THE TRANS VERSOSPINALES. 317 



and from the articular processes of the three and sometimes four succeeding cervical 

 vertebrae, together with the capsular ligaments uniting them ; it is also frequently 

 joined by one or two slender fasciculi from the lowest cervical or highest dorsal 

 spines. It is inserted into the large internal impression between the two curved 

 lines of the occipital bone. It is narrower above than below, and its inner margin 

 in the neck is in contact with the ligament um nuchas. An irregular, commonly 

 imperfect, tendinous intersection crosses the muscle about the level of the spine of 

 the axis ; and lower down, another longer one interrupts the fibres of the inner 

 portion of the muscle, which is more or less separate from the rest, and ~is hence 

 sometimes described independently under the name of bwenter cervicis. 



Relations. The complexus muscle is covered by the splenius, except at its lowest origins 

 from the dorsal vertebras and at the internal portion of its upper extremity ; the trachelo- 

 mastoid and transversalis cervicis rest upon its series of origins ; and the semispinalis colli r 

 the posterior recti, and the obliqui capitis, together with the deep cervical vessels, are con- 

 cealed by it. 



The semispinalis muscle consists of bundles of fibres extending from transverse 

 processes to spines, and crossing over from four to six vertebras. It is described in 

 two parts. 



a. The semispinalis colli is the part under cover of the complexus. It arises 

 from the upper five or six dorsal transverse processes, and is inserted into the spines 

 of the cervical vertebrae from the second to the fifth inclusive, being thickest at its 

 insertion into the second vertebra. 



#. The semispinalis dorsi consists of narrow muscular bundles interposed 

 between tendons of considerable length, and forms an elongated thin stratum, 

 especially towards its lower border. It arises from the transverse processes of the 

 dorsal vertebras from the sixth to the tenth inclusive, and is inserted into the last 

 two cervical and from four to six upper dorsal spines. 



The multifidus spinae muscle occupies the vertebral groove by the side of the 

 row of spinous processes, reaching from the sacrum to the axis, and passing up 

 under cover of the semispinalis. It is more largely developed towards the lower 

 than at the upper end of the column, and is thinnest in the dorsal region. In the 

 sacral region the fibres arise from the deep surface of the tendinous origin of the 

 erector spinas, from the groove on the back of the sacrum as low as the fourth 

 foramen, from the inner part of the posterior extremity of the ilium, and from the 

 posterior sacro-iliac ligament ; in the lumbar region they take origin from the 

 mamillary processes ; in the dorsal region from the transverse processes ; and in the 

 neck from the articular processes of the four lower cervical vertebras. From these 

 several points the muscular bundles ascend obliquely, to be inserted into the spines 

 of the vertebras, from their bases to their extremities. The fibres from each point 

 of origin are fixed to several vertebrae, some being inserted into the side of the 

 spinous process next but one above, and others ascending more and more vertically 

 as high as the fourth from the place of origin, the longer fibres from one origin 

 overlapping those from the origin next above. 



The rotatores dorsi are eleven small muscles on each side, which may be 

 regarded as the deepest fibres of the multifidus spinae in the dorsal region, and are 

 distinguished by being more nearly horizontal than the rest. Each arises from the 

 upper and back part of the transverse process of one vertebra, and is inserted into 

 the inferior margin of the lamina of the vertebra next above. 



Varieties. The highest one or two, or the lowest of the rotator muscles may be wanting. 

 Similar small slips between adjacent vertebra, but more longitudinal in direction, are occa- 

 sionally present in the cervical and lumbar regions. The rotatores longl of Henle are inconstant 

 slips passing from the transverse process of one dorsal vertebra to the root of the spine of the 

 second, or even the third vertebra above. 



