662 



THE CEREBRUM 



(6) The anterior commissure connects the olfactory and certain portions of the 

 temporal lobes. It pursues a course through the anterior wall of the third ventricle 

 anterior to the pillars of the fornix. 



FIG. 331. LATERAL VIEW OP A HUMAN HEMISPHERE, SHOWING THE BUNDLES OF ASSO- 

 CIATION FIBERS. 



A, A, Between adjacent gyri; B, between frontal and occipital areas; C, between 

 frontal and temporal areas, cingulum; D, between frontal and temporal areas, fasciculus 

 uncinatus; E, between occipital and temporal areas, fasciculus longitudinalis inferior J 

 C. N, caudate nucleus; O.T, thalamus. (After Starr.) 



FIG. 332. DIAGRAM OF ASSOCIATION, COMMISSUEAL, AND PROJECTION FIBERS OF BRAIN. 

 A, Corpus callosum; B, anterior commissure; C, basal ganglia; D, endings of oom- 

 missural fibers; E, sensory cortex; M, motor cortex; F, endings of association fibers from 

 motor cortex (collaterals of projection-fibers) ; G, ending of association-fibers from 

 sensory center; H, projection-fibers from motor cortex passing to spinal centers; /, 

 projection-fibers from sensory cortex; a, b, c, collaterals. (Adapted from Cajal.) 



(c) The hippocampal commissure is formed in the hippocampus of one side and 

 ends almost wholly in the same structure of the opposite side. It is closely con- 

 cerned with the sense of smell. 



Mode of Development of the Cerebrum. In early embryonic 

 life the nervous system first presents itself as a dorsal tube, known as 



