and the chest.


Inspiratory accessory muscles might be used with certain conditions such as pneumonia, an allergic reaction causing anaphylaxis, an asthma attack or an obstruction that does not allow adequate air to pass. Accessory muscles are used with exhalation by many people who have chronic obstructive pulmonary disease (COPD). Over time COPD causes changes within a person’s lungs, resulting in air trapping. This leaves a feeling of fullness in the lungs, and a person may work harder to expel air.


In order to reduce the use of accessory muscles, the underlying cause must be treated. Inspiratory accessory muscles are typically used with decreased air movement upon inhalation. The underlying disorder then needs treatment, such as using a bronchodilator for an asthma attack; treating pneumonia with antibiotics; or removing an obstruction. For persons who use expiratory accessory muscles, a breathing technique known as pursed lip breathing can be employed. According to the Pulmonary Education and Research Foundation, pursed lip breathing is a method of slowly breathing in through the nose and blowing out air through the mouth. The method is taught to patients with COPD to help them slow down and concentrate on their breathing. The result is increased levels of oxygen in the bloodstream, requiring less use of accessory muscles.

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