THE SUPERIOR EXTREMITY 



M. Latissimus Dorsi. The latissimus dorsi is a wide, flat 

 muscle, which covers the back from the level of the sixth 

 thoracic vertebra down to the crest of the ilium (Fig. 26, p. 52). 

 It arises (i) from the tips of the spinous processes of the 

 lower six thoracic vertebrae and the supraspinous ligaments in 

 connection with them; (2) from the superficial lamella of 

 the lumbo-dorsal fascia (Fig. 26) ; (3) by a thin tendinous origin 

 from a small extent of the outer lip of the crest of the ilium, in 



FIG. 29. Diagram of the Lumbo-dorsal Fascia. 



6. Fascia transversalis. 



7. Sacrospinalis. 



8. Quadratus lumborum 



9. Psoas major. 



1. Serratus posterior inferior. 



2. Latissimus dorsi. 



3. Transversus abdominis. 



4. Obliquus internus. 



5. Obliquus externus. 



front of the lumbo-dorsal fascia (Fig. 26, p. 52); (4) by three 

 or four digitations from the lower three or four ribs; and (5) 

 by a fleshy slip from the dorsal aspect of the inferior angle 

 of the scapula (Fig. 38, p. 83). By means of its origin from 

 the posterior lamella of lumbo-dorsal fascia, it attains an in- 

 direct attachment to the spines of the lumbar and upper sacral 

 vertebrae, and also to the posterior part of the crest of the 

 ilium. The costal slips of origin interdigitate with the lower 

 digitations of the external oblique muscle of the abdominal 

 wall. 



The fibres of the latissimus dorsi converge rapidly as 



