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Latissimus Dorsi Origin, Insertion, Action, Innervation

(Last Updated On: August 10, 2018)
Latissimus Dorsi Origin, Insertion, Action, Innervation

Muscle Anatomy of the Latissimus Dorsi

Origin: Spinous processes of thoracic T7-T12, 9th to 12th ribs, the lumbar and sacral vertebrae (via the thoracolumbar fascia), and the posterior third of the external lip of the iliac crest. Occasionally by a slip from the posterior surface of the inferior angle of the scapula.
Insertion: Ends as a flattened tendon in front of the attachment of teres major to the floor of the bicipital groove of the humerus
Actions: Adducts, extends and internally rotates the arm at the shoulder
Innervation: Thoracodorsal nerve (C6 – C8)
Blood Supply: Thoracordosal Artery from the axillary artery

Muscle Anatomy: Latissimus Dorsi Actions

Primary Actions of the Latissimus Dorsi

1.  Adduction of the arm at shoulder

  Agonists:

  • Pectoralis Major
  • Teres Major
  • Triceps Brachii (long head)

  Antagonists:

  • Deltoid (middle)
  • Supraspinatus

2. Extension of the arm at the shoulder

  Angonists:

  • Deltoid (posterior)
  • Triceps brachii (long head)
  • Pectoralis major (sternal head)

  Antagonists:

  • Deltoid (anterior)
  • Biceps brachii
  • Coracobrachialis
  • Pectorial Major (clavicular head)

3. Internal rotation of the arm at the shoulder

  Agonists:

  • Subscapularis
  • Deltoid (anterior)
  • Pectoralis major
  • Teres major

  Antagonists:

  • Infraspinatus
  • Teres minor
  • Deltoid (posterior)

Secondary Actions of the Latissimus Dorsi:

1. Assists with extension of the trunk

  Agonists:

  • Longissimus thoracis
  • Iliocostalis lumborum
  • Iliocostalis thoracis

  Antagonists: 

  • Rectus abdominis

2. Assists with flexion of the trunk

  Agonist:

  • Rectus abdominis

  Antagonists:

  • Longissimus thoracis
  • Iliocostalis lumborum
  • Iliocostalis thoracis

3. Assists with lateral flexion of the trunk

  Agonist:

  • Quadratus lumborum
  • Rectus abdominis

  Antagonists:

  • Longissimus thoracis
  • Iliocostalis lumborum
  • Iliocostalis thoracis

4. Assists with anterior and lateral pelvic tilt

  Agonist: 

  • Rectus abdominis

  Antagonists:

  • Semitendinosus
  • Semimembranosus
  • Biceps femoris

5. Assists with depression of the scapula

  Agonists:

  • Serratus Anterior (lower fibers)
  • Trapezius (lower fibers)
  • Pectoralis minor

  Antagonists:

  • Levator scapulae
  • Trapezius (upper fibers)

6. Assist with protraction of the scapula

7. Assists with deep inspiration and forced expiration

 

Information about cause and effect of Latissimus Dorsi pain:

 

 Latissimus Dorsi Muscle: Shoulder, Arm, Low Abdominal, Pain 

Recommended Anatomy Books:

Anatomy Coloring Book

The Anatomy Coloring Book is one of the best study and reference books for beginning anatomy students. The diagrams are clearly labeled and allow you to see the relationship and placement of the various structures of the body. You will also be surprised how the act of coloring will help with recall. But this is not just a beginners book, it is also great for practitioners and therapists to have on hand to use with clients and patients to use as a visual reference.

Human Muscle Anatomy

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!

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.

Muscle Anatomy Flashcards

Musculoskeletal Anatomy 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.

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