Pectoralis Major

Authors

Affiliations

Nate Yomogida, B.S., SPT

Doctor of Physical Therapy

B.S. in Kinesiology

Chloë Kerstein, B.S., SPT

Doctor of Physical Therapy

B.A. in Neuroscience

Figure 1: Muscles of the Abdomen¹

Figure 2: Intercostal muscles¹

Figure 3: Muscles that position the Pectoral Girdle¹

Figure 4: Muscles that move the humerus¹

Reading list

• Pectoralis major and subclavius²
• Neuman³
• Pec major clavicular MMT⁴
• Pec major sternal MMT⁴

Muscle	Origin	Insertion	Innervation	Action
Pectoralis major	Clavicle (medial half) Sternum Costal cartilages 1-6 Rectus sheath (anterior layer)	Humerus (crest of greater tubercle)	Lateral pectoral n. Medial pectoral n. C5 - T1	Entire muscle: Adduction, IR Clavicular & Sternocostal parts: Flexion, Aids in respiration when shoulder is fixed

Origin

• Clavicular part: Clavicle (medial half)⁵
• Sternocostal part: sternum, costal cartilages 1–6⁵
• Abdominal part: rectus sheath (anterior layer)⁵

Note

Manubrium and the aponeurosis of the external oblique are potential originations of the pectoralis major

Figure 5: Left Clavicle (superior view)⁶

Figure 6: Left clavicle (inferior view)⁶

Insertion

Humerus (crest of greater tubercle)⁵

Figure 7: Left Humerus (Anterior view)⁶

Innervation

• Lateral pectoral nerve⁵
• Medial pectoral nerve⁵
• (C5, C6, C7, C8, T1)⁵

Action

• Entire muscle: GHJ Adduction, Internal rotation⁵
• Clavicular and sternocostal parts: Flexion; assist in respiration when shoulder is fixed⁵

Entire muscle: GHJ Adduction, Internal rotation

Clavicular and sternocostal parts: Flexion; assist in respiration when shoulder is fixed

Length test

• PEctoralis major contracture test (hands behind head)

Muscle-to-tendon Surgery

• Worse prognosis than tendon-to-bone because of slow healing

Tendon-to-bone Surgery

considerations

• Thoracic spine mobility
• Grip strength
• light cardio
• contralateral limb training (go light just to be safe to avoid irradiation)

Exercises

• Elbow CARs
• Spine CARs

Strain-Counterstrain

“Location of Tender Point: Anywhere in the clavicular lamina of this muscle. Anatomical Correlation: As stated above. Direction to Press on Tender Point: Press anterior to posterior. Treatment Position(s): With patient supine, sit or stand at the head of the treatment table. Flexion of cervical spine is moderate to marked. Rotation of cervical spine is toward slightly, sidebend toward. The arm on the Tender Point side can be rotated internally, if needed, and pulled medially to further shorten the involved muscle. Frequency of Occurrence: Uncommon. Clinical Correlation(s): Pain in the anterior lateral shoulder which can easily be mistaken for a subacromial bursitis. Associated Pain Referral Pattern: None. Alternate Names/Nomenclatures: None. Explanatory Notes: Note the treatment of depressed 1st and 2nd ribs, which varies from above approach, but is the same muscle.”⁷

References

1.

Betts JG, Blaker W. Anatomy and Physiology. 2nd ed. OpenStax; 2022. https://openstax.org/details/books/anatomy-and-physiology-2e/?Book%20details

2.

Donnelly JM, Simons DG, eds. Travell, Simons & Simons’ Myofascial Pain and Dysfunction: The Trigger Point Manual. Third edition. Wolters Kluwer Health; 2019.

3.

Neumann DA, Kelly ER, Kiefer CL, Martens K, Grosz CM. Kinesiology of the Musculoskeletal System: Foundations for Rehabilitation. 3rd ed. Elsevier; 2017.

4.

Weinstock D. NeuroKinetic Therapy: An Innovative Approach to Manual Muscle Testing. North Atlantic Books; 2010.

5.

Gilroy AM, MacPherson BR, Wikenheiser JC, Voll MM, Wesker K, Schünke M, eds. Atlas of Anatomy. 4th ed. Thieme; 2020.

6.

Gray H. Anatomy of the Human Body. 20th ed. (Lewis WH, ed.). Lea & Febiger; 1918. https://www.bartleby.com/107/

7.

Myers HL, Devine WH, Fossum C, et al. Compendium Edition: Clinical Application of Counterstrain. Compendium ed. Osteopathic Press; 2012.