MUSCLES OF THE BODY. 



127 



C 



sion in which the fibres coming 

 from the fascia of origin are in- 

 serted into the laminae and trans- 

 verse processes of the thoracic 

 vertebrae. 



The lateral division (Fig. 

 70, b) is much larger than the 

 medial one, forming in the 

 lumbar region a nearly cylin- 

 drical mass. 



Origin from the crest of the 

 ilium (Fig. 70, i) and the medial 

 surface of the ilium as far caudad 

 as the auricular impression ; also 

 from the deep layer of the lum- 

 bodorsal fascia (c). This fascia 

 is connected with the crest of 

 the ilium and with the tips of 

 the spinous processes of the 

 vertebrae in the lumbar and 

 thoracic regions, and from it a 

 large proportion of the fibres of 

 the longissimus take origin. In 

 the lumbar region it dips into 

 the muscle as an intermediate 

 longitudinal sheet (<:), partially 

 dividing it lengthwise into two 



parts. Fibres taking origin from have been removed, the deep layer (c) 

 . , . , t r . , . . , being cut where it passes into the longis- 



the lateral surface of this inter- simu | dorsi I? cres t of ilium; 4-7, tips 

 mediate sheet curve cranioven- of spinous processes of the fourth to 



. seventh lumbar vertebrse. /. //, tips of 



trad, and are inserted on the spinoos processes of first two sacral ver- 



transverse processes of the lum- tebl ?- * ?> M - l n g'ssi dorsi (a 



medial portion ; o, lateral portion ; b , 

 bar vertebras. Fibres taking portion taking origin from the lumbo- 



origin from the medial surface ^Sl'iSifS M.13& 



of the sheet pass mediocraniad spinae; e, M. extensor caudse medialis; 

 i . . , /, M. extensor caudse lateralis. g, M. 



and are inserted into the acces- -; bductor caudK e xternus. 



sory processes and the surfaces 



of the vertebral arches. In the thoracic region (Fig. 69, f) 



FIG. 70. MUSCLES ox THE DORSAL 

 SIDE OF THE VERTEBRAL COLUMN 

 IN THE LUMBAR, SACRAL, AND CAU- 

 DAL REGIONS. 

 Both sheets of the lumbodorsal fascia 



