im 



PHYSIOLOGY. 



with the posterior columns, then there would be ground for the behef 

 that the functions of the columns corresponded with those of the roots; 

 but nothing is more certain than that both roots are connected with 

 the antero-lateral columns ; and there is a doubt as to whether the 

 posterior roots have any connexion at all with the posterior column. 

 Hence they are disposed to believe that the antero-lateral columns 

 are both inoior and sensitive. They aro also disposed to believe 

 that the posterior columns have a function different from that usually 

 assigned to them. They may be in part commissural between the 

 various segments of the cord, and in part subservient to the function 

 of the cerebellum in co-ordinating and regulating the movement ne- 

 cessary for perfect locomotion. 



FUNCTIONS OF THE MEDULLA OBLONGATA. 



The brain and spinal cord act on each other through the medium 

 of the medulla oblongata ; hence the importance of a knowledge of 

 the course of the different columns or bundles of fibres of these parts. 

 It consists o^four principal parts. 1st. The Anterior Pyramids^ or 



Fig. 27.* Fig. 28.t 



s 



Corpora Pyraniidalia ; 2d. The Olivary Bodies, or Corpora OH- 

 varia ; 3d. Restiform Bodies, or Corpora Restiformio. ; sometimes 

 called Processus a Cerebello ad Medullarn Oblongatam ; 4th. The 



* Front view of medulla oblongata, pp. Pyramidal bodies, decussating at d. oo. Olivary 

 bodies, rr. Restiform bodies, aa. Arciform fibres. 



t Posterior view of medulla oblongata, pp. Posterior pyramids, rr. Restiform bodies, 

 composed of cc. posterior columns, and dd. lateral part of antero-lateral columns, aa. Oli- 

 vary columns, as seen on the floor of the fourth ventricle, nn. Fibres of seventh pair of 

 nerves. 



