MUSCLES OF THE BODY. 



127 



sion in which the fibres coming 

 from the fascia of origin are in- 

 serted into the lamina; 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, 1) 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 (r), partially 

 dividing it lengthwise into two 



parts. Fibres taking origin from haye been removed, the deep layer {c) 

 ,, 1 , . f r-1 • • . being cut where it passes into the longis- 



the lateral surface of this mter- sh^ul dorsi. i, crest of ihum; 4-7, Ups 

 mediate sheet curve cranioven- 

 trad, and are inserted on the 

 transverse processes of the lum- 

 bar vertebrae. Fibres taking 

 origin from the medial surface 

 of the sheet pass mediocraniad 

 and are inserted into the acces- 

 sory processes and the surfaces' 

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



hx 





Fig. 70. — Muscles on the Dorsal 

 Side of the Vertebral Column 

 IN THE Lumbar, Sacral, and Cau- 

 dal Regions. 



Both sheets of the lumbodorsal fascia 



of spinous processes of the fourth to 

 seventh lumbar vertebree. /, //, tips of 

 spinous processes of first two sacral ver- 

 tebrae, a, b, M. longissimi dorsi {a, 

 medial portion ; b, l.'\teral portion ; b' , 

 portion taking origin from the lumbo- 

 dorsal fascia); c. cut edge of deep layer 

 of lumbodorsal fascia; d, M. multifidus 

 spinae; e, M. extensor caudse medialis; 



y", M. extensor caudae lateralis, 

 abductor caudte externus. 



^. 



M, 



