Latissimus Dorsi Muscle

Latissimus Dorsi Muscle

Origin: Spinous processes of vertebrae T7-T12, Thoracolumbar fascia, Posterior third of crest of ilium, Ribs 9-12, Inferior angle of scapula
Insertion: Intertubercular groove of the humerus
Actions: Adducts, extends and internal rotation of the arm at the shoulder
Innervation: Thoracodorsal nerve (C6 – C8)
Blood Supply: Thoracodorsal artery from the axillary artery

Primary Actions of the Latissimus Dorsi Muscle

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

  Agonists:

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

  Antagonists:

  • Deltoid (anterior)
  • Biceps brachii
  • Coracobrachialis
  • Pectoralis 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

  Agonists:

  • Rectus Abdominis

  Antagonists:

  • Longissimus thoracis
  • Iliocostalis lumborum
  • Iliocostalis thoracis

3. Assists with lateral flexion of the trunk

  Agonists:

  • Quadratus lumborum
  • Rectus abdominis

  Antagonists:

  • Longissimus thoracis
  • Iliocostalis lumborum
  • Iliocostalis thoracis

4. Assists with anterior and lateral pelvic tilt

  Agonists:

  • Rectus abdominis

  Antagonists:

  • Semitendinosus
  • Semimembranosus
  • Biceps femoris

5. Assists with depression of the scapula

  Agonists:

  • Serratus anterior (lower part)
  • Trapezius (lower part)
  • Pectoralis minor

  Antagonists:

  • Levator scapulae
  • Trapezius (upper part)

6. Assists with protraction of the scapula

7. Assists with deep inspiration and forced expiration

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Muscle Pain Information: The latissimus dorsi muscle contributes to pain middle and lower back and the front of the shoulder. It refers pain to the inside of the upper arm that descends into the elbow, wrist, hand, and into the little finger.

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