7 6 4 



A MANUAL OF PHYSIOLOGY 



two degenerated regions are seen, both at the surface of the cord, 

 one a compact, sickle-shaped area extending forwards from the 

 neighbourhood of the line of entrance of the posterior roots, 

 and the other an area of scattered degeneration, embracing 

 many intact fibres, and completing the outer boundary of the 

 column almost to the anterior median fissure. The compact area 

 is called the dorsal or direct cerebellar tract, or tract of Flechsig, the 

 diffuse area the antero-lateral ascending tract, or tract of Cowers, or 

 ventral cerebellar tract.* The dorsal cerebellar tract is dis- 

 tinguished by the large size of its fibres. It is only distinct in the 



FIRST CERVICAL. 



Antero-lateral 



ground-bundle 



(endogenous fibres) 



Direct pyramidal 



Antero-lateral ascending (Gowers') 

 (and antero-lateral descending) 



Crossed pyramidal 

 Direct or dorsal cerebellar 



Postero-external (Burdach's) 

 Postero-median (Coil's) 



SIXTH CERVICAL. 



SIXTH DORSAL. 



FIFTH LUMBAR. 



FIG. 314. DIAGRAMMATIC SECTIONS OF THE SPINAL CORD TO SHOW THE TRACTS 

 OF WHITE MATTER AT DIFFERENT LEVELS. 



dorsal and cervical regions of the cord. The tract of Lissauer, or 

 posterior marginal zone, is another small ascending tract at the 

 outer side of the tip of the posterior horn. It is made up of fine 

 fibres from the posterior roots which soon pass into the posterior 

 column. 



Descending Tracts. When the cord is divided, say in the 

 upper dorsal or cervical region, the following tracts degenerate 

 below the lesion : 



(i) A small group of fibres close to the antero-median fissure, 



* Some writers employ the more precise terms, dorsal and ventral 

 smo-cerebellar tracts. 



