100 THE NERVOUS SYSTEM 



Proprioceptive Paths to the Cerebellum. According to the researches of 

 Marburg (1904) and Bing (1906) the spinocerebellar tracts are concerned with 

 the transmission to the cerebellum of afferent impulses from the muscles, joints, 

 and tendons, which remain, however, at a subconscious level (Dejerine, 1914). 

 We may, therefore, appropriately consider these paths at this time. 



The dorsal spinocerebellar tract (fasciculus spinocerebellaris dorsalis, direct 

 cerebellar tract of Flechsig, fasciculus cerebellospinalis) is a well-defined bundle 

 at the surface of the lateral funiculus just ventral to the posterior lateral sul- 

 cus (Figs. 72, 78). In cross-section it has the form of a flattened band, situated 

 between the periphery of the cord and the lateral corticospinal tract. It begins 

 in the upper lumbar segments and is prominent in the thoracic and cervical 

 portions of the cord. It consists of uniformly large fibers, which take origin 

 from the cells of the nucleus dorsalis of the same side. This nucleus forms a 

 prominent feature of the sections through the thoracic portion of the cord, but 

 is not found above the seventh cervical nor below the second lumbar seg- 

 ments. A conspicuous bundle of myelinated collaterals from fibers of the 

 fasciculus cuneatus run to this nucleus (Fig. 56) where their arborizations form 

 baskets about the individual cells of the nucleus. The fibers arising from the 

 cells of the nucleus dorsalis run laterally to the periphery of the lateral funiculus 

 of the same side, where they turn rostrally and form the dorsal spinocerebellar tract. 

 We will follow this tract into the brain in a latter chapter. Here we need only 

 say that it reaches the cerebellum by way of the restiform body (Fig. 235). 



The ventral spinocerebellar tract constitutes the more superficial portion of 

 a large ascending bundle of fibers, known as the fasciculus anterolateralis super- 

 ficialis or Gower's tract, which also includes the spinotectal and lateral spino- 

 thalmic tracts (Fig. 72). It is situated at the periphery of the lateral funiculus 

 ventral to the tract we have just considered. It is said to consist of fibers which 

 arise from the cells of the posterior gray column and intermediate gray matter of the 

 same and the opposite side (Page May, 1906; Dejerine, 1914). In a subsequent 

 chapter we will trace these fibers by the way of the medulla, pons, and an- 

 terior medullary velum to the cerebellum (Fig. 235). 



From what has been presented above it will be apparent that collaterals 

 and terminal branches of dorsal root fibers, doubtless of the proprioceptive 

 group, enter into synaptic relations with certain intraspinal neurons, the axons 

 of which run to the cerebellum by way of the ventral and dorsal spinocerebellar 

 tracts. The entire path from periphery to cerebellum therefore consists of two 

 neurons with a synaptic interruption in the gray matter. 



