The pectoralis minor is a thin, triangular muscle that lies completely underneath the pectoralis major, connecting the front of the upper ribs to the coracoid process of the shoulder blade. Despite its small size, it exerts a powerful influence on scapular position, pulling the coracoid forward and down, which directly affects how well the shoulder blade can rotate upward during overhead movements. It is a key muscle in both shoulder dysfunction assessment and breathing mechanics.
| Origin | Anterior surfaces and superior borders of ribs 3-5 near their costal cartilages |
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| Insertion | Coracoid process of the scapula |
| Nerve Supply | Medial pectoral nerve (C8, T1) |
| Blood Supply | Pectoral branch of thoracoacromial artery |
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Its primary role is to stabilise and depress the scapula against the rib cage, but when shortened or hypertonic it becomes a significant contributor to anterior shoulder tipping, limiting the upward rotation needed for full overhead range of motion.
Pectoralis minor tightness is one of the most important findings in shoulder impingement and scapular dyskinesis, as anterior scapular tipping reduces subacromial space during arm elevation. The brachial plexus and axillary vessels pass beneath it near the coracoid, so a tight or hypertrophied muscle can compress them (pectoralis minor syndrome, a form of thoracic outlet syndrome), with tenderness over the coracoid attachment. Stretching and manual therapy are first-line; resistant cases are treated by releasing the tendon from the coracoid. The tendon is also detached from the coracoid during the Latarjet procedure for shoulder instability.
With the subject supine, slide your fingers under the lower edge of the pectoralis major, angled toward the coracoid process, the pectoralis minor can be felt as a firm cord running diagonally upward. Asking the subject to take a deep breath will cause it to tense slightly.
Compression of the brachial plexus or subclavian vessels beneath a hypertonic pectoralis minor, producing arm pain, paraesthesia, and fatigue with overhead activities, a subset of thoracic outlet syndrome distinguished by tenderness directly over the coracoid attachment.
Muscle fibre tears from sudden forceful protraction or depression of the scapula, presenting as deep anterior chest pain below the clavicle that worsens with reaching forward or deep inspiration.
