178 



FOUKTII LAYER. 



Fig. 77 * 



Relations. The erector spinee muscle is in relation by its super- 

 ficial surface (in the lumbar region) with the conjoined aponeurosis 



of the transversalis and internal oblique 

 muscle, which separates it from the apo- 

 neurosis of the serratus posticus inferior, 

 and longissimus dorsi; (in the dorsal 

 region) with the vertebral aponeurosis, 

 which separates it from the latissimus 

 dorsi, trapezius, and serratus posticus 

 superior, and with the splenius. By its 

 deep surface (in the lumbar region) with 

 the multifidus spinoe, transverse processes 

 of the lumbar vertebrae, and with the 

 middle layer of the aponeurosis of the 

 transversalis abdominis, which separates 

 it from the quadratus lumborum ; (in the 

 dorsal region) with the multifidus spinae, 

 semi-spinalis dorsi, levatores costarum, 

 intercostal muscles, and ribs as far as 

 their angles. Internally or mesially with 

 the multifidus spinae, and semi-spinalis 

 dorsi, which separate it from the spinous 

 processes and arches of the vertebrae. 



The two layers of aponeurosis of the 

 transversalis abdominis, together with the 

 spinal column in the lumbar region, and 

 the vertebral aponeurosis with the ribs 

 and spinal column in the dorsal region, 

 form a complete osseo-aponeurotic sheath 

 for the erector spinae. 

 <- CERVICAL GROUP. The cervicalis as- 

 cendens^ is the continuation of the sacro- 

 lumbalis upwards into the neck. It arises from the angles of the 

 four upper ribs, and is inserted by slender tendons into the posterior 

 tubercles of the transverse processes of the four lower cervical 

 vertebrae. 



Relations. By its superficial surface with the levator anguli sca- 

 pulae ; by its deep surface with the upper intercostal muscles and 

 ribs, and with the intertransverse muscles; externally with the 



* The fourth and fifth, and part of the sixth layer of the muscles of the back. 1. The 

 common origin of the erector spinse muscle. 2. The sacro-lumbalis. 3. The longissi- 

 mus dorsi. 4. The spinalis dorsi. 5. The cervicalis ascendens. 6. The transversalis 

 colli. 7. The trachelo-mastoideus. 8. The complexus. 9. The transversalis colli, 

 showing its origin. 10. The semispinalis dorsi. 11. The semispinalis colli. 12. The 

 rectus posticus minor. 13. The rectus posticus major. 14. The bbliquus superior. 

 15. The obliquus inferior. 16. The multifidus spinae. 17. The levatores costarum. 

 18. Intertransversales. 19. The quadratus lumborum. 



t Called commonly the cervicalis desccndens. G. 





