What are the intercostal muscles and where are they located in the body?  

Expert Answers
rmhope eNotes educator| Certified Educator

Intercostal muscles are located between the ribs. There are 22 pairs of intercostal muscles: 11 internal pairs and 11 external pairs. Each rib is connected to the rib below it by internal and external intercostals. The exception is the twelfth rib, which is at the bottom of the rib cage. As these muscles expand and contract, the rib cage moves. Thus the muscles allow your lungs to expand within your chest cavity. In addition to these 22 pairs, you have what are known as the innermost intercostals, which lie deep in the chest cavity.

When you inhale, the external intercostals lift and spread the ribs, allowing your lungs to expand. When you exhale, the internal intercostals pull the ribs closer together, helping to force air from the lungs.

Most people don't notice or think about their intercostal muscles. But if you strain one or more of these muscles, it can be quite painful. You might feel a sharp pain every time you breathe in, or you might feel a deep, dull ache when you inhale. Sports, falls, or even housework can cause injury to the intercostal muscles. Anything that produces a sudden jerk to your body, even a powerful sneeze, could result in a strain to the intercostals. Then you would notice the muscles that normally function so quietly in the background.

kc4u | Student

There are several groups of muscles running between the ribs and involved in the mechanical aspect of breathing are called intercostal muscles. These muscles are of two types: internal(inside the ribcase) and external(outside the ribcase).These muscles alternately lift and compress the ribcase to permit respiration. The external intercostal muscles, which aid in quiet and forced inhalation, originate on ribs 1-11 and have their insertion on ribs 2-12. The external intercostals are responsible for the elevation of the ribs, and expanding the transverse dimensions of the thoracic cavity. The internal intercostal muscles, which aid in forced expiration, originate on ribs 2-12 and have their insertions on ribs 1-11.

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