Serratus Anterior

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 Abdomen
Figure 2: Intercostal muscles
Figure 3: Muscles that position the Pectoral Girdle
Figure 4: Muscles that move the humerus
Reading list
  • Trigger points
    • Serratus anterior
    • SA
  • Neuman
  • MMT

Overview

The serratus anterior is a fan-shaped muscle that spans the lateral wall of the thorax. Most of the muscle belly lies deep to the scapula. The serratus inserts on the ribs, creating a sawtooth or “serrated” appearance.

Origin

1-9th ribs

Insertion

  • Superior part: Superior angle of Scapula (costal and dorsal surfaces)
  • Intermediate part: Medial border of Scapula (costal surface)
  • Inferior part: Medial border of Scapula (costal surface), Inferior angle (costal and dorsal surfaces)
Figure 5: Left Scapula (Anterior view)

Nerve

The Serratus Anterior is solely innervated by the Long Thoracic N. (C5, C6, C7)

Action

  • Entire muscle:
    • Draws scapula laterally forward, elevates ribs when shoulders are fixed.
    • Anterolateral movement of the scapula along the ribs.
  • Superior part: Lowers the raised arm by depressing the scapula.
  • Inferior part: Rotates inferior angle of scapula laterally forward (allows elevation of arm above 90°)

The superior and inferior parts of the serratus anterior have antagonistic actions in the vertical plane, which is why when the entire muscle activates, the scapula has no vertical translation.

The serratus anterior functions to stabilize the scapula, which provides proximal stability for the shoulder joint.

Function

The Serratus Anterior (along with the rhomboids) serves to aid in scapular stability during arm elevation

Superior View of the shoulder: You can see how the rhomboids and SA both actively stabilize the scapulothoracic joint by pulling the scapula towards the thoracic wall9

Superior View of the shoulder: You can see how the rhomboids and SA both actively stabilize the scapulothoracic joint by pulling the scapula towards the thoracic wall

Release

Prone release

  • Support the anterior shoulder with one arm
  • Start at the lateral border of the scapula and palpate through to feel the serratus anterior’s origin on ribs 1-9.
  • Press on the muscle on the rib.
  • Do not press between the ribs

Paralysis

Causes:

  • SCI
  • peripheral nerve injury
  • Nerve root?
  • botox?

Serratus anterior paralysis can result in detachment of the scapula from the thorax known as “scapular winging.”

Functional ramifications

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.
Finando D, Finando SJ, Finando D. Trigger Point Therapy for Myofascial Pain: The Practice of Informed Touch. Healing Arts Press; 2005.
4.
Neumann DA, Kelly ER, Kiefer CL, Martens K, Grosz CM. Kinesiology of the Musculoskeletal System: Foundations for Rehabilitation. 3rd ed. Elsevier; 2017.
5.
Weinstock D. NeuroKinetic Therapy: An Innovative Approach to Manual Muscle Testing. North Atlantic Books; 2010.
6.
Jones B. B Project Foundations. b Project; 2025.
7.
Gilroy AM, MacPherson BR, Wikenheiser JC, Voll MM, Wesker K, Schünke M, eds. Atlas of Anatomy. 4th ed. Thieme; 2020.
8.
Gray H. Anatomy of the Human Body. 20th ed. (Lewis WH, ed.). Lea & Febiger; 1918. https://www.bartleby.com/107/
9.
Dutton M. Dutton’s Orthopaedic Examination, Evaluation, and Intervention. 5th ed. McGraw Hill Education; 2020.

Citation

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