126 Neurological Technique 



Transfer the specimen from the preserving solution of for- 

 malin to water while the study is being made. Do not let it 

 become dry. 



In making the sections use a "brain knife" or a sharp knife 

 with a long thin blade. A section should be made at a single 

 stroke, if possible. 



{a) Rhombencephalon.— \t is supposed that the following 

 transverse sections are to be taken from the specimen, consist- 

 ing of the Rhombencephalon and Mesencephalon as detached 

 from the Prosencephalon in III, c, above. Use fig. I as a guide 

 in making the sections. 



Section 5, to pass transversely through the decussatio pyra- 

 midum. 



Draw, showing the form, position, and relations of the follow- 

 ing structures : 



Fissura mediana anterior and fissura mediana posterior (sep- 

 tum posterius of medulla spinalis). 



Pyramis, decussatio pyramidum, columna anterior, formalio 

 reticularis, substantia gelatinosa (Rolandi), canalis centralis, and 

 substantia grisea centralis. 



Funiculus gracilis, nucleus funiculi gracilis, funiculus cunea- 

 tus, nucleus funiculi cuneati, fibrae arcuatae internae, and lem- 

 niscus (fillet). 



Tractus spinalis N. trigemini (ascending root of the Vth 

 nerve), funiculi laterales, and fila radicularia N. accessorii. 



Carefully compare the drawing with that made from the sec- 

 tion through the pars cervicalis meduUae spinalis, and especially 

 note all modifications which have resulted in the transition of 

 medulla spinalis into medulla oblongata. Has the position of 

 the canalis centralis changed ? How has the septum posterius 

 now become the fissura mediana posterior ? Where are the 

 columnae posterior and anterior (dorsal and ventral horns)? 

 What is the relation of the decussatio pyramidum to the funi- 

 culi laterales ? What is the meaning of the nuclei funiculi 

 gracilis and funiculi cuneati? What is the lemniscus? 



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