356 THE SPINAL CORD. 



The descending anterior cerebello-spinal tract (fasciculus 

 descendens cerebello-spinalis anterior Marchi's, Tschermak's and 

 Loewenthal's column) together with the ascending anterior cere- 

 bello-spinal tract, occupies a thin peripheral area, broadest poste- 

 riorly, which extends from the anterior pyramidal tract outward 

 and backward, over the antero-lateral fasciculus proprius, to the 

 middle of the lateral surface of the cord (Figs. 102 and 103). Its 

 posterior border is in relation with the (posterior) cerebello-spinal 

 tract and the lateral pyramidal tract. The fibers of the two an- 

 terior cerebello-spinal tracts are mingled together; but the de- 

 scending fibers are found, chiefly, in the anterior and postero- 

 medial part of the common area and the ascending in the postero- 

 lateral part. The tract is almost completely relayed in the me- 

 dulla. The descending fibers, in the first stage, are axones from 

 the cortical cells of Purkinje in the cerebellum and from the nucleus 

 fastigii and perhaps the other cerebellar ganglia. They descend 

 to the nucleus of Deiters through the brachium pontis cerebelli. 

 There the greater number end and new fibers rise which continue 

 the tract down the cord. In all probability the cerebello-olivary 

 fibers in the restiform body, and the olivo-spinal fibers, forming 

 the tract of Helwig in the cord, should be included in the descend- 

 ing cerebellar tract. It terminates in the gray substance of the 

 spinal cord and directly or by the intervention of intrinsic spinal 

 neurones is connected with the motor cells of the anterior col- 

 umna. The descending cerebello-spinal tract forms one segment 

 of an indirect motor path; and, together with the intrinsic and 

 anterior columna neurones, it forms the efferent limb of a reflex 

 arc of muscular tonicity, coordination and equilibrium. Scattered 

 among the vestibolu- spinal fibers in the posterior part of the 

 anterior descending cerebello-spinal tract are descending fibers 

 from the thalamus and quadrigeminal colliculi which end in the 

 gray crescent. 



Ascending Anterior Cerebello-spinal and Spino-thalamic 

 Tract. (Fasciculus ascendens cerebello-spinalis anterior, Gowersi). 

 These form a single tract in the cord which is found chiefly in the 

 postero-lateral part of the area common to it and the descending 

 anterior cerebello-spinal tract (Figs. 102 and 103). It is composed 



