812 



THE NERVOUS SYSTEM 



to the cerebellum mesial to the brachium pontis. Here the restiform body is near- 

 ing completion, and the fibres now contained in it may be summarised as follows : 



(1) The fibres of the cerebello-spinal fasciculus (direct cerebellar tract) of the 



same side. 



(2) Fibres from the nuclei funiculi gracilis and funicuh cuneati of the same and 

 opposite side (external arcuate fibres). 



(3) Fibres to and from the inferior olives of the same and opposite side (cere- 

 bello-olivary fibres) . 



(4) Sensory cerebellar fibres from the nuclei of termination of the vagus, glosso- 

 pharyngeus, vestibularis, and trigeminus, and from the cells of the reticular for- 

 mation. 



(5) Descending fibres to the motor nuclei of these nerves, except that of the 

 trigeminus, and fibres descending into the intermediate and anterior marginal 

 fasciculi of the spinal cord, the latter being in large part interrupted by cells in the 

 nucleus of the vestibular nerve. 



The ascending fibres of the restiform body are distributed to the cortex of the ver- 

 mis, the nucleus fastigii, the nucleus dentatus, nucleus emboliformis, and nucleus 

 globosus. 



Very few if any of the fibres ascending the cord in Cowers' tract enter the cere- 



FIG. 605. DIAGRAM SHOWING THE RHOMBENCEPHALIC COURSE OF COWERS' TRACT AND THE 



DIRECT CEREBELLAR TRACT. 



CEREBELLO-SPINAL FASCICU- 

 L US (direct cerebellar tract ) 



, /: n. trim -j/- coyjr. -XCTI iv :v 



SUPERFICIAL ANTERO-LATER.AL 

 FASCICULUS (Gowers' tract) 



bellum by way of the restiform body. This tract (the superficial antero-lateral fas- 

 ciculus of the spinal cord) ascends the medulla, dispersed in the reticular formation, 

 and therefore in a more ventral position than that of the direct cerebellar tract. In 

 this position it becomes enclosed by the fibres of the pons, and so it passes upwards 

 around the lateral lemniscus to the brachium conjunctivum, and there turns back to 

 enter the cerebellum by way of the anterior medullary velum. Certain clinical 

 phenomena, probably purely psychological, have been alleged to indicate that some 

 of the fibres of Gowers' tract pass on to the cerebrum instead of turning in the med- 

 ullary velum to enter the cerebellum. 



The dorsal part of a transverse section through the upper part of the pons con- 

 tains the brachia conjunctiva (superior cerebellar peduncles) instead of the 

 restiform bodies or inferior peduncles. Instead of the cerebellum forming the roof 

 of the fourth ventricle, in this region the roof is formed by the anterior medullary 

 velum bridging the space between the two brachia conjunctiva. Adhering upon the 

 medullary velum is the lingula cerebelli the ventral extremity of the superior 

 vermis. This is the only portion of the cerebellum attached to this region. 



The lemniscus (fillet) is found more lateral than at the inferior border of the 

 pons, and is divided into the medial lemniscus and lateral lemniscus proper. The 

 lateral lemniscus has shifted dorsally until in this region it courses in the dorso- 



