TH1-: .SVV.Y.IL CORD 771 



spinal-cord neurones. It is composed of fibres of relatively very small diameter, and 

 it is one of the last fasciculi of the cord to Income medullated. 



Situated bet ween the superficial ventro-luteral cerebello-spinal fasciculus and the 

 lateral fasciculus proprius is an area which, in transverse section, by position, may 

 l>e referred to as the intermediate fasciculus (mixed lateral zone). It contains a 

 mixture of at least four varieties of axones: (1) It is said to contain descending 

 fibres from the cerebellum, to connect with the neurones of the spinal cord, prob- 

 ably the ventral root or motor neurones; (2) fibres from the red nucleus of the 

 tetrnientiuu (in the mcsencephalon). which probably form indirect cerebellar connec- 

 tions with the spinal-cord neurones; (3) fibres from Deiters' nucleus or the nucleus 

 lateralis of the vestibular nerve, in the upper portion of the medulla oblongata, thus 

 connecting the spinal-cord neurones with the auditory apparatus; (4) the most 

 lateral portion of the intermediate fasciculus, the region at one time included in 

 (lowers' tract, contains fibres from the corpora quadrigemina and the thalanms, 

 thus probably connecting the spinal cord with the optic apparatus as well as with 

 the auditory. These fibres are thought to terminate chiefly in contact with the 

 neurones of the fasciculi proprii, but to some extent directly with those giving origin 

 to the ventral or motor nerve-roots. A portion of the intermediate fasciculus has 

 been designated as Loeirenthal's tract. 



The anterior funiculus or column. The intermediate fasciculus is continued 

 ventrally and mesially across the line of exit of the ventral root axones, and thus into 

 tin' anterior funiculus. This portion is also mixed, but its axones of long course 

 connect somewhat different portions of the nerve axis from those connected by the 

 more lateral portion. According to the studies of Flechsig, von Bechterew, and 

 Held, this mesial portion contains fibres, both ascending and descending, which con- 

 nect the various levels of the grey substance of the spinal cord with the reticular 

 formation of the medulla oblongata. The levels to which they have been traced 

 contain the olivary nuclei, which are largely concerned in cerebellar connections, 

 and the nuclei of the tenth, ninth, eighth, seventh, and the spinal tract of the fifth 

 cranial nerves. Also they are probably associated with the nuclei of the eye-moving 

 nerves. This portion of the intermediate fasciculus also grades into and is mixed 

 with the axones of the ventral fasciculus proprius, as is its lateral portion with 

 the lateral fasciculus proprius. In other words, the fasciculi proprii proper, the 

 axones nearest the grey substance, serve for the intersegmental association of the 

 different levels of the grey substance of the cord, while the intermediate fasciculus 

 contains axones of longer course which serve to associate more distant levels of the 

 grey substance of the nerve axis that of the spinal cord with its upward continua- 

 tion into the brain-stem. 



The anterior marginal fasciculus (vestibulo-spinal tract, Loewenthal's tract) 

 forms the superficial boundary of the mesial portion of the intermediate fasciculus. 

 It is a narrow band, parallel with the surface of the cord, and extends mesially from 

 the mesial extremity of Gowers' tract (from Helweg's bundle) to the beginning of 

 the anterior median fissure. The axones belonging to it proper are descending from 

 the recipient nuclei of the vestibular division of the auditory nerve. Of these nuclei 

 it has been held by some investigators that only Deiters' nucleus (in the upper ex- 

 tremity of the medulla oblongata) gives origin to the axones of the anterior mar- 

 ginal fasciculus. Others agree with Tsc'hermak that the superior and more laterally 

 situated Bechterew's nucleus of the vestibular nerve also contributes axones to it. 

 More recent investigations have shown that, in part at least, the anterior marginal 

 fasciculus comes from the nucleus fastigii (roof nucleus) of the cerebellum. Since 

 many axones from both Deiters' and Bechterew's nucleus terminate in the nucleus 

 fastigii, the anterior marginal fasciculus is, in any case, a conduction path from the 

 vestibular portion of the auditory apparatus to the grey substance of the spinal 

 cord. The fasciculus is said to extend as far as the sacral region of the cord, its 

 axones terminating about the cells of the ventral horns. 



The ventral cerebro-spinal fasciculus (anterior or direct pyramidal tract), 

 as stated above, is the uncrossed portion of the descending cerebro-spinal system of 

 neurones. It is a small, oblong bundle, situated mesially in the anterior funiculus, 

 parallel with the anterior median fissure. Like the lateral cerebro-spinal fasciculus 

 (crossed pyramidal tract), its axones arise from the large pyramidal cells of the motor 

 or somaesthetic area of the cerebral cortex, and transmit their impulses to the neu- 

 rones of the ventral horns of the grey substance of the spinal cord, and almost 



