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Sternocleidomastoid Anatomy: Origin, Insertion, Action, Innervation

Sternocleidomastoid Anatomy Study

Sternocleidomastoid Anatomy

Sternal Head:

Origin:  Upper part of the anterior surface of the manubrium

Clavicular Head:

Origin: Superior surface of the medial one third of clavicle
Insertion: Lateral surface of the mastoid process of the occipital bone, from its apex to its superior border, and by a thin aponeurosis to the lateral half of the superior nuchal line
Action: Bilaterally: flexion of the head and neck, extension of the head and neck
Unilaterally: rotation of head to opposite side, lateral flexion
Accessory nerve: cranial nerve XII and ventral rami of the (C2, C3)

Blood Supply: Branches from the vertebral artery

Synergist: Trapezius, Semispinalis capitis, Rectus capitis, Oblique capitis superior, Splenius capitis, Longissimus capitis

Antagonist: Longus capitis, Rectus capitis

For pain and symptom information see: Sternocleidomastoid Muscles: Affects Head, Eyes, Sinus, Ears, Throat, Pain, Dizziness, Whiplash



Primary Actions of the Sternocleidomastiod:

1. Extension of the head and cervical spine when posterior fibers act bilaterally

  • Agonists: Longissimus Capitis, Spinalis Capitis, Splenius Capitis, Semispinalis Capitis
  • Antagonists: Longus Capitis, Sternocleidomastoid (anterior fibers

2. Flexion of the head and cervical spine when anterior fibers act bilaterally

  • Agonists: Longus Capitis
  • Antagonists: Longissimus Capitis, Spinalis Capitis, Splenius Capitis, Semispinalis Capitis, Sternocleidomastoid (posterior fibers)

3. Lateral flexion of the head and cervical spine when acting unilaterally

  • Agonists: Splenius Capitis
  • Antagonists: Same muscles on opposite side (Splenius Capitis)

4. Contralateral rotation of the head and cervical spine when acting unilaterally

  • Agonists: Semispinalis Capitis
  • Antagonists: Splenius Capitis on opposite side

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.

Trail Guide To The Body

Trail Guide To The Body


The Trail Guide To The Body is another excellent book to help you learn the musculature of the human body. Though the book is geared toward massage therapists and physical therapist assistants, the book with its illustrations and text helps anyone gain a thorough understanding of the human musculoskeletal system and movement. I highly recommend this book for anyone studying anatomy and believe that MTs, PTAs, and teachers of body movements should have this book in their possession. I also highly recommend this book for the lay person who wants to gain understanding of the muscle, skeletal system and how our bodies move. This book will not disappoint!



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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