Chap. 12.] Neck and Back, &V. 153 



of the fcapula, which it draws obliquely upwards, and 

 directly inwards towards the fpine. 



On the neck is fituated. 



The fplenius, which arifes from the fpinous pro-? 

 ceffes of the four upper vertebrae of the back and five 

 lower of the neck ; it is inferted into the tranfverfe 

 proceffes of the five fuperior vertebra? of the neck, 

 the poflerior part of the maftoid procefs, and the os 

 occipitis, -where it joins the root "of that procefs* 

 When one of thefe mufcles acts, it brings the head 

 and neckly obliquely backwards, or, when they both 

 act, they draw the head diredtly backwards. 



The fingle- pair, which was mentioned* is the 



Serratus pofticus fuperior. This originates from 

 the fpinous procefTes of the three lowed vertebras of 

 the neck, and two uppermoft of the back, and is in- 

 ferted into the fecond, third, fourth, and fifth ribs. 

 Its effect is to elevate the ribs, dilate the thorax, and 

 confequently it is fubfervient to infpiration. 



Having removed thefe mufcles, we come to the 

 third layer, which confifts of three on the back, and 

 three on the neck. 



On the back are, 



The fpinalis dorfi, which arifes from the fpinous 

 precedes of the two uppermoft vertebrae of the loins 

 and three inferior of the back, and paries to the nine 

 uppermoft fpinous proceffes of the vertebras of the 

 back. The evident effect of this mufcle is to ftraiten 

 the fpine, and prevent it from bending forwards. 



The longiflimus dorfi originates from the fide of 

 the os facrum, and its fpinous proceffes j from the 

 pofterior fpine of the ileum ; from all the fpinous 

 procefles, and from the roots of the tranfverfe proceflcs 

 of the vertebras of the loins. It is inferted into all 

 the tranfverfe procefies of the vertebras of the back, 



and 



