433 THE MUSCLES AND FASCIA 



costalis is continued upward to the upper ribs and cervical portion of the spine. 

 The accessory portions form two additional muscles, the Musculus accessorius and 

 the Cervicalis ascendens. 



The Musculus accessorius ad ilio-costalem arises, by separate flattened tendons, 

 from the angles of the six lower ribs ; these become muscular, and are finally 

 inserted, by separate tendons, into the angles of the six upper ribs. 



The Cervicalis ascendens 1 is the continuation of the Accessorius upward into 

 the neck ; it is situated on the inner side of the tendons of the Accessorius, arising 

 from the angles of the four or five upper ribs, and is inserted by a series of slender 

 tendons into the posterior tubercles of the transverse processes of the fourth, fifth, 

 and sixth cervical vertebrae. 



The Longissimus dorsi is the inner and larger portion of the Erector spinae. 

 In the lumbar region, where it is as yet blended with the Ilio-costalis, some of the 

 fibres are attached to the whole length of the posterior surface of the transverse 

 processes of the lumbar vertebrae, to the tubercles at the back of the articular 

 processes, and to the middle layer of the lumbar fascia. In the dorsal region the 

 Longissimus dorsi is inserted, by long thin tendons, into the tips of the transverse 

 processes of all the dorsal vertebrae, and into from seven to eleven of the lower 

 ribs between their tubercles and angles. This muscle is continued upward, to the 

 cranium and cervical portion of the spine by means of two additional muscles, the 

 Transversalis colli and Trachelo-mastoid. 



The Transversalis colli (or cervicis), placed on the inner side of the Longis- 

 simus dorsi, arises by long thin tendons from the summits of the 'transverse pro- 

 cesses of the six upper dorsal vertebrae, and is inserted by similar tendons into 

 the posterior tubercles of the transverse processes of the cervical vertebrae from 

 the second to the sixth. 



The Trachelo-mastoid lies on the inner side of the preceding, between it and the 

 Complexus muscle. It arises, by four tendons, from the transverse processes of 

 the third, fourth, fifth, and sixth dorsal vertebrae, and by additional separate 

 tendons from the articular processes of the three or four lower cervical. The fibres 

 form a small muscle, which ascends to be inserted into the posterior margin of 

 the mastoid process, beneath the Splenius and Sterno-mastoid muscles. This 

 small muscle is almost always crossed by a tendinous intersection near its insertion 

 into the mastoid process. 2 



Relations. The Erector spinae and its prolongations are bound down to the 

 vertebrae and ribs in the lumbar and dorsal regions by the lumbar fascia and the 

 vertebral aponeurosis. The inner part of these muscles covers the muscles of the 

 fifth layer. In the neck they are in relation, by their superficial surface, with the 

 Trapezius and Splenius ; by their deep surface, with the Semispinalis dorsi et colli 

 and the Recti and Obliqui. 



The Spinalis dorsi connects the spinous processes of the upper lumbar and the 

 dorsal vertebrae together by a series of muscular and tendinous slips which are 

 intimately blended with the Longissimus dorsi. It is situated at the inner side of 

 the Longissimus dorsi, arising, by three or four tendons, from the spinous pro- 

 cesses of the first two lumbar and the last two dorsal vertebrae : these, uniting, 

 form a small muscle, which is inserted, by separate tendons, into the spinous pro- 

 cesses of the dorsal vertebrae, the number varying from four to eight. It is ' 

 intimately united with the Semispinalis dorsi, which lies beneath it. 



The Spinalis colli is a small muscle, connecting together the spinous processes 

 of the cervical vertebrae, and analogous to the Spinalis dorsi in the dorsal region. 

 It varies considerably in its size and in its extent of attachment to the vertebrae, 

 not only in different bodies, but on the two sides of the same body. It usually 

 arises by fleshy or tendinous slips, varying from two to four in number, from the 



1 This muscle is sometimes called " Cervicaiis uescendens." The student should remember 

 that these long muscles take their fixed point from above or from below according to circumstances. 



2 These two muscles are sometimes described as one, having a common origin, but dividing above 

 at their insertion. The Trachelo-mastoid is then termed the Transversalis capitis. 



