THE ERECTOR SPIN^E. 



315 



Fig. 285. DEEP MUSCLES OP THE BACK. 

 (Allen Thomson.) | 



On the left side the several parts of 

 the erector spin* are nearly in their 

 natural position, with the exception of 

 the spinalis dorsi, which is drawn out 

 from the spines of the vertebras ; on the 

 right side the spinalis dorsi has been 

 entirely removed, the ilio-costalis drawn 

 to the outer side so as to expose its acces- 

 sory muscle, and the longissimus removed, 

 excepting small portions at its insertions. 

 Superiorly on the left side, the trachelo- 

 mastoid and complexus are left nearly in 

 their natural positions ; while on the right 

 side, the trachelo-mastoid has been en- 

 tirely removed, and the complexus, sepa- 

 rated from its occipital attachment, has 

 been spread out so as to stretch its ver- 

 tebral attachments, a, external occipital 

 protuberance ; b, mastoid process ; c, 

 spine of axis ; I, I, spine of first dorsal 

 vertebra and first rib ; VI, VI, VI, sixth 

 dorsal spine and transverse process and 

 sixth ribs ; XII, XII, twelfth dorsal spine 

 and twelfth ribs. On the left side, 1, 

 complexus ; 2, trachelo-mastoid ; 3, ser- 

 ratus posticus superior, detached from 

 the spine and drawn upwards from the 

 ribs ; 4, 4, slips of attachment of serratus 

 posticus inferior to lowest four ribs ; 

 5, 5, 5, costal, and 5', iliac origins of the 

 latissimus dorsi ; 6 + , tendon of origin 

 of erector spinse ; 6, upper part of longis- 

 simus dorsi ; 6', transversalis cervicis 

 continued up from longissimus ; 7, ilio- 

 costalis drawn slightly inwards to show 

 the slips of insertion into the ribs ; inside 

 the costal insertions are seen the origins 

 of the accessorius ; 7', cervicalis ascendens 

 continued upwards from accessorius ; 8, 

 spinalis dorsi. On the right side, 6, 

 marks, in the lumbar region, the inser- 

 tions of the longissimus dorsi into the 

 upper four transverse processes (the in- 

 sertion into the accessory processes not 

 being shown) ; in the dorsal region the 

 narrower tendons of insertion into the 

 lower part of the dorsal transverse pro- 

 cesses (the six lower only are repre- 

 sented) ; 6', 6', the costal insertions ; 7, 

 ilio-costalis, drawn outwards ; 7', placed 

 between lowest insertion of ilio-costalis 

 and lowest origin of accessorius ; 1", 

 cervicalis ascendens ; 9, 9, semispinalis 

 colli ; 10, 10, semispinalis dorsi; 11, 11, 

 lower dorsal and lumbar parts of the 

 multifidus spinse, which appears again 

 above the semispinalis colli, above the 

 upper 9 ; 12, levatores costarum, long 

 and short ; 13, in the upper part of the 

 figure, points by four lines to the rectus 

 capitis posticus minor and major, and the 

 obliquus inferior and superior muscles. 



original fibres passing as high as 

 the first dorsal vertebra. Inter- 

 nally it is closely connected on 

 the surface with the spinalis dorsi, the tendinous slips springing from the upper 



