Intercostal muscles

Muscles located between the ribs that play a vital role in breathing.

Intercostal muscles are a group of muscles situated between the ribs, comprising three main layers: external, internal, and innermost. These muscles are essential for the mechanics of breathing as they assist in expanding and contracting the rib cage during respiration.

Terminologia Anatomica

musculi intercostales

System

Respiratory system

Function

The primary role of intercostal muscles lies in the process of respiration. When inhaling, the external intercostal muscles contract, lifting the rib cage and allowing the lungs to expand and fill with air. This action also creates negative pressure within the thoracic cavity. During exhalation, particularly active exhalation, such as during physical exertion, the internal intercostal muscles contract, pulling the rib cage downwards and internally, which helps to expel air from the lungs. Thus, the intercostal muscles ensure that the process of breathing is efficient and effective, enabling oxygen intake and carbon dioxide expulsion.

Location

Intercostal muscles are located in the thoracic region, specifically between each rib of the rib cage. The external intercostal muscles are the outermost layer, starting from the lower border of one rib and extending to the upper border of the rib below. Beneath them lie the internal intercostal muscles, which run in the opposite direction, and the innermost intercostal muscles are found deep to the internal ones. The regions they occupy span the entire length of the rib cage, allowing them to effectively assist in respiratory movements during the inhalation and exhalation phases.

Did You Know?

Intercostal muscles work in conjunction with the diaphragm, which is the primary muscle responsible for breathing.
During intense physical activity, intercostal muscles are engaged more significantly to facilitate rapid and deeper breathing.
In addition to breathing, intercostal muscles play a role in stabilizing the chest wall during movements and postural adjustments.