TRACTS OF THE SPINAL CORD. 357 



of axonic processes of cells whose bodies are situated in the center 

 of the crescent and base of the anterior columna, chiefly on the 

 opposite side of the cord (v. Lenhossek). Most of the fibers of 

 the ascending anterior cerebello-spinal and spino-thalamic tract 

 cross near their origin through the white anterior commissure of 

 the cord. In the medulla, the tract ascends through the dorsal 

 part of the lateral area, sending collaterals to the inferior lateral 

 nucleus; it then continues, through the formatio reticularis of the 

 pons, to a point near the inferior quadrigeminal colliculus, where 

 the cerebellar part is bent backward under the brachium conjunc- 

 tivum, and enters the vermis cerebelli superior through the superior 

 medullary velum (Hoche). The spino-thalamic portion con- 

 tinues to the thalamus, sending some fibers to the quadrigeminal 

 colliculi (Mott) and others to the substantia nigra and lentiform 

 nucleus (Rossolimo). The anterior ascending cerebello-spinal 

 and spino-thalamic tract carries tactile, pain, and temperature 

 impulses. The triangular tract of Helwig (fasciculus olivaris) 

 is found on the surface near the middle of the area common to the 

 anterior cerebello-spinal tracts (Figs. 102 and 103). It descends 

 just lateral to the anterior nerve roots and may be traced to the 

 lumbar region, where its longest fibers end. It probably rises 

 in the olive of the medulla oblongata and is efferent in conduction. 

 The (posterior) cerebello-spinal tract (direct cerebellar) 

 (fasciculus cerebello-spinalis [posterior]) runs posterior to the 

 other cerebello-spinal tracts (Fig. 102). It is superficially located, 

 and in section extends from the middle of the lateral surface of 

 the cord back to the posterior lateral sulcus as far down as the 

 lumbar cord. Below the second lumbar segment its absence 

 allows the lateral pyramidal tract to come to the surface. The 

 (posterior) cerebello-spinal tract runs from the dorsal nucleus 

 (Clarki) of the cord to the superior worm of the cerebellum. 

 Its fibers are axones of vesicular cells hi that nucleus. In the 

 medulla, it forms a part of the restiform body. It conveys impulses 

 of the muscular sense, received, especially, from the viscera (?). 

 In the dorso-lateral part of the cerebello-spinal tract is a small 

 strand of fibers discovered by Horsley and Thiele in 1901, called 

 the spino-vestibular tract. It rises in the lumbo-sacral region 



