116 FLORENCE R. SABIN 



A. A group of fibres making up the main sensory tract to the cortex together 



with certain tracts associated with it by j)osition: 

 I. Seen from the mesial aspect — 



1. Lemniscus medialis and rubro-lenticular tract (or fasciculus 



lenticularis of Forel) 



2. Fasciculus gracilis and fasciculus cuneatus, — not modeled 



3. Tracts from no. 2, forming the lemniscus medialis, namely: 



(a) Decussatio lemniscorum 



(b) Fibrje arcutse internse 



4. Lemniscus lateralis 



5. Lemniscus superior 



6. Tract to the substantia nigra 



7. Tract to the nucleus hypothalamicus (Corpus Luysi) 



8. Tract connecting the nucleus colliculi inferioris with the center 



median of Luys 



9. Tract connecting the nucleus hypothalamicus of Luys with the 



globus pallidus 

 IL Seen from the lateral aspect — 



L Tract from the ventro-lateral nucleus of the thalamus to the upper 



third of the posterior central gryus 

 2. Lenticular nucleus to the same zone 



B. The fasciculus longitudinalis medialis and commissura posterior 



C. Miscellaneous: 



\. Fasciculus retroflexus of Meynert 



2. Corpus restiforme or inferior cerebellar peduncle, not modeled 



3. Brachium conjunctivum or superior cerebellar peduncle 



4. Rubro-pontal tract 



5. Formatio reticularis, — not modeled 



6. Cranial nerves, — not modeled 



7. Small bundle at root of optic nerve 



8. Optic fibres in relation to the lateral genticulate body 



9. Certain fibres associated with the substantia nigra, the nucleus 



hypothalamicus of Luys and the globus pallidus of the lenticular 

 nucleus. 



The lemniscus medialis is shown best in the three views of the 

 model from the mesial aspect, figs. 1, 3, and 4. The lemniscus begins 

 at the transition between the spinal cord and the medulla, at the 

 point where the decussatio lemniscorum crosses the middle line. 

 In the series studied, the posterior columns of the cord (no. 2, fig. 

 7), were medullated but were not modeled. The decussatio 

 lemniscorum is a small compact bundle (no. 3, fig .1), which begins 

 in the nucleus funiculi gracilis, curves around the edge of the 

 gray matter bordering the central canal, and crosses the middle 



