Library · Anatomy
Intercostal muscles
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Between one rib and the next there is no empty gap: there is muscle. The chest wall has five muscles, and going from the skin inward they appear in this order: the external intercostal, the internal intercostal, the innermost intercostal, the subcostal at the back and the transversus thoracis at the front.
Their role in breathing is mechanical. They move the ribs, and in moving them they change the volume of the chest cavity, which is the space where the lungs sit.
When they raise the ribs that space grows, and with it vital capacity, that is, the air that can be moved in one full breath. They can also lower them.
Think of slatted blinds linked by strips that draw them together or apart. Between two of those layers, the innermost and the internal, runs the wall's bundle of nerves and vessels.
In brief
The chest wall has five muscles: from superficial to deep, the external intercostal, the internal, the innermost, the subcostal and the transversus thoracis.
They take part in breathing by moving the ribs and changing the volume of the chest cavity.
They raise or lower the ribs; raising them increases chest volume and with it vital capacity.
Slatted blinds linked by strips that draw them together or apart.
The deep neurovascular plane of the wall runs between the innermost and internal intercostals.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingAnatomy, Thorax, StatPearlsPublished
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