MUSCLES OF 
sion in which the fibres coming 
from the fascia of origin are in- 
serted into the lamine and trans- 
verse processes of the thoracic 
vertebre. 
The lateral division (Fig. 
70, 6) is much larger than the 
medial one, forming in the 
lumbar region a nearly cylin- 
drical mass. 7] 
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 (¢). This fascia 
is connected with the crest of 
the ilium and with the tips of 
the spinous processes of the 
vertebra 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 (c), partially 
dividing it lengthwise into two 
parts. Fibres taking origin from 
the lateral surface of this inter-° 
mediate sheet curve cranioven- 
trad, and are inserted on the 
transverse processes of the lum- 
bar vertebrze. Fibres taking 
origin from the medial surface 
of the sheet pass mediocraniad 
and are inserted into the acces- 
sory processes and the surfaces 
THE BODY. 127 
63 
LE 
fi 
SSSssSSS= ZS Z BY 
fe 
Fic. 70.—MUuSCLE3 ON THE DorRSAL 
SIDE OF THE VERTEBRAL COLUMN 
IN THE LUMBAR, SACRAL, AND CAU- 
DAL REGIONS. 
Both sheets of the lumbodorsal fascia 
have been removed, the deep layer (c) 
being cut where it passes into the longis- 
simus dorsi. 1, crest of ilium; 4-7, tips 
of spinous processes of the fourth to 
seventh lumbar vertebre,  //, tips of 
spinous processes of first two sacral ver- 
tebree. a, 4, M. longissimi dorsi (a, 
medial portion; 4, lateral portion; 6’, 
portion taking origin from the lumbo- 
dorsal fascia); ¢, cut edge of deep layer 
of lumbodorsal fascia; @, M. multifidus 
spine; ¢, M. extensor caudz medialis; 
J, M. extensor caude lateralis, g, M. 
abductor caudz externus, 
of the vertebral arches. In the thoracic region (Fig. 69, 7’) 
