130 Neurological Technique 



Note the increase in the area of the cross-section of "pyra- 

 midal fibers" occurring in the pons as compared with those in 

 section 8. Explain the change in the shape of the section and 

 the contraction of the ventriculus quartus. What are the rela- 

 tive positions in the section of the sensory (ascending) fiber 

 bundles and the descending fiber bundles ? What is the brach- 

 ium conjunctivum ? What is the occasion of the change in the 

 name of the radix N. trigemini ? 



(1!^) Mesencephalon. 



Section 11, to pass at the immediate upper border of the 

 pons and through the inferior corpora quadrigemina (coUiculi 

 inferiores). The plane will slant backward slightly. 



Draw, giving special attention to the following structures : 



Fossa interpeduncularis, basis pedunculi, and substantia nigra. 



Lemniscus medialis and lateralis, fasciculus longitudinalis 

 medialis, radix descendens N. trigemini, and decussatio brachii 

 conjunctivi. 



Aqueductus cerebri (Sylvii), stratum griseum centrale, 

 nucleus N. trochlearis, stratum zonale, and nucleus colliculi 

 inferioris. 



What must be the course of the radices nervorum troch- 

 learum ? What fasciculi are contained in the basis pedunculi ? 

 What is the significance of the decussatio brachii conjunctivi ? 

 What is the aqueductus cerebri ? 



Section 12, to pass through the region of the emergence of 

 the Nn. oculomotorii and through the superior corpora quadri- 

 gemina (colliculi superiores) Will involve the corpus pineale. 



Draw, paying special attention to the following : 



Basis pedunculi, substantia nigra, fasciculus longitudinalis 

 medialis, lemniscus, and radix descendens N. trigemini. 



Aqueductus cerebri, stratum griseum centrale, nucleus N. 

 oculomotorii, and fila radicularia N. oculomotorii. 



Nucleus ruber (tegmenti), brachium quadrigeminum inferius, 

 and fibers of the commissura posterior. 



Colliculi superiores, corpus geniculatum mediale, tractus 



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