112 THE SPINAL CORD AND CEREBELLUM 



slight extent only in the thoracic region. Evidently, 

 if this be so, the lateral group must differ in function 

 from the others, and if the median group be as 

 suggested, commissure cells, it seems natural to 

 connect the group of smaller cells at the base of the 

 anterior horn with vaso-motor or secreto-motor 

 functions. 

 In the A group of cells has been defined in the lateral 



lateral ^ ^ 



horn. horn which is well marked in the thoracic region, and 

 is discernible in the lumbar region, but becomes 

 confused with the lateral group of the anterior horn 

 in the cervical portion of the cord. This group is 

 thought to be motor to the intestines.* 



In the Two groups, known as the posterior lateral reticular 



posterior 



horn. formation and the lateral reticular formation, occupy 

 a position about the centre of the posterior horn, 

 which, roughly speaking, they bisect. They are 

 found throughout the cord, being most conspicuous in 

 the cervical region. Near the base of the posterior 

 horn, on the inner side, is a very important group of 

 cells already mentioned, viz., the vesicular cylinder 

 or Clarke's column. The cells of this group are large 

 and fusiform. They lie with their long axis length- 

 ways along the cord, surrounded by, or, as it were, 

 embedded in, a mass of fibres. This group is very 

 prominent in the central portion of the cord, extending 

 from about the eighth cervical nerve to the third 

 lumbar nerve. It has been recognised again opposite 

 to the second and third cervical nerves, and is 

 * Bechterew, loc. cit., p. 26. 



