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Pectoral Region Muscles Anatomy
Pectoral Region Muscles Anatomy
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The pectoral region is the front part of the chest. It contains four main muscles that move and stabilize the upper limb:
Pectoralis major
Pectoralis minor
Serratus anterior
Subclavius.
These muscles help connect the arm to the chest and play an important role in shoulder and arm movement, as well as in breathing and posture.
Pectoralis Major
Pectoralis Major
The pectoralis major is the largest and most visible chest muscle. It is thick, fan-shaped, and located on the upper front of the chest. It has two main parts (or heads):
Clavicular head: starts from the front of the medial half of the clavicle.
Sternocostal head: starts from the front of the sternum and the first six costal cartilages, plus the external oblique’s aponeurosis.
Both parts attach to the lateral lip of the intertubercular sulcus of the humerus.
The pectoralis major moves the arm toward the body (adduction), rotates the arm inward (medial rotation), pulls the shoulder forward and downward, and its clavicular head flexes the arm; the sternocostal head helps extend it.
Innervation: Lateral and medial pectoral nerves (C5–T1).
Pectoralis Minor
Pectoralis Minor
The pectoralis minor is a thin, triangular muscle that lies beneath the pectoralis major. It helps stabilize and move the shoulder blade (scapula).
The pectoralis minor pulls the scapula forward and downward against the chest wall and helps lift the ribs during deep inhalation.
Origin: Front surfaces of ribs 3–5 near their costal cartilages.
Insertion: Coracoid process of the scapula.
Innervation: Medial pectoral nerve (C8–T1).
Quick Reference Table: Muscle Name, Origin, Insertion & Innervation
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Serratus Anterior
Serratus Anterior
The serratus anterior is a large, fan-shaped muscle on the side of the chest. It sits between the ribs and the scapula and is often visible under the arm in athletic individuals.
The serratus anterior rotates the scapula upward, allowing the arm to lift above 90°, pulls the scapula forward (protraction) and keeps it against the ribcage (prevents “winging”), and assists in breathing when the shoulder is fixed.
Origin: Outer surfaces of ribs 1–8 (sometimes 1–9).
Insertion: Inner (costal) surface of the medial border of the scapula.
Innervation: Long thoracic nerve (C5–C7).
Subclavius
Subclavius
The subclavius is a small, narrow muscle located just below the clavicle. It helps stabilize the clavicle and protects nearby blood vessels and nerves.
The subclavius anchors and lowers the clavicle, stabilizes the clavicle during shoulder movement, and provides protection for the subclavian vessels and brachial plexus.
Origin: Junction between the first rib and its costal cartilage.
Insertion: Underside (inferior surface) of the middle third of the clavicle.
Innervation: Nerve to subclavius (C5–C6).
Need a recap? Take a look at the Pectoral Region Muscles anatomy notes here.
Need a recap? Take a look at the Pectoral Region Muscles anatomy notes here.
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References
References
Gray, H. (2009). Anatomy of the human body, part 2 (LibriVox Volunteers, Narr.) [Audiobook]. LibriVox. https://librivox.org/anatomy-of-the-human-body-part-2-by-henry-gray/ (Original work published 1858)
J Gordon Betts, Desaix, P., Johnson, E., Johnson, J. E., Korol, O., Kruse, D., Poe, B., Wise, J., Womble, M. D., & Young, K. A. (2013). Anatomy & physiology. Openstax College, Rice University. https://openstax.org/details/books/anatomy-and-physiology
Based on OpenStax, Anatomy and Physiology (2013), licensed under CC BY 4.0.
Access for free at https://openstax.org/books/anatomy-and-physiology/pages/1-introduction.
Content paraphrased; adaptations were made.
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