438 THE MUSCLES AND FASCIA 



fifth cervical. The fasciculus connected with the axis is the largest, and chiefly 

 muscular in structure. 



Relations. By their superficial surface, from below upward, with the Spinalis 

 dorsi, Longissimus dorsi, Splenius, Complexus, the profunda cervicis artery, the 

 princeps cervicis artery, and the internal branches of the posterior divisions of 

 the first, second, and third cervical nerves ; by their deep surface, with the Mul- 

 tifidus spinae. 



The Multifidus spinse consists of a number of fleshy and tendinous fasciculi 

 which fill up the groove on either side of the spinous processes of the vertebrae, 

 from the sacrum to the axis. In the sacral region these fasciculi arise from the 

 back of the sacrum, as low as the fourth sacral foramen, and from the aponeurosis 

 of origin of the Erector spinae ; in the iliac region, from the inner surface of the 

 posterior superior spine of the ilium and posterior sacro-iliac ligaments ; in the lum- 

 bar regions, from the articular processes ; in the dorsal region, from the trans- 

 verse processes ; and in the cervical region, from the articular processes. Each 

 fasciculus, passing obliquely upward and inward, is inserted into the lamina and 

 whole length of the spinous process of one of the vertebrae above. These fasciculi 

 vary in length : the most superficial, the longest, pass from one vertebra to the 

 third or fourth above ; those next in order pass from one vertebra to the second or 

 third above ; whilst the deepest connect two contiguous vertebras. 



Relations. By its superficial surface, with the Longissimus dorsi, Spinalis 

 dorsi, Semispinalis dorsi, and Semispinalis colli ; by its deep surface, with the 

 laminae and spinous processes of the vertebrae, and with the Rotatores spinae in 

 the dorsal region. 



The Rotatores spinse are found only in the dorsal region of the spine, beneath 

 the Multifidus spinae ; they are eleven in number on each side. Each muscle 

 is small and somewhat quadrilateral in form ; it arises from the upper and back 

 part of the transverse process, and is inserted into the lower border and outer 

 surface of the lamina of the vertebra above, the fibres extending as far inward as 

 the root of the spinous process. The first is found between the first and second 

 dorsal ; the last, between the eleventh and twelfth. Sometimes the number of 

 these muscles is diminished by the absence of one or more from the upper or lower 

 end. 



The Supraspinales consist of a series of fleshy bands which lie on the spinous 

 processes in the cervical region of the spine. 



The Interspinales are short muscular fasciculi, placed in pairs between the 

 spinous processes of the contiguous vertebrae, one on each side of the interspinous 

 ligament. In the cervical region they are most distinct, and consist of six pairs, 

 the first being situated between the axis and third vertebra, and the last between 

 the last cervical and the first dorsal. They are small narrow bundles, attached, 

 above and 'below, to the apices of the spinous processes. In the dorsal region 

 they are found between the first and second vertebrae, and occasionally between 

 the second and third ; and below, between the eleventh and twelfth. In the 

 lumbar region there are four pairs of these muscles in the intervals between the 

 five lumbar vertebrae. There is also occasionally one in the interspinous space, 

 between the last dorsal and first lumbar, and between the fifth lumbar and the 

 sacrum. 



The Extensor coccygis is a slender muscular fasciculus, occasionally present, 

 which extends over the lower part of the posterior surface of the sacrum and 

 coccyx. It arises by tendinous fibres from "the last bone of the sacrum or first 

 piece of the coccyx, and passes downward to be inserted into the lower part of 

 the coccyx. It is a rudiment of the Extensor muscle of the caudal vertebrae 

 which exists in some animals. 



The Intertransversales are small muscles placed between the transverse pro- 

 cesses of the vertebrae. In the cervical region they are most developed, consisting 

 of rounded muscular and tendinous fasciculi, which are placed in pairs, passing 

 between the two anterior and the two posterior tubercles of the transverse processes 



