Also called: pec minor
The pectoralis minor is a thin triangular muscle beneath the pectoralis major. It arises from ribs three to five and inserts on the coracoid process of the scapula. The medial pectoral nerve supplies it, and it draws the scapula forward and down; with the scapula fixed it can lift the ribs in forced inspiration.
| Origin | External surfaces of the third to fifth ribs near their costal cartilages. |
|---|---|
| Insertion | Medial border and upper surface of the coracoid process of the scapula. |
| Innervation | Medial pectoral nerve (C8-T1), with a contribution from the lateral pectoral nerve. |
| Blood supply | Pectoral branch of the thoracoacromial artery and lateral thoracic artery. |
| Action | Protracts and depresses the scapula; elevates the ribs in forced inspiration when the scapula is fixed. |
3D model: BodyParts3D (CC BY 4.0), adult male reference anatomy. Highlighted structure shown with nearby bones for context.
The pectoralis minor crosses the axillary vessels and brachial plexus. Surgeons divide the axilla into three parts using this muscle as the reference: parts one, two and three lie above, behind and below it.
Tightness of the muscle can alter scapular position and contribute to a forward-rounded shoulder posture.
On the coracoid process of the scapula.
It pulls the scapula forward and down and can raise the ribs in deep breathing.
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