168 HEAD AND NECK 



lower border blends with the ilio-lumbar ligament. The 

 dissector should verify these various attachments by passing 

 his fingers over the posterior surface of the lamella from its 

 lateral to its medial border, and from its upper to its lower end. 



Dissection. After satisfying himself regarding the lamellae of the lumbar 

 part of the lumbo-dorsal fascia and their relations to the posterior spinal 

 muscles, to the quadratus lumborum, and to the internal oblique and the 

 transversus abdominis muscles, the dissector should make a longitudinal 

 incision through the anterior lamella, and the peri-renal fascia anterior to it ; 

 and, introducing his finger through the opening into the extra- peritoneal 

 fatty tissue, he should scrape away the latter until he exposes the kidney, 

 below the level of the last rib, and the adjacent part of the colon, which 

 lies along the lower and lateral part of the kidney. After this has been 

 done he should reflect the serratus posterior superior and secure its nerves 

 of supply which spring from the upper intercostal nerves and enter its deep 

 surface ; then he should remove the thoracic part of the lumbo-dorsal fascia 

 and commence the study of the posterior spinal muscles, beginning with 

 the splenius. 



Musculus Splenius. The splenius has a continuous origin 

 from the lower half of the ligamentum nuchae, and from the 

 spines of the seventh cervical and upper six thoracic vertebrae. 

 Its fibres pass obliquely upwards and laterally, forming a thick 

 flat muscle, which soon divides into a cervical and a cranial 

 portion, termed respectively the splenius cervicis and the 

 splenius capitis. 



The splenius cervicis turns anteriorly and is inserted by 

 tendinous slips into the tubercles of the transverse processes 

 of the upper two or three cervical vertebrae, medial to the 

 levator scapulae. 



The splenius capitis passes under cover of the upper part 

 of the sterno-mastoid muscle, and gains insertion into the 

 lower part of the mastoid portion of the temporal bone and 

 into the lateral portion of the superior nuchal line of the 

 occipital bone. To see this insertion, the sterno-mastoid 

 muscle may be divided along the superior nuchal line, but 

 it must not be detached from the temporal bone. 



Dissection. The deeper spinal muscles must now be dissected. Begin 

 by reflecting the splenius muscle. Detach it from its origin and throw 

 it laterally and upwards towards its insertion. Whilst doing this, preserve 

 the cutaneous branches of the cervical nerves which pierce it. 



When the splenius capitis is fully reflected, a small triangular space 

 will be noticed close to the superior nuchal line of the occipital bone. 

 Anteriorly, it is bounded by the longissimus capitis (O.T. trachelo-mastoid) ; 

 posteriorly, by the lateral border of the semispinalis capitis (O.T. corn- 

 plexus) ; and above, by the superior nuchal line of the occipital bone. 

 The floor of this little space is formed by the superior oblique muscle of 



