366 THE NERVOUS SYSTEM 



Somatic efferent red. 



All cerebellar connections not strictly proprioceptive brown. 



Other tracts black. 



PROPRIOCEPTIVE PATHS AND CENTERS (pp. 311-315) 



70. The cerebellum is the chief proprioceptive correlation center, and the restiform 

 body consists for the most part of proprioceptive afferent paths (Fig. 235). Note its 

 shape, position, and connections in all the gross specimens. In the left lateral half of 

 the sheep's brain follow it caudally by dissection, separating it from the other peduncles. 

 Cut and reflect the dorsal cochlear nucleus of the eighth nerve. Trace the restiform 

 body backward and note the accession of external arcuate fibers. At the level of the 

 inferior olive it receives the dorsal spinocerebellar tract. Trace this by dissection from 

 the restiform body obliquely across the upper end of the tuberculum cinereum and 

 then caudally along the ventral border of this elevation to the spinal cord. (See Figs. 

 87, 88, 104; pp. 143, 205.) 



71. Now take the sections of the medulla, locate the dorsal spinocerebellar tract 

 in each, and indicate its position in yellow on the right side of your outlines (p. 144). 

 Locate the external ar cute fibers (p. 139). From where do they come and where do they 

 go? Draw in yellow those belonging to the right peduncle. Locate in your sections 

 the oliwcerebellar tract, and with brown indicate in your outline the fibers running into 

 the right peduncle (Fig. 103). 



72. From your texts ascertain the course of the ventral spinocerebellar tract and 

 indicate its position in yellow on the right side of the outlines (Fig. 149; p. 157). 



73. Proprioceptive Path to the Cerebral Cortex. Indicate in yellow the terminal 

 portion of the right dorsal funiculi, and with yellow stipple the right nucleus gracilis 

 and nucleus cuneatus (Figs. 98, 99). Study the internal arcuate fibers and the medial 

 lemniscus, drawing the internal arcuate fibers from right to left and the medial lemniscus 

 on the left side (yellow). Where do the fibers of the medial lemniscus terminate? 

 What is the source and what the destination of the impulses which they carry? (See 

 Figs. 101, 103, 107, 108, 110, 114, 116, 235 and pp. 138, 312.) 



74. Locate the vestibular nuclei and indicate them with yellow stipple on the right 

 side of the outlines (Figs. 101, 103, 107, 108). Locate the vestibulocerebellar tract 

 (pp. 151, 188; Fig. 136). 



EXTEROCEPTIVE PATHS AND CENTERS (pp. 302-310) 



75. The Cochlear Nerve and its Connections. On the sheep's brain note the two 

 divisions of the acoustic nerve as well as the ventral and dorsal cochlear nuclei and the 

 trapezoid body (Fig. 87). Examine the cochlear nuclei and the striae medullares in the 

 human brain (Fig. 89). Locate the lateral lemniscus where it forms a flat band of 

 fibers directed rostrally and dorsally upon the lateral surface of the mesencephalon. 

 It occupies a triangular space dorsal to the basis pedunculi and rostral to the pons and 

 is superficial to the brachium conjunctivum (Fig. 88). 



76. Now take the section through the lower border of the pons and study the 

 cochlear nuclei, the stria medullares, and the beginning of the trapezoid body (Fig. 107). 

 In the section through the facial colliculus study the trapezoid body and the superior 



