Latissimus Dorsi Flashcards

Study the latissimus dorsi muscle, including its attachments, thoracodorsal innervation, blood supply, actions, and clinical anatomy.

Card 1 of 25Question

What type of back muscle is the latissimus dorsi?

A superficial extrinsic back muscle that acts primarily on the upper limb.

In This Section

1. What type of back muscle is the latissimus dorsi?

A superficial extrinsic back muscle that acts primarily on the upper limb.

2. What is the general shape of the latissimus dorsi?

A broad, flat, triangular muscle covering much of the lower posterior trunk.

3. From which vertebral spinous processes does the latissimus dorsi typically originate?

The lower six thoracic vertebrae, T7 to T12.

4. Which fascial structure provides an extensive origin for the latissimus dorsi?

The thoracolumbar fascia.

5. Which pelvic structure provides an attachment for the latissimus dorsi?

The posterior part of the iliac crest.

6. Which ribs commonly provide additional origins for the latissimus dorsi?

The inferior three or four ribs, commonly ribs 9 to 12.

7. Which scapular region may provide an additional attachment for the latissimus dorsi?

The inferior angle of the scapula, through a variable muscular slip.

8. Where does the latissimus dorsi insert on the humerus?

The floor of the intertubercular sulcus of the humerus.

9. What happens to the latissimus dorsi tendon as it approaches its humeral insertion?

The tendon twists so that fibers from the lower part of the muscle insert more superiorly.

10. Which muscle inserts near the latissimus dorsi on the medial lip of the intertubercular sulcus?

The teres major muscle.

11. Which nerve supplies the latissimus dorsi?

The thoracodorsal nerve.

12. What are the spinal nerve roots of the thoracodorsal nerve?

C6, C7, and C8.

13. From which part of the brachial plexus does the thoracodorsal nerve arise?

The posterior cord.

14. What is the principal arterial supply of the latissimus dorsi?

The thoracodorsal artery.

15. From which artery does the thoracodorsal artery usually arise?

The subscapular artery, a branch of the third part of the axillary artery.

16. Which additional arteries contribute to the blood supply of the latissimus dorsi?

Perforating branches of the posterior intercostal and lumbar arteries.

17. Which vein provides the principal venous drainage of the latissimus dorsi?

The thoracodorsal vein, which typically drains into the subscapular vein.

18. What are the three primary movements produced by the latissimus dorsi at the shoulder?

Extension, adduction, and medial rotation of the humerus.

19. How does the latissimus dorsi assist when pulling the body upward during climbing?

It pulls the humerus toward the trunk when the upper limb is fixed.

20. What is the role of the latissimus dorsi during forceful shoulder extension?

It draws the humerus posteriorly, particularly from a flexed position.

21. Which muscles form the posterior axillary fold?

The latissimus dorsi and teres major.

22. What is the relationship of the latissimus dorsi to the superficial triangle of auscultation?

Its superolateral border forms the inferior boundary of the triangle.

23. Which structures form the boundaries of the lumbar triangle of Petit?

Latissimus dorsi posteriorly, external oblique anteriorly, and the iliac crest inferiorly.

24. What movement may be weakened by injury to the thoracodorsal nerve?

Shoulder extension, adduction, and medial rotation, especially during resisted pulling.

25. Why is the latissimus dorsi commonly used in reconstructive surgery?

Its broad muscle mass and reliable thoracodorsal vascular pedicle make it suitable for tissue flaps.