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Serratus Posterior Inferior Muscle Anatomy: Origin, Insertion, Actions, Innervation

Serratus Posterior Inferior Muscle Anatomy Study

Serratus Posterior Inferior Muscle
Origin: The spinous processes of the T11 to L2/L3 and their corresponding supraspinous ligaments, blending with the lumbar part of the thoracolumbar fascia.
Insertion: Inferior borders and outer surfaces of the lower four ribs (9th -12th), lateral to their angles
Action: Depresses the lower ribs aiding in expiration, Assists in rotation and extension of the trunk
Innervation: Ventral primary rami of T9 – T12 (intercostal and subcostal nerves).
Blood Supply: Dorsal branches of the subcostal arteries.

Synergist: Iliocostalis thoracis, Longissimus thoracis, Quadratus lumborum

Primary Action of the Serratus Posterior Inferior Muscle:

1. Forced expiration

  • Agonists: Transversus abdominis
  • Antagonists: Serratus posterior superior, Levatores costarum brevis and longi

Recommended Anatomy Study Aids

Musculoskeletal Anatomy Flashcards

Musculoskeletal Anatomy Flashcards Musculoskeletal Flashcards Are you a student or professional therapist who needs to brush up on the musculoskeletal system? Dr. Joseph E. Muscolino DC has developed a comprehensive set of flashcards that will help develop a mind’s picture of exactly where the muscles lie under the skin. A highly recommended study aid for students. Great for non students who want an easy comprehensive anatomy guide.

Basic Clinical Massage Therapy


Out of the scores of books in my office Basic Clinical Massage Therapy is by far the most referenced book in my library. The musculoskeletal system is overlaid on human models allowing you to learn the precise location, origin and insertions of each muscle. The models are pictured in various poses throughout the book which also helps you visualize muscles in motion and their actions relationship with the skeletal structure and other muscles. Though it is written for massage therapists, it is an excellent book for anyone who wants to learn about the muscular system. MT’s will benefit from recommended treatments for each muscle.



The Trigger Point Therapy Workbook – Claire Davies, Amber Davies, and David G. Simons

Basic Clinical Massage Therapy: Integrating Anatomy and Treatment – James H. Clay and David M. Pounds

Trigger Point Therapy for Myofascial Pain – Donna Finando and Steven Finando

Massage Therapy Principles and Practice – Susan Salvo

Theory & Practice of Therapeutic Massage – Mark Beck


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