| Latin | Musculi intercostales |
|---|---|
| Origin |
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| Insertion |
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| Action |
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| Nerve | Intercostal nerves (T1–T11) |
| Name | Latin inter, 'between', and costa, 'rib' — the muscles between the ribs. |
Palpation
- Client side-lying with the top arm resting forward on a pillow to open the ribs, or supine.
- Place the pads of two fingers on the side of the chest below the armpit, and find a rib, then the soft groove just below it.
- Follow the groove (the intercostal space) with light pressure; the external intercostals run downwards and forwards in the same direction as the external oblique.
- Ask the client to take a slow, deep breath in; feel the ribs lift and the space widen under your fingers.
The intercostals are three layers of muscle between each pair of ribs. The external intercostals are the outer layer; their fibres run downwards and forwards (like the External oblique) and help the Diaphragm lift and widen the ribcage on the in-breath. The internal intercostals run at right angles to them and help pull the ribs down for a forced out-breath. The thin innermost intercostals lie deepest, separated from the internal layer by the intercostal nerve and blood vessels, and are thought to act with the internal intercostals. Because the layers work in opposite directions, the group has no single antagonist.
For massage, the intercostals matter mainly for breathing and relaxation. A ribcage that moves freely makes slow, deep breathing easier. Gentle strokes along the rib spaces (from the sternum out to the side, or from the spine out to the side when the client is prone), followed by a still hand resting on the ribs while the client breathes, can help clients notice and slow their breathing. Many clients report this feels calming (see Relaxation and the parasympathetic response).
Use light, flat pressure and keep your fingers in the soft spaces, not on the rib edges. Avoid breast tissue and follow draping and consent guidance in Abdomen and chest — 15 min. Sources give fibre directions and actions consistently; the role of the innermost layer is the least well described.