1 1 2 Neurological Technique 



{c) The nervi spinales. i. Subdivisions: complete the expo- 

 sure of the medulla spinalis by continuing the opening of the 

 dura mater and arachnoidea along the entire dorsal mid-line. 

 Again lay the specimen straight, dorsal side up, and identify the 

 pars cervicalis with its intumescentia cervicalis (cervical enlarge- 

 ment) and its eight pairs of nerves (nervi cervicales); the pars 

 thoracalis with its twelve pairs of nervi thoracales ; the pars 

 lumbalis with its intumescentia lumbalis (lumbar enlargement) 

 and its five pairs of nervi lumbales ; and the pars sacralis with 

 its six pairs of nerves (nervi sacrales et coccygei). 



2. Radices nervorum spinalium : Note that each nerve is 

 formed by the fusion of its radix posterior (dorsal root) and its 

 radix anterior (ventral root), and that each radix before its 

 attachment to the medulla spinalis is broken up or subdivided 

 into a number of rootlets, fila radicularia. Passing from the 

 pars cervicalis to the pars sacralis, note the progressive increase 

 in the length of the radices. Where are the shortest and most 

 horizontal radices ? Explain the increase in length on the basis 

 of an unequal growth of the medulla spinalis and the columna 

 vertebralis. What is the cauda equina ? Sketch it. 



3. Ganglia spinalia : Remove the dura mater from about the 

 radices and ganglion spinale of a nerve, then clip the radices, 

 and, keeping in mind the orientation of the nerve, place it under 

 the dissecting lens and carefully separate the radices at their 

 junction in the region of the ganglion spinale. Which radix is 

 in more intimate connection with the ganglion ? What is the 

 behavior of the other radix ? Make a sketch showing the rela- 

 tions of both radices and attach their names. Tease one of the 

 radices and then tease the ganglion itself. What differences 

 are to be noted in the appearance of the tissue of the two ? Of 

 what is the ganglion composed ? What is the more exact rela- 

 tion of the ganglion to the radix observed above to be connected 

 with it ? 



(d) Medulla spinalis proper : What are the relative dimen- 

 sions of the pars thoracalis as compared with the partes cervi- 

 calis and lumbalis ? At the levels of what nerves, approximately. 



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