78 LABORATORY OUTLINE OF NEUROLOGY 



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 

 sections (see references under required drawings Section 62; 

 also Bailey ('16), Fig. 354, p. 524; Gray ('18), Fig. 696, p. 781; 

 Herrick ('18), Figs. 71, 75, and 86, and the discussion in Chaps. 

 IX and XI; Johnston ('16), Chap. XI; Morris ('14), Fig. 647, 

 p. 821, pp. 931, 932, Fig. 661, p. 837, Fig. 663, p. 839; Quain 

 ('09), Vol. ,3, Pt. 1, Fig. 150, p. 136; Rauber-Kopsch ('12), 

 Fig. 226, p. 281; Villiger ('12), Fig. 162, p. 175). 



88. Correlation fibers of the medulla oblongata. Afferent 

 nerve-fibers enter the medulla oblongata by the sensory roots of 

 the V to X cranial nerves and by certain tracts from the spinal 

 cord. Some of these fibers effect secondary connections with 

 the cerebellum as described below; some of the other connec- 

 tions are as follows: 



The peripheral general cutaneous fibers from the head are 

 discharged into the chief sensory and spinal V nuclei. The 

 axons of the neurons of these nuclei in part connect with the 

 various motor nuclei of the brain-stem for local reflexes, and in 

 part ascend to the thalamus through the trigeminal lemniscus, 

 as already mentioned. 



The central connections of the general proprioceptive fibers 

 of the head are unknown. Probably the mesencephalic V 

 nucleus is related to this system. 



The special proprioceptive fibers from the labyrinth are re- 

 ceived by the vestibular nuclei, as already described ; the axons 

 of these cells reach the various motor nuclei of the bulb, the 

 cerebellum (through the vestibulo-cerebellar . tract) and the 

 spinal cord (through the vestibulo-spinal tract) . The fascicu- 

 lus longitudinalis medialis is an important correlation tract 

 for this system (see Section 92). 



The chief central pathway from the cochlear nuclei is the 

 lateral lemniscus already studied ; but in addition to this there 

 are manifold reflex connections between these nuclei, the nuclei 

 of the trapezoid body, the superior olives, the nuclei of the 

 lateral lemniscus, and the inferior colliculus on one hand and 

 the motor nuclei of the bulb and spinal cord on the other hand. 

 The spinal connection is chiefly through the tecto-spinal tract 

 of the cord (Herrick ('18), Fig. 59). 



