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 splenitis on the mastoid 

 portion of the skull, 

 (b) 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. 



