CEREBELLUM, PONS, AND MEDULLA. 235 



cells of the cortex terminate in these subcortical nuclei, and the 

 efferent path from the cerebellum is then continued by new 

 neurons. Thus, the fibers of the superior peduncles (brachium 

 conjunctivum) of the cerebellum arise chiefly from the dentate 

 nuclei, and only indirectly from the cortex. The anatomical 

 connections, afferent and efferent, between the cerebellum and 

 other parts of the nervous system are very complex and not 

 yet entirely known. Without attempting to recall all of these 

 connections, which will be found described in works upon anat- 

 omy or neurology, emphasis may be laid upon those which are 

 at present helpful in discussing the physiology of the organ. 



1. Connections with the Afferent Paths of the Cord.- Through the 

 inferior peduncles (restiform bodies) the cerebellum receives affer- 

 ent fibers from the spinal cord and the medulla. The cerebello- 

 spinal fasciculus undoubtedly terminates in the cerebellum, and 

 according to some observers the fibers of the posterior funiculi 

 after ending in the n. gracilis and n. cuneatus are also continued 

 in part to the cerebellum by nerve fibers passing by way of the 

 inferior peduncles. This latter view has, however, not found 

 confirmation in recent work, most authors believing that the 

 afferent fibers of the posterior funiculi all enter the lemniscus, 

 after decussating, and pass forward to the thalamus. Ascending 

 fibers arising in the reticular formation of the medulla and the 

 olivary nucleus may take this path to the cerebellum, and, on the 

 other hand, may make connections with the sensory tracts of 

 the cord or the sensory nuclei of the medulla. Another afferent 

 tract of the cord, that of Gowers (fasciculus anterolateralis super- 

 ficialis), ends in the cerebellum, in large part at least, forming a 

 part, in fact, of the cerebellospinal system. The nature of the 

 sensory impulses conveyed in this way to the cerebellum is not 

 entirely understood, but it seems certain that some of them, at 

 least, arise in the deeper tissues, the muscles and joints. This 

 tract and the similar tract of Flechsig, by forming an afferent con- 

 nection between the deep tissues and the cerebellum, present a 

 mechanism which may be used to explain the influence exercised 

 by the cerebellum upon muscular activity. 



2. Connections with the Vestibular Branch of the Eighth Cran- 

 ial Nerve. This branch, arising in the semicircular canals and 

 utriculus and sacculus, ends in the pons in several nuclei (Deiters', 

 Bechterew's) and also in the n. fastigii of the cerebellum. These 

 nuclei, in turn, are connected with other parts of the central 

 nervous system, but the details are not yet completely known. 

 The connections that have been most clearly established are 

 those made with the motor centers. Through the medial longi- 

 tudinal fasciculus these nuclei are connected with the motor 

 nuclei of the cranial nerves and with descending paths in the spinal 



