372 LABORATORY MANUAL OF HUMAN ANATOMY 



(b) Pontocerebellar paths, from nuclei pontis to cortex of hemisphaerium 

 cerebelli of same and of opposite side. 



PATHS OF BRACHIUM CONJUNCTIVUM (0. T. SUPERIOR CEREBELLAK PEDUNCLE). 



(a) Paths from nucleus dentatus cerebelli through brachium conjunctivum 



to tegmentum of cerebral peduncle, there to decussate in large part 

 in the decussatio brachii conjunctivi, then to give off large numbers 

 of collaterals to the nucleus ruber, and finally, joining the fibres of 

 the lemniscus medialis, to end in the [ventro-] lateral nucleus of the 

 thalamus. There it connects with the thalamocortical path to the 

 central gyri (somaesthetic area). 



This path influences the spinal cord in at least two ways : 



(1) By collateral fibres which leave main axones soon after exit 

 from the cerebellum and pass down to the spinal cord (ramus de- 

 scendens of Ramon y Cajal). 



(2) Through the red nucleus which sends a path to the lateral 

 funiculus. 



(b) Path from spinal cord to cerebellum running in Gowers' tract upward 



to pons and corpora quadrigemina, then hooking around N. tri- 

 geminus and running, in velum medullare anterius, close to bra- 

 chium conjunctivum, to cerebellar vermis. 



Conduction Paths of Diencephalon and Telencephalon. 



I. PROJECTION FIBRE SYSTEMS. 



These are the fibre systems which connect the gray matter of the 

 telencephalon (pallium, nucleus caudatus, nucleus lentiformis, rhinen- 

 cephalon) with lower parts of the nervous system (thalamus, brain- 

 stem, spinal cord). 



(A) Ascending projection systems (corticopetal paths). 



(1) Uppermost neurone systems of general sensory path. The medul- 



lated axones pass from the cells in the [ventro-] lateral nucleus 

 of the thalamus, chiefly through the posterior third of the 

 capsula interna and corona radiata, to the cortex of the cen- 

 tral gyri (somaesthetic area) ; a few fibres go through or around 

 the nucleus lentiformis, and by way of the capsula externa to the 

 cortex. 



(2) Upper part of visual conduction path. The medullated axones pass 



from the cells in the nucleus corporis geniculati laterale and pul- 

 vinar thalami, through the radiatio occipitothalamica, to the 

 cortex about the fissura calcarina. 



(3) Upper part of auditory conduction path. The medullated axones 



pass from the cells in the nucleus corporis geniculati medialis and 

 nucleus colliculi inferior, by way of the posterior part of the 

 capsula interna, lateralward to the gyrus temporalis superior 

 (junction of third and fourth fifths), and adjacent gyri tem- 

 porales transversi. 



(B) Descending projection systems (corticofugal paths). 



(1) Pyramidal tract (fasciculi pyramidales] , from large pyramidal 

 cells of central gyri and lobulus paracentralis, through corona 

 radiata and through knee and anterior two-thirds of occipital 

 limb of capsula interna (head-movement fibres in front, arm 



