74 LABORATORY OUTLINE OF NEUROLOGY 



among neurologists regarding the nerve-roots by which taste- 

 fibers reach the brain. The student should become familiar 

 with the various theories (see Cushing ('03), Herrick ('15), Fig. 

 115, and the accompanying discussion). 



86. Visceral efferent system. — In the microscopic sections 

 identify and draw the dorsal motor X nucleus under the ala 

 cinerea. See Section 62 (4) and Herrick ('15), Figs. 71 to 74 and 

 114. This is the general visceral efferent nucleus of the vagus. 

 The general visceral efferent nuclei of the IX and VII nerves are 

 respectively the inferior and superior salivatory nuclei (see Her- 

 rick ('15), Figs. 71, 73, and 114). These are not easily identified 

 in the sections. Identify also the nucleus ambiguus (Herrick 

 ('15), Figs. 71 to74and 114) and the chief motor nuclei of the VII 

 and V nerves. These are the nuclei of the special visceral motor 

 components. Look for fibers passing out from them into the 

 V, VII, IX, and X nerves. Extending from the nucleus 

 ambiguus downward into the spinal cord is the nucleus of 

 the XI nerve. In the upper levels of the cervical cord these 

 cells form the lateral gray column. Fibers may be seen pass- 

 ing directly lateralward from this nucleus into the spinal roots 

 of the XI nerve. 



Sections of the midbrain through the nucleus of the III nerve 

 will show a median group of cells of this nucleus, the nucleus of 

 Edinger-Westphal (see Herrick ('15), Fig. 71) which sends gener- 

 eral visceral efferent fibers to the ciliary ganglion. 



Visceral reflexes may be effected by short and very simple con- 

 nections between the afferent visceral sensory fibers terminating 

 in the nucleus of the fasciculus solitarius and the efferent visceral 

 fibers arising from the motor nuclei mentioned in the preceding 

 paragraphs. The neurones of the nucleus of the fasciculus soli- 

 tarius serve to connect these primary centers (see Herrick ('15), 

 Fig. 113). On the visceral efferent system in general, see John- 

 ston ('06), Chap. XII. 



87. Somatic motor nuclei. — This system is represented in the 

 III, IV, VI, and XII nerves. These nuclei and the root-fibers 

 arising from them should be drawn in the outlines of the sec- 

 tions (see references under required drawings Section 62; also 

 Bailey ('16), Fig. 354, p. 524; Herrick ('15), Figs. 71, 75, and 86, 

 and the discussion in Chaps. IX and XI; Johnston ('16), Chap. 



