Is There a Superior Occipitofrontal Fasciculus? A Microsurgical Anatomic Study

OBJECTIVE: Using a fiber-dissection technique, our aim was to expose and study the myelinated fiber bundles of the brain to achieve a clearer conception of their configurations and locations. During the course of our study, the superior occipitofrontal fasciculus became the focus of our interest. Many publications have defined this as a bundle of association fibers, located between the corpus callosum and the caudate nucleus, that connects the frontal and occipital lobes. By examining this area using fiber dissection, we realized that the descriptions of the anatomy are inadequate; thus, we focused on the elucidation of the anatomic structures of this region and, in particular, that known as the superior occipitofrontal fasciculus. METHODS: Twenty previously frozen, formalin-fixed human brains were dissected under the operating microscope using the fiber-dissection technique. RESULTS: On coronal sections of the brain, a structure on the superolateral aspect of the caudate nucleus usually has been identified as the superior occipitofrontal fasciculus. However, our fiber dissections revealed that this structure is the superior thalamic peduncle, that it is composed of projection fibers rather than association fibers, and that it does not interconnect the occipital and frontal lobes. CONCLUSION: The structures of the brain are better understood when the fiber-dissection technique is used to explore their configurations and locations. The resulting information is especially beneficial for planning strategies and tactics of neurosurgical procedures.