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| Latin | Musculus pectoralis minor |
|---|---|
| Origin |
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| Insertion |
|
| Action |
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| Nerve | Medial pectoral nerve (C8–T1) |
| Name | Latin pectus, 'chest', and minor, 'smaller'. |
Palpation
- Client supine with the arm resting by the side; soften pec major by supporting the arm slightly across the body.
- Find the coracoid process just below the lateral clavicle, then slide your fingers down and in towards ribs 3–5.
- Press slowly through pectoralis major, or slide the finger pads under its lateral edge from the armpit, to feel thin, diagonal bands.
- Ask the client to push the shoulder down and forwards towards the table edge against light resistance; feel the fibres tighten.
Pectoralis minor lies under Pectoralis major and connects the ribs to the Coracoid process. When it is short and tight the shoulder is pulled forward and down, a posture clients who sit a lot often show. It works against the middle and lower Trapezius and the rhomboids, which pull the scapula back.
Sources differ slightly. Wikipedia gives an origin on ribs 3–5 but notes it can arise from ribs 2–4 or 2–5 instead. Its muscle article lists only C8 for the nerve root, while its medial pectoral nerve article gives C8–T1. The main nerves and blood vessels to the arm pass directly under this muscle, so use gentle pressure and stop if the client feels tingling in the arm.