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| Latin | Musculus serratus anterior |
|---|---|
| Origin |
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| Insertion |
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| Action |
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| Nerve | Long thoracic nerve (C5–C7) |
| Name | Latin serratus, 'saw-toothed' — its slips on the ribs look like the teeth of a saw. |
Palpation
- Client side-lying with the top arm resting forward on a pillow, or supine with the arm raised.
- Place your finger pads on the side of the ribcage below the armpit, between latissimus dorsi behind and pectoralis major in front.
- Feel the slips as small, diagonal ridges lying over the ribs.
- Ask the client to reach forward, pushing the hand away from the body (like a punch), against light resistance; the slips firm up under your fingers.
Serratus anterior wraps around the side of the ribcage and passes under the scapula to attach along its Medial border of scapula. It is often called the “boxer’s muscle” because it pushes the scapula forward during a punch. It works with the upper and lower Trapezius to rotate the scapula upwards, so the arm can be raised overhead. Its main antagonists are the rhomboids, such as Rhomboid major, which pull the scapula back towards the spine.
Sources differ on the origin: Wikipedia gives ribs 1–9, while some anatomy texts give ribs 1–8. The side of the ribcage can be ticklish, so use a broad, firm touch. The best access is side-lying, where you can work between Latissimus dorsi and Pectoralis major.