Latissimus Dorsi

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: Left Humerus (Anterior view)
Figure 2: Muscles of the Abdomen
Figure 3: Muscles that move the humerus
Reading list
  • Straight arm MMT
  • Bent arm MMT

Origin

  • Vertebral part: Spinous processes of T7–T12 vertebrae; thoracolumbar fascia
  • Scapular part: Scapula (inferior angle)
  • Costal part: 9th to 12th ribs
  • Iliac part: Iliac crest (posterior one third)

Insertion

Floor of intertubercular groove of humerus

Innervation

Thoracodorsal n. (C6, C7, C8)

Action

  • GHJ: Internal rotation, adduction, extension

  • Respiration: “cough muscle”

  • Biomechanics

    • Isolated Latissimus dorsi contraction results in inferior displacement of the humeral head
Adductor force couple

The triceps brachii long head and latissimus dorsi form a “force adductor couple”. The adduction and extension moment created by the latissimus dorsi results in inferior displacement of the humeral head, the triceps long head contracts and its abductive component counteracts the latissimus dorsi creating a superior glide. This results in no net vertical translation of the humeral head and keeping its optimal position in the glenoid.

Thus although the triceps long head has an “abductive” component, we consider it to function as an “adductive assist.”

Function

This muscle adducts and internally rotates the arm and depresses the raised arm

Mini lat muscle

The teres major can almost be considered a “mini lat” since it has the same functions

References

1.
Gray H. Anatomy of the Human Body. 20th ed. (Lewis WH, ed.). Lea & Febiger; 1918. https://www.bartleby.com/107/
2.
Betts JG, Blaker W. Anatomy and Physiology. 2nd ed. OpenStax; 2022. https://openstax.org/details/books/anatomy-and-physiology-2e/?Book%20details
3.
Weinstock D. NeuroKinetic Therapy: An Innovative Approach to Manual Muscle Testing. North Atlantic Books; 2010.
4.
Gilroy AM, MacPherson BR, Wikenheiser JC, Voll MM, Wesker K, Schünke M, eds. Atlas of Anatomy. 4th ed. Thieme; 2020.
5.
Jones B. B Project Foundations. b Project; 2025.
6.
Brazis PW, Masdeu JC, Biller J. Localization in Clinical Neurology. 8th ed. Wolters Kluwer Health; 2022.

Citation

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