530 



THE NEEVOUS SYSTEM. 



Posterior columi 

 of gray matter 



segments of the spinal medulla. Now, we have noted that there is only one cell-column, 



the ventro-median column, which pursues an almost uninterrupted course throughout the 



entire length of the medulla. 



Posterior lateral furrow It may be assumed,' therefore, 

 that the nerve-fibres which go 

 to these long trunk -muscles 

 take origin in these medial 

 cells. 



Edinger states that in the 

 anterior column of gray matter 

 the nuclei of origin of the nerves 

 which supply the proximal mus- 

 cles are medially placed ; that 

 those for the distal muscles are 

 in general situated laterally. 

 If this is the case, the cells 

 connected with the shouldei 

 muscles will lie nearer the 

 middle of the anterior columr 

 of gray matter than those whicl 

 are connected with the hand 

 muscles. In cases where the; 

 forearm and hand, or the le 

 and the foot, are amputated, i 

 would appear that it is the pos 



tero-lateral column of cells that shows changes in consequence of its separation from th< 



muscles to which its fibres are distributed. 1 



Posterior median 

 septum 



Nucleus dorsalis 



Gray commissure 



Anterior median 

 fissure 



Antero-medial group 

 of motor cells 



Intermedio-lateral 

 column of cells 



Postero-medial group 

 of motor cells 



FIG. 469. SECTION THROUGH THE EIGHTH THORACIC SEGMENT OF THE 

 SPINAL MEDULLA. (To a large extent founded on Plates in 

 Dr. Bruce' s Atlas.) 



Posterior lateral furro 



Posterior column i 

 gray matter 



\ 



Intermedio-lateral Cell-column. The intermedio-lateral cells form a long slende 

 column which extends throughout the entire thoracic region of the medulla in th 

 lateral column of gray 

 matter. It is also pro- ^\ 



longed downwards into ^ 



the first and second lum- 

 bar segments, where it dis- 

 appears. In transverse sec- 



f c t i j i i Posterior median 



tions through the spinal septum 



medulla this cell -group 

 presents a very character- 

 istic appearance, because 

 the cells which compose 

 it are small and are closely 

 packed together. Al- 

 though these cells, as a 

 continuous column, are 

 restricted to the region 

 indicated, it should be 

 noted that the same group 

 of cells reappears above, 

 in certain of the cervical 

 segments, and also in the 

 third and fourth sacral 

 segments. From these 

 cells very fine fibres arise 

 and leave .the spinal 

 medulla, intermingled 

 with the motor fibres of 

 the anterior nerve-roots ; they pass into the sympathetic ganglia, of which th< 



Gray 

 commissure 



Anterior median 

 fissure 



Postero-lateral group 

 of cells 



Antero-medial 

 group of cells 



Central group 

 of cells 



An tero-lateral 

 group of cells 



FIG. 470. SECTION THROUGH THE THIRD LUMBAR SEGMENT OF T: 

 SPINAL MEDULLA TO SHOW THE GROUPING OF THE MOTOR CELI 

 (To a large extent founded on Plates in Dr. Bruce's Atlas.) 



1 Those who seek further information regarding the grouping of the ventral cells of the medulla n 

 with advantage study Dr. Alexander Bruce's Atlas of the Spinal Cord. 



