The Musculi intercostales is a special muscle in the human body. The intercostal muscles belong to the so-called autochthonous chest muscles.

They are composed of different muscle parts, which together play an important role in breathing. The most important elements of the intercostal muscles are the internal intercostal muscles, the external intercostal muscles and the intercostal intimal muscles.

What are the intercostal muscles?

Essentially, the intercostal muscles are composed of three components. These parts are separate muscle parts, but they are intimately connected and interact in different tasks and movements of the body. These include, on the one hand, the internal intercostal muscles, which belong to the autochthonous chest muscles.

The internal intercostal muscles represent a very deep layer within the intercostal musculature. They are covered in all intercostal spaces by the intercostal externi muscles. Similarly, the intercostal externi muscles are an element of the autochthonous chest muscles. The intercostal externi muscles are located on the surface of the intercostal muscles, thus forming their upper level or layer. Finally, the intercostal intimal muscles belong to the so-called skeletal muscles and are also part of the intercostal musculature.

Anatomy & Construction

The intercostal interni muscles and the intercostal externi muscles are the so-called intercostal muscles. The internal intercostal muscles form the internal intercostal muscles, while the intercostal external muscles constitute the external intercostal muscles.

The intercostal interni muscles are from the upper margins of the second to twelfth ribs. The areas of origin of this type of muscle range from the end of the cartilage of the ribs, which is located on the so-called sternum, to the Angulus costae. The internal intercostal muscles are oblique. Thus, the intercostal muscles attach to the lower edge of the overlying rib. Basically, the fibers of these muscles run in the same direction as the fibers of the so-called Musculus obliquus internus abdominis.

Near the border between bone and cartilage and Angulus costae, the intercostal nerves separate the internal intercostal muscles from the intercostal intimal muscles. The innervation of this muscle part takes place through the intercostal nerves from special areas of the spinal cord.

The Musculi intercostales externi have their origin in the lower edge of the first to eleventh rib. The area of ​​their origin extends from the tuberculum costae to the transition between cartilage and bone. Between the cartilages of the ribs, the intercostal muscles find their equivalent in the so-called Membrana intercostalis externa. Like the intercostal interni muscles, the intercostal externi muscles also run obliquely. Their course corresponds to that of the external oblique muscle abdominis. The intercostal externi muscles attach to the upper margins of the second to twelfth ribs. The intercostal externi muscles are innervated by the intercostal nerve.

Musculi intercostales intimi is a deep-lying muscle layer of the internal intercostal muscles. The intercostal intimal muscles separate from the internal intercostal muscles in the area between the angulus costae and the transition between bone and cartilage. The separation between the two muscle parts represents the corresponding intercostal nerve and the respective intercostal artery. The intercostal intimal muscles are innervated by the intercostal nerve. In detail, the innervation is segmental from certain areas of the spinal cord.

Function & Tasks

The intercostal muscles perform various important tasks and functions in the muscular system. They play an important role primarily in connection with the respiratory muscles. The internal intercostal muscles are respiratory muscles responsible for exhalation (medical term expiration). By tensing the respective intercostal space, the ribs are lowered. As a result, the volume of the bony part of the thorax is reduced.

In the same way the muscles intercostales externi count to the respiratory musculature. They are in a sense the antagonist to the intercostal interni muscles, because they are responsible for the inspiration (medical term inspiration). In conjunction with contractions, they span the corresponding area of ​​the intercostal space. In this way they cause an increase in the volume in the bony thorax. The Musculi intercostales intimi are so-called Rippensenker, which also participate in the exhalation.


In connection with the intercostal muscles, various diseases and complaints are possible which sometimes limit the quality of life of the affected patients and in some cases even lead to life-threatening conditions.

Since the intercostal muscles play an important role in breathing, impairments in the functioning of the muscles are correspondingly serious. For the respiratory processes depend on the smooth functioning of the intercostal muscles. Disorders of the intercostal interni muscles cause exhalation problems, while complications of the intercostal external muscles interfere with inhalation.

For this reason, complaints to the intercostal muscles should be presented as quickly as possible to a doctor, so that adequate treatment of the symptoms and the underlying disease can be started immediately. As a person relies continuously on functioning breathing, associated complaints are to be taken seriously.

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