238 DORSAL MUSCLES OF THE TRUNK. 



b. The semispinalis dorsi, not covered by the complexus, consists of small 

 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 vertebrae from the tenth to 

 the fifth inclusive, and is inserted into the spines of the last two cervical 

 and first four dorsal vertebrae. 



The multifidus spince reaches from the sacrum to the axis vertebra, passing 

 up under cover of the semispinalis, and is much more largely developed 

 towards the lower than the -upper end of the column. In the sacral region 

 the fibres arise from the deep surface of the tendinous origin of the erector 

 spinae, from the groove on the back of the sacrum as low as the fourth fora- 

 men, from the inner part of the posterior extremity of the iliac crest, and 

 from the ligaments between that bone and the sacrum ; in the lumbar 

 region they take origin from the mammillary processes ; in the dorsal 

 region from the transverse processes ; and in the neck from the articular 

 processes of the four lower cervical veitebrse. From these several points 

 the muscular bundles ascend obliquely, to be inserted into the laminae of the 

 vertebrae, and into the spines from their bases nearly 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 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 spince are eleven pairs of small muscles, which may be 

 regarded as the deepest fibres of the multifidus spinse 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, and is inserted 

 into the vertebra next above, at the inferior margin and on part of the 

 surface of the lamina, as far as the root of the spinous process. 



INTERTRANSVERSALES. The intertransversales are short muscles passing 

 nearly vertically from vertebra to vertebra between the transverse processes. 

 They are most developed in the cervical, and least in the dorsal region. 

 Beneath each cervical transverse process there are two such muscles, one 

 descending from the anterior, and another from the posterior part of the 

 process. In the lumbar region there are likewise two sets : one set, the 

 intertransversales laterales, lie between the transverse processes, and are in 

 series with the levatores costarum ; the other set, intertransversales mediates 

 or interaccessorii, pass from the accessory process of one vertebra to the 

 mammillary process of the next, and are in series with the intertransversales 

 of the dorsal region. 



INTERSPINALES. The interspinales are short vertical fasciculi of fleshy 

 fibres, placed in pairs between the spinous processes of the contiguous verte- 

 brae. They are best marked in the neck, where they are connected one to 

 each of the two parts into which the spinous process is divided. In the dorsal 

 part of the column only a few are met with, and these are not constant. 



The spinalis cervicis consists of a few irregular bundles of fibres, of greater length 

 than the preceding muscles, placed close to the ligamentum nuchee : they arise by 

 two or more heads from the spines of the fifth and sixth cervical and sometimes other 

 neighbouring vertebrae, and are inserted into the spine of the axis, and occasionally 

 into the two vertebrae next below it. This muscle is sometimes wanting. (See 

 Henle and Heilenbeck, in " MUller's Archiv," 1837.) 



The name sacro-coccygcus posticus, or extensor coccygis, has been given to slender 

 fibres occasionally found extending from the lower end of the sacrum to the coccyx, 



