742 



THE XERVOUS SYSTEM 



(fig. 440a). Its fibres are processes of nerve-eells situated in tlie veniuform 

 process and the lateral lobe of the cerel)ellunr, they descend to the cord through 

 the middle peduncle of the cerebellum, and througln the restiform body. 



The ascending tracts of the antero-lateral column. — The dorso-lateral 

 or direct cerebellar tract occujnes the tlorsal i)art of tlie periphery of the cord on 

 the outer side of the crossed pyramidal tract, extending from the tip of the posterior 

 cornu to the antero-lateral ascending and descending tracts (fig. 440a). It separates 

 tlie crossed pyramidal tract from the surface, except in the lower dorsal region, 

 where the pyramidal fibres intervene l)etween it and Lissauer's column. Its fibres 

 are processes of some of the cells of Clarke's colunm, and they terminate in rami- 

 fications in the cerebellum, to which they jtass by the restiform body. 



The antero-lateral ascending cerebellar tract occupies an area in front 

 of the crossed pyramidal tract extending forwards to the region of tlie anterior 

 nerve-roots. Its' fibres are mingled with those of the descending antero-lateral tract, 



Fig. 440a.— Diagram of the Tracts of the Spinal Cord and of the Deep Oricuxs ok 



THE Spixal Nerves. 



BURDACWS COL. 



SOLITARY CELLS 



CLARKE'S COL. 

 GOLL'S COMMA 

 COL. TRACT 



POSTERIOR 

 ROOT 



POSTERIOR 

 ROOT 

 GANGLION 



LISSA UER'S COL. 

 DIRECT CERE- 

 BELLAR TRACT 



DIRECT PY- 

 RAMIDAL TRACT 



DESCENDING 

 ANTERO- 

 LATERAL 

 CEREBELLAR 

 TRACT {red) 



ASCENDING 

 ANTERO- 

 LATERAL 

 CEREBELLAR 

 TRACT {blue) 



ANTERIOR NERVE- 

 ROOT 



CENTRAL CELL 

 GROUP 



MESIAL CELL GROUP 

 ANTERIOR COMMISSURE 

 DIRECT PYRAMIDAL TRACT 



but they have a more limited anterior extension and they occupy a broader area 

 posteriorly; they are processes of nerve-cells of the cord and possibly of the cells of 

 the posterior cornu. They pass upwards through the reticular formation of the 

 medulla and pons; some reach the cerebellum by the superior peduncle and others 

 join the fillet. 



Lissauer's column is a small Inmdle of small fibres situated at the a})ex of 

 the posterior cornu dorsal to the crossed iiyramidal and direct cerebellar tracts. It 

 consists of the small fibres from the lateral parts of tlie posterior nerve-roots which 

 are passing upwards to terminate in the grey matter of higher segments of the 

 cord. 



The antero-lateral ground bundle embraces the anterior cornu and the outer 

 side of the l)ase of the jiosterior cornu (fig. 440a); it represents all the antero-lateral 

 column not included in the previously mentioned tracts, and it consists of ascend- 

 ing and descending commissural fibres passing between different segments of the 

 cord. 



