THE SENSORY PATHS 



529 



hW 



A medio-lateral root zone adjoins the posterior two-thirds of 

 the dorsal horns and contains the compact bundles of the posterior 

 nerve roots on their way to the grey matter. 



The comma tract of Schultze occupies the mesial side of the 

 middle third of Burdach's column and adjoins the lateral aspect of 

 the postero-internal column or tract of Goll. It is thought to con- 

 tain the short descending branches of incoming posterior nerve 

 root fibres, and perhaps also intrinsic or endogenous fibres which 

 pass up or down to connect neighboring segments of the spinal 

 cord. The medio-lateral zone together with the comma tract forms 

 the greater part of the middle root zone. 



The dorsal root zone contains, on its outer side, the fine ascend- 

 ing and descending fibres derived from the dorsal nerve roots 

 which form the tract of Lissauer. This bundle occupies a small 

 area in the lateral portion of the dorsal root zone. 



The mesial portion of the dorsal root zone includes a large area 

 in which are those posterior root fibres which pass obliquely up- 

 ward through the tract 

 of Burdach to a higher 

 level, where they enter 

 the tract of Goll (pos- 

 tero-internal column). 

 As a result of their 

 oblique direction, those 

 root fibres which enter 

 the lower segments of 

 the spinal cord will, 

 upon reaching the 

 tract of Goll, lie near- 

 est the median line; 

 those which enter high- 

 er spinal segments nec- 

 essarily arrive later in 

 the tract of Goll and 

 are thus forced to take 

 a more lateral position 

 in their further course 

 to the medulla ob- 



vW 

 aW 



FIG. 407. UPPER HALF OF LUMBAR ENLARGEMENT OF 



A FETUS 35 CM. LONG. 



a W, dorsal root zone (lateral portion) of dorsal funic- 

 uli (Lissauer's fasciculus) ; A, dorsal roots, partly med- 

 ullated ; h TF, dorsal root zone (medial portion) ; m W, 

 middle root zone ; PS, lateral pyramidal tract ; , dor- 

 sal root zone (most median part of medial portion) of 

 dorsal funiculi ; t>, ventral roots, medullated ; v W, ven- 

 tral root zone of dorsal funiculi. (After Flechsig.) 



longata. 



The group of dorsal root fibres which thus follows the tract of 

 Goll to the medulla oblongata ends by terminal arborizations about 



35 



