THE CORTEX AND MEDULLARY CENTER OF THE CEREBRAL HEMISPHERE 



299 



intervening sulci, and are accordingly often designated as arcuate fibers (Fig. 

 226). Others unite somewhat more widely separated gyri. The long association 

 fibers form bundles of considerable size, deeply situated in the medullary center 

 of the hemisphere, and unite widely separated cortical areas. There are five 

 of these which may be readily displayed by dissection of the human cerebral 

 hemisphere, namely, the uncinate, inferior occipitofrontal, inferior longitudinal, 

 and superior longitudinal fasciculi, and the cingulum. Another, known as the 

 fasciculus occipitofrontalis superior, is less easily displayed. 



The cingulum is an arched bundle which partly encircles the corpus callosum 

 not far from the median plane (Figs. 174, 226). It begins ventral to the rostrum 

 of the corpus callosum, curves around the genu and over the dorsal surface of 



Optk radiation External capsule and lentiform nucleus 



Corona radiata / Frontal lobe 



~--Fas. occipitofrontalis 



inferior 

 ~'Fas. uncinatus 



"-Temporal lobe 



Fig. 227. Lateral view of a dissection of a human cerebral hemisphere. The dorsal part 

 of the hemisphere has been cut away. On the lateral side the insula, opercula, and adjacent parts 

 have been removed. 



that commissure to the splenium, and then bends ventrally to terminate near the 

 temporal pole. It is closely related to the gyrus cinguli and the hippocampal 

 gyrus and is composed for the most part of short fibers, which connect the various 

 parts of these convolutions. 



The uncinate fasciculus connects the orbital gyri of the frontal lobe with the 

 rostral part of the temporal lobe. It is sharply bent on itself as it passes over 

 the stem of the lateral fissure of the cerebrtffii (Figs. 227, 228). The inferior 

 longitudinal fasciculus is a large bundle which runs through the entire length of 

 the temporal and occipital lobes (Fig. 226). It connects the occipital pole, 

 the cuneus, and other parts of the occipital lobe with the temporal cortex, ex- 

 tending as far forward as the temporal pole. According to Curran (1909) the 



