SIXTH LAYER. 205 



process of the atlas, and is inserted into the rough surface of the occi- 

 pital bone, external to the condyle. 



The OBLIQUUS INFERIOR arises from the spinous process of the 

 axis, and passes obliquely outwards to be inserted into the extremity 

 of the transverse process of the atlas. 



The OBLIQUUS SUPERIOR arises from the extremity of the trans- 

 verse process of the atlas, and passes obliquely inwards to be inserted 

 into the rough surface of the occipital bone, between the curved lines. 



Relations. By their superficial surface the recti and obliqui are in 

 relation with a strong aponeurosis Avhich separates them from the corn- 

 plexus. By their deep surface with the atlas and axis, and their arti- 

 culations. The rectus posticus major partly covers in the rectus minor. 



The rectus lateralis is in relation by its anterior surface with the 

 internal jugular vein, and by its posterior surface with the vertebral 

 artery. 



Sixth Layer. 



Dissection. The semi-spinales muscles must both be removed to 

 obtain a good view of the multifidus spina? which lies beneath them, 

 and fills up the concavity between the spinous and transverse processes, 

 the whole length of the vertebral column. 



The MULTIFIDUS SPIN.S: consists of a great number of fleshy fasci- 

 culi extending between the transverse and spinous processes of the 

 vertebrae, from the sacrum to the axis. Each fasciculus arises from a 

 transverse process, and is inserted into the spinous process of the first 

 or second vertebra above. Some deep fasciculi of the multifidus 

 spinae have recently been described by Professor Theile under the 

 name of rotatores spines. 



Relations. By its superficial surface with the longissimus dorsi, 

 semi-spinalis dorsi, and semi-spinalis colli. By its deep surface with 

 the arches and spinous processes of the vertebral column, and in the 

 cervical region with the ligamentum nuchse. 



The LEVATORES COST ARUM, twelve in number on each side, arise 

 from the transverse processes of the dorsal vertebrae, and pass ob- 

 liquely outwards and downwards to be inserted into the rough surface 

 between the tubercle and angle of the rib below them. The first of 

 these muscles arises from the transverse process of the last cervical 

 vertebra, and the last from that of the eleventh dorsal. The levatores 

 of the inferior ribs, besides the distribution here described send a 

 fasciculus downwards to the second rib below their origin, and conse- 

 quently are inserted into two ribs. 



Relations. By their superficial surface with the longissimus dorsi 

 and sacro-lumbalis. By their deep surface with the intercostal muscles 

 and ribs. 



The SUPRA-SPJNALIS is a small and irregular muscle lying upon 

 the spinous processes in the cervical region and composed of several 

 fasciculi. The fasciculi arise from the inferior cervical and superior 



