Intercostal Muscles: Definition, Function & Location

Instructor: Alexandra Unfried

Alexandra earned her master's degree in nursing education and is currently a hospital supervisor/administrator.

The human body is made up of many different muscles. Intercostal muscles are found between the ribs. This lesson will discuss what the intercostal muscles are, where they are located, and what they do.

A Dream Deferred

Imagine you are a tennis player, and you finally achieve your lifelong dream of playing in Wimbledon. After warming up for the match, you walk up to the service line to get the match started on your serve. As you toss the ball up, you twist your midsection in order to generate more power, but suddenly you feel a sharp pain around your ribs and immediately begin to wince.

You call the trainer to come over, and you point to the place where you are experiencing pain--directly between your second and third rib on your right side. The trainer is familiar with this type of injury and tells you you have strained your intercostal muscle. You will have to retire and your dreams of winning Wimbledon this year are dashed. As this example shows, an injury to the intercostal muscle can cause severe pain and negatively affect the ability of a person to function. In this lesson, we will learn about what the intercostal muscles are, where they are located, and what they do.

Intercostal Muscles

The intercostal muscles are located in the chest between the ribs. In order to understand more about the intercostal muscles, the ribs must be addressed. There are twelve ribs in the chest. Each of the rib bones is symmetrical on the right and left side of the body. The ribs essentially attach to the sternum and wrap around the chest to the spine. The exception is the eleventh and twelfth rib, which only connects to the spine, not the sternum. The intercostal muscles can be an easily forgotten muscle. It is not a muscle that needs to be exercised or strengthened. However, they are extremely important for survival.

With that being said, there are certain exercises that can make the intercostal muscles sore. Pilates is a type of exercise that focuses heavily on breathing, control, and posture. When done correctly, one will feel the intercostal muscles and remember that they exist. There are twenty-two pairs of intercostal muscles that connect each of the ribs together except for the twelfth rib which is the lowest rib. They are divided into two groups consisting of eleven external intercostal muscles and eleven internal intercostal muscles. There is also a small set of muscles that are called the innermost intercostal muscles. These muscles protect the lungs as well as help control the movement of the chest while breathing.

Anatomy of the ribs

Picture of the intercostal muscles

Function of Intercostal Muscles

Essentially, the intercostal muscles aid in breathing by controlling the movement of the chest. However, the external and internal intercostal muscles each play different roles. The external intercostal muscles help with inhalation when breathing. The muscles contract and shorten which elevates and expands the ribs as lung volume increases. The process of exhaling during regular breathing usually does not involve the internal intercostal muscles. Instead, exhaling is just the external intercostal muscles relaxing.

The internal intercostal muscles are used when exhaling with force. The muscles contract and shorten which bring the ribs closer together as the lungs decrease in size. The innermost intercostal muscles are the weakest of the intercostal muscles and also assist with inhalation when breathing by contracting the muscles. Once again, in the pilates practice, which focuses on breathing and core work, the intercostal muscles are being exercised and pushed. The internal intercostal muscles are engaged in pilates as there is an emphasis on deep breathing, both inhaling and exhaling.

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