Latissimus Dorsi

Variations in the extent of this muscle and its attachments are considerable. The muscle may arise only from the ribs rather from the vertebral column, ribs, scapula, and the crest of the ilium as is most common. The costal origin may be reduced to rib 12.

Mori has reported the vertebral, costal, and scapular origins for latissimus dorsi from 50 Japanese cadavers, 100 halves, as follows:

Vertebral Origin

Coastal Origin

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Scapular Origin

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The muscle may be divided into separate fascicles, frequently with one arising from the scapula. The muscle may be continuous with teres major.

Macalister described this muscle as "very liable to vary."

  1. It may have an origin from the ninth rib (Cloquet, Paxton);
  2. Or from the eight lower thoracic spines;
  3. Or from the ninth intercostal fascia (Wood);
  4. The iliac origin may be suppressed;
  5. Or reduced to a rudiment;
  6. Macalister found it extending so far forward as to overlap the external oblique;
  7. It frequently has a slip from the inferior margin of the scapula, as described by the majority of anatomists.;
  8. Macalister has seen it rising no higher, in point of origin, than the first lumbar spine;
  9. He has also seen the twelfth rib slip deficient, the muscle having but two costal orgins. Also seen by Sömmerring;
  10. A slip extending from latissimus dorsi may cross the axillary space to the tendon of pectoralis major and has been named axillary arch, achselbogen, or pectorodorsalis muscle. The axillary arch may be fused with teres major. It may extend to the brachial fascia of coracobrachialis, to the tendon of the long head of the biceps, to the first rib, to the axillary fascia, to pectoralis minor, to pectoralis quartus, or to the coracoid process. Axillary arch muscles were discovered by Ramsay in 1795 and have a dissecting room frequency of 7%. Langer (1846) is also credited with a very early description of the axillary arch. See heading Axillary Arch.
    Its frequency is given as one in thirty by Meckel, eight in one hundred and five by Struthers, six in one hundred and six by Wood. All sources totaled it occurs once in sixteen subjects (6.25%). Struthers reported it was more common in females than males, but others do not find a sex link;
  11. The achselbogen from latissimus dorsi may be attached to the lower border of pectoralis major;
  12. Or to the fascia over biceps;
  13. Or to the fascia over coracobrachialis;
  14. In one singular case it coexisted with a second slip to the fascia over the fifth digitation of serratus magnus (anterior), in the interval between the great pectoral and latissimus dorsi, which was inserted along with it; and a third, arising with the first from latissimus dorsi, passed horizontally forward to the axillary fascia over the pectoralis major;
  15. A prolongation from the costal origin of latissimus dorsi to the coracoid process may occur (Wood found it three times in one hundred and two cases. This may occur perfectly separate from the rest of latissmus (Sömmerring), in which form it is known as the chondrocoracoid of Wood and Rosenmüller, and may be inserted
    1. into the tip of the coracoid process with the pectoralis minor; or,
    2. into the lower surface of the process; or,
    3. partly into the lower border of the process, and partly into the capsule of the shoulder with the tendon of the supraspinatus. In this case Wood found it to separate the posterior from the lateral cords of the brachial plexus. Theile described a muscle of a type of chondrocoracoid, which passed from the fifth, sixth, and seventh ribs to the muscles connected with the coracoid process; another similar variety is the levator tendinis latissimus dorsi of Gruber, which may, along with variety
    4. above, be displaced varieties of coracocapsularis;
  16. A slip, tendinous (most commonly) or muscular (rarely), passes from the latissimus dorsi into the long head of triceps (Halbertsma) with a frequency of once in eighteen or once in ten. The long head of triceps derives many fibers from this tendon, or from teres major; these are believed to be rudimentary forms of dorsiepitrochlearis;
  17. The upper margin of latissimus dorsi may be united with teres major but the actual insertions are separated by a bursa;
  18. The slip from the inferior angle of the scapula has sometimes provided fasciculi that are directly continuous with the fibers of rhomboideus major, or doubled (Gruber, 1857);
  19. Langer found the costal fibers with a separate insertion into the axillary fascia;
  20. The achselbogen has been found inserted into the sheath of the long head of biceps in the bicipital groove;
  21. Meckel found latissimus arising from the eight, ninth, tenth, and eleventh ribs;
  22. Meckel saw the achselbogen coexisting with a slip of the pectoralis major going to pectoralis minor, and one to latissimus dorsi. Rüdinger (1870) illustrated a case of pectoralis major sending a slip to latissimus and a slip from latissimus going with this fascicle of tendon to the pectoral muscle.

An accessory subscapular-teres- latissimus muscle has been described. Latissimocondyloideus or dorsoepitrochlearis, a muscle found in 5% of bodies, may pass from the tendon of latissimus dorsi to the brachial and forearm fascia, to the humerus, to the lateral epicondyle and olecranon, or to the long head of triceps. Latissimus dorsi may be absent unilaterally or bilaterally.

Syn.: m. anitersor s. aniscapular, Breiter Rückenmuskel, Grand dorsal.

Axillary Arch.

From Huntington, 1905.

Axillary Arch, Pectoralis Quartus, Chondroepitrochlearis and the absence the twist of the tendon of Pectoralis Major.

From Bergman.

Chondroepitrochlearis (above) and Dorsoepitrochlearis (below)

From Perrin.

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