The primary muscles that cover the ribs are the intercostal muscles.
The intercostal muscles are a group of muscles located between the ribs that play a crucial role in breathing. There are three layers of intercostal muscles:
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External Intercostals: These muscles are primarily involved in inspiration (breathing in). Their fibers run downwards and forwards.
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Internal Intercostals: These muscles assist in expiration (breathing out). Their fibers run downwards and backwards, at right angles to the external intercostals.
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Innermost Intercostals: These muscles are the deepest layer and have a similar function to the internal intercostals, aiding in forced expiration.
In addition to the intercostal muscles, other muscles in the thorax also cover the ribs and contribute to breathing and trunk stability. These include:
- Subcostalis: These muscles span multiple ribs internally, aiding in expiration.
- Transversus Thoracis: Located on the anterior inner wall of the thorax, this muscle helps depress the ribs during forced expiration.
Here is a summary table:
| Muscle | Location | Primary Function |
|---|---|---|
| External Intercostals | Between the ribs | Inspiration (breathing in) |
| Internal Intercostals | Between the ribs | Expiration (breathing out) |
| Innermost Intercostals | Between the ribs | Forced Expiration |
| Subcostalis | Inner rib surface | Expiration |
| Transversus Thoracis | Anterior inner thorax wall | Depresses ribs during expiration |
The intercostal muscles, along with other thoracic muscles, work together to protect the ribs and facilitate respiration.
