Figure 2.
A, Serial plottings of the cSpV showing the extent and localization of the injection of tracer in the three animals (RM75, RM76, RM77). The tracer injections primarily involved the superficial-most laminas I and II in all three cases, with minor spread into lamina III. The rostrocaudal extent of the injections ranged between 1 mm (RM77) and 1.5 mm (RM76). B, Drawings of cross sections through the brainstem at selected medullary, pontine, and midbrain levels, showing the location of labeled ascending fibers (in RM77). 4, Fourth ventricle; cp, cerebral peduncle; Cu, cuneate nucleus; DR, dorsal raphe nucleus; DV, dorsal motor nucleus of the vagus; eCu, external cuneate nucleus; mlf, medial longitudinal fasciculus; Gr, gracile nucleus; IO, inferior olivary complex; LR, lateral reticular nucleus; mcp, middle cerebellar peduncle; ml, medial lemniscus; PN, pontine nuclei; py, pyramidal tract; SA, sylvian aqueduct; SC, superior colliculus; SpV, spinal trigeminal nucleus; STN, solitary tract nucleus; V, principal trigeminal nucleus; VNC, vestibular nuclear complex; VR, ventral raphe nucleus; xbc, decussation of the brachium conjunctivum; XII, hypoglossal nucleus; xpy, pyramidal decussation.