j THE MUSCLES OF THE BACK. 367 
of the vertebral aponeurosis from the last two thoracic and first two lumbar spinous 
processes. It forms four muscular bands which pass almost horizontally outwards 
to an insertion into the last four ribs. The muscular slips overlap one another 
from below upwards. The muscle is on the same plane as the vertebral aponeu- 
rosis, and is concealed by the latissimus 
dorsi. 
The splenius muscle occupies the 
back of the neck and upper part of the 
thoracic region. It arises as a flattened 
band from the ligamentum nuchee (from 
the level of the fourth cervical vertebra 
downwards) and from the spinous pro- 
cesses of the last cervical and higher 
our, to six), thoracic, vertebrae, . [tig 124cu=oatsto 
fibres extend upwards and outwards 
COMPLEXUS 
into the neck, separating in their course —Traysversauis___ \ 
into an upper and a lower part. The cn es Va 
upper part forms the splenius capitis, Y } 
a! 
which is inserted into the mastoid pro- CERVICALIS— 
cess and the outer part of the superior oa aa 
curved line of the occipital bone. The 
lower part forms the splenius colli or 
cervicis, which is inserted into the 
posterior tubercles of the transverse pro- 
cesses of the upper three or four cervical 
vertebree behind the origin of the 
levator anguli scapule. The muscle is 
partially concealed by the trapezius and 
sternomastoid, and appears between 
them in the floor of the posterior tri- 
angle of the neck. It is covered by 
— 
—— 
SSS 
aS ses shay 
pprmanace 
y} 
Yf 
1) 
a 
\/ 
ACCESSORIUS F 
>) 
LONGISSIMUS 
DORSI 
ry \ 
are 
TI 7/1 pS ps 
ary 
as 
iA 
the rhomboid muscles, levator anguli Sey 
scapulz and serratus posticus superior. 5.15 cconri 
. sibs “COSTA SS) 
It conceals the transversalis cervicis, 
trachelo-mastoid,andcomplexus muscles. 
a < ERECTOR 
SECOND GROUP. SPINE 
The erector sping (m.sacro-spinalis) 
possesses vertebral, vertebro-cranial, and ) 
vertebro-costal attachments. It con- ee 
sists of an elongated mass composed 
of separated shps extending from the 
sacrum to the skull. Simple at its 
origin, it becomes more and more com- 
plex as it is traced upwards towards the 
head. It arises (1) by fleshy fibres from 
the iliac crest; (2) from the posterior 
sacro-iliac ligament; and (3) by ten- 
dinous fibres continuous with the former i 
Me tis rest che back of. the FIG. Es nny EE SEN UA EICN OF THE PaRtTs 
> OF THE ERECTOR SPINH% MUSCLE. 
sacrum, and the spines of the upper 
sacral and all the lumbar vertebrae. Its fibres extend upwards through the loin, 
enclosed between the posterior and middle layers of the lumbar fascia, and separate 
into two columns, an outer portion derived from the external fleshy origin, the 
ilio-costalis, and an inner portion comprising the remaining larger part of the 
muscle, the longissimus dorsi. 
| The ilio-costalis (m. ilio-costalis lumborum) is inserted by six slender slips into 
the lower six ribs. 
