212 MUSCLES OF THE TRUNK AND CHEST. 



much the smallest. Of the two remaming pleurae, the left 

 is the smaller ; because there is an extra lobe to the right 

 lung, and the right pleura having consequently to make room 

 for the largest contents. 



MUSCLES OF THE TRUNK AND CHEST. 



Lateralis sterni. Origin. From the body of the ster- 

 num, and the cartilages of the fourth and fifth ribs. In- 

 sertion. Into the first rib. 



Superficialis costarum {Plate III. b), by fine aponeu- 

 rosis from the ligamentum supra spinalis of the back and 

 loins. Insertion. Into the anterior margin of the fifth to 

 the twelfth ribs ; and into the posterior borders of from the 

 twelfth to the eighteenth ribs. 



Transversalis costarum. Origin of the superficial ten- 

 dons. From the first lumbar vertebrae. Origin of the deep- 

 seated tendons. From the transverse process of the seventh 

 cervical vertebrae. Insertion of the superficial tendons. 

 Passing over the last three ribs into the posterior borders 

 of the fifteenth and all anterior ribs, reaching to the trans- 

 verse process of the seventh cervical. Insertion of the deep- 

 seated tendons. Passing over the first two ribs into the 

 inferior margin of the third and all posterior fibs, reaching 

 to the transverse process of the first lumbar vertebrae. 



LoNGissiMus DORSi {Plate III. F). Bifid posteriorly. 

 Origin. From the transverse processes and ligamentum 

 supra spinalis of the sacral and lumbar regions, and as far 

 forward in the dorsal as the eleventh vertebrae. From the 

 transverse processes of all the remaining vertebrae ; and to 

 the tendon of the complexus major. Inserted. Into the 

 bottom and margin of both spines of the ilium ; into the 

 transverse processes of the lumbar vertebrae ; and into the 

 ribs, as well as into the last four, but sometimes five cer- 

 vical vertebrae. 



Spinalis DORSi {Plate 111. G). Origin. From the tendon 

 covering the longissimus dorsi ; and from the anterior twelve 

 dorsal spines. Inserted. Into the last four cervical vertebral 

 spines. 



Intercostals (PZa^e III. «). Internal and external. Ori- 

 gin. External, from the posterior border of each rib. In- 

 ternal, from the anterior border of each rib. Insertion. 



