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Pectoralis major

Musculus pectoralis major

A fan-shaped muscle of the anterior chest wall, the pectoralis major acts as a powerful adductor, flexor, and medial rotator of the arm at the shoulder, and is essential to pushing movements, climbing, and arm-swinging activities. It is built from a clavicular head and a sternocostal head, which arise respectively from the clavicle and from the sternum and upper costal cartilages; their fibers converge to insert on the lateral lip of the intertubercular sulcus of the humerus. Rupture of the muscle characteristically occurs during heavy bench pressing, and Poland syndrome involves its congenital absence. In reconstructive surgery, the pectoralis major supplies a muscle flap for chest wall repair.

A large, fan-shaped muscle of the anterior chest wall. It has clavicular and sternocostal heads originating from the clavicle, sternum, and upper costal cartilages. The fibers converge to insert on the lateral lip of the intertubercular sulcus of the humerus.

On this page
Type Muscle
Body System Muscular
Body Region Thorax
Parent Structure muscle of shoulder
Latin Name Musculus pectoralis major
FMA ID 9627

Function

A powerful adductor, flexor, and medial rotator of the arm at the shoulder. Essential for pushing movements, climbing, and arm-swinging activities.

Clinical Significance

Pectoralis major rupture occurs during heavy bench pressing. Poland syndrome involves congenital absence of the pectoralis major. The muscle is used in pectoralis major flap reconstructive surgery.

Frequently Asked Questions

What are the primary actions of the pectoralis major?

The pectoralis major is a powerful chest muscle with three actions: adduction of the arm (bringing it toward the body's midline), flexion of the arm at the shoulder, and medial rotation of the humerus. It is most active during pushing movements such as bench pressing, as well as climbing and arm-swinging during running. The clavicular head contributes more to flexion, while the sternocostal head is more active in extension from a flexed position.

What is Poland syndrome?

Poland syndrome is a rare congenital condition characterized by the absence or underdevelopment of the pectoralis major muscle on one side of the body, typically the right. It is often associated with ipsilateral hand abnormalities including shortened fingers (brachydactyly) or webbed fingers (syndactyly). The condition varies widely in severity and may also involve absence of the pectoralis minor and other chest wall structures.

How does pectoralis major rupture occur and how is it recognized?

Pectoralis major rupture most commonly occurs during heavy bench pressing when the muscle is under eccentric load at full stretch. It typically involves the tendon at its humeral insertion. Patients experience sudden sharp chest and arm pain, followed by bruising, swelling, and a visible or palpable defect in the anterior axillary fold. The anterior chest wall contour becomes asymmetric, and there is weakness in arm adduction and internal rotation.

What is the pectoralis major myocutaneous flap?

The pectoralis major myocutaneous flap is a reconstructive surgical technique in which the pectoralis major muscle, along with its overlying skin and subcutaneous tissue, is used to fill tissue defects—most commonly after head and neck cancer resections such as laryngectomy or mandibulectomy. Its robust blood supply from the thoracoacromial artery makes it a reliable flap for covering large wounds or reconstructing the oral cavity and pharynx.

Where does the pectoralis major insert on the humerus?

The pectoralis major inserts on the lateral lip of the bicipital groove of the humerus (also called the intertubercular sulcus). This insertion point allows the muscle to adduct and medially rotate the arm. The fibers twist 180 degrees before insertion, so the lower fibers of the sternal head end up above the upper fibers at the tendon—a design that increases the range over which the muscle can generate force.

References

  1. Foundational Model of Anatomy — FMA:9627 Reference anatomy ontology (University of Washington)
  2. UBERON — UBERON:0002381 Cross-species anatomy ontology (EMBL-EBI Ontology Lookup Service)
  3. Wikipedia — Pectoralis major Encyclopedia article (verified cross-reference)

Medical Disclaimer

This content is for educational and informational purposes only. It is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.

Educational Disclaimer

This content is for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider for medical decisions.

Data sources: Terminologia Anatomica, Foundational Model of Anatomy, Wikidata.