Breathing is a vital function that most people do without ever thinking about it. According to the "Merck Manual," breathing is controlled by the brain. Muscles in the body are necessary to carry out the respiratory process; they allow the lungs adequate air intake and help expel air during exhalation. Several groups of muscles, spanning from the neck to the stomach, are used in breathing.
Diaphragm
The diaphragm is the primary muscle used in breathing. The diaphragm is located in the chest, just underneath the lungs, and functions as a barrier between the chest and the abdomen in addition to its role in breathing. The European Lung Foundation (ELF) explains that the diaphragm flattens out or moves down to allow the lungs to expand when a person draws in air. This large muscle relaxes upon exhalation, when air is expelled from the lungs.
Abdominal Muscles
The abdominal, or stomach, muscles also play a role in breathing, especially during times of physical exertion. According to the "Merck Manual," exhalation, or breathing out, is not always an active process, as is the process of inhalation. However, when a person exerts herself and breathes faster than normal, the abdominal muscles aid in breathing. These muscles are located right underneath the diaphragm.
Intercostal Muscles
A group of muscles called intercostal muscles are located in the chest cavity, between the ribs. Because the lungs do not contain muscles of their own, the intercostal muscles are involved in the respiration process. The intercostal muscles help move the ribcage; when a person inhales, or takes in a breath, the ribs move outward to give the lungs their full capacity.
Neck Muscles
Neck muscles called scalenes are used in breathing on a routine basis. People who have problems with shortness of breath, or suffer from respiratory conditions pertaining to the diaphragm or abdominal muscle weakness may compensate and use more neck muscles when they breathe. The European Lung Foundation explains that when a person has a deficiency in one area of the breathing process, his body may call upon other neck and shoulder muscles to aid in respiration.
