(b) 
THE VERTEBRAL MUSCULATURE. 267 
serratus anterior, but a number of accessory slips carry the 
insertion forward to the transverse process of the atlas. 
This portion is the longissimus cervicis. A separate 
band of fibres arising chiefly from the transverse processes of 
the second to fourth thoracic vertebrae joins the lateral, 
ventral portion of the splenius, and forms the longissimus 
capitis. It is inserted with the splenius on the mastoid 
portion of the skull. 
The semispinalis and multifidus. The band of muscle 
lying between the longissimus and the middle line, is com- 
posed of partly fused slips, arising for the most part by very 
long tendons from the mamillary and transverse processes, 
and inserted forwards on the spinous processes. It is 
divisible into two portions, which are superficially separated 
by a constricted area lying at the level of the last thoracic 
vertebra, this being also the point where the muscle is fused 
with the longissimus. The anterior portion, the semispin- 
alis dorsi, is inserted by a series of fleshy slips on the spinous 
processes of more anterior thoracic vertebrae, but extends to 
the spinous process of the third or fourth cervical vertebra. 
The posterior portion, the multifidus, increases in size 
backward to the sacrum, where it is continuous with the 
abductor caudae posterior. 
An almost separate muscle, covering the neck as a broad 
sheet immediately beneath the splenius and longissimus 
capitis, is the semispinalis capitis. It arises from the 
transverse processes of the five posterior cervical and the 
transverse processes of the first four thoracic vertebrae. It 
is lightly attached on a line from the transverse process 
of the atlas to the external occipital protuberance, but is 
inserted on the lateral surface of the latter. The more 
posterior and medial portion of the muscle is composed of 
separate slips arising in common with the longissimus 
capitis, two closely applied slips, however, at the free margin 
of the muscle, arising from the semispinalis dorsi and the 
longissimus. The principal, lateral portion is crossed by a 
tendinous inscription. 
