Three-dimensional microsurgical anatomy of the basal aspect of the cerebrum: a fiber dissection study

J Neurosurg 144:690–702, 2026

This study presents a three-dimensional microsurgical fiber-dissection analysis of the basal aspect of the human cerebrum, detailing the spatial organization of commissural, projection, and association fibers and their relationships with subcortical nuclei, ventricles, and cortical landmarks. Using 10 formalin-fixed brains with layer-by-layer dissection and stereoscopic photography, the authors map tracts such as the ILF, UF, SS, cingulum, fornix, and connections around the amygdala and nucleus accumbens.

The findings emphasize surgical implications by clarifying trajectories and landmarks relevant to approaches like STIO and SCTT, illustrating a clinical case of hippocampal glioma resection with optic-radiation preservation, and proposing that 3D anatomical insight enhances safe, precise planning for medial temporal and basal lesions.

Objective Limited surgical exposure of the cerebral base makes basal fiber-tract injury a key risk; detailed 3D tract anatomy is needed to plan safer resections and support brain-function research.

Aim Mapped the topography of basal white-matter tracts and subcortical gray matter (including hippocampus, amygdala, and nucleus accumbens) and their relationships to cortex, ventricles, and nuclei.

Methods Performed Klingler-style layer-by-layer fiber dissection on 10 formalin-fixed human brains under ×6–×40 magnification, documenting each stage with stereoscopic 3D photography.

Key anatomy (basal tracts) Sequential basal dissection exposed U fibers, inferior cingulum (lower part), Li-Am fasciculus, SRF, and ILF; removing Li-Am/ILF revealed the temporal horn with the hippocampus medially.

Sagittal stratum layering The lateral wall of the atrium is layered (medial→lateral): ependyma, tapetum, IC-SL, optic radiations, posterior AC extension, IFOF, MdLF, posterior SLF/AF, U fibers, cortex—together forming the sagittal stratum.

ILF clarification The ILF was identified as a long association tract connecting the base of the temporal pole to the occipital base, located above the fusiform gyrus and beneath the sagittal stratum; “merging fibers” in lateral occipital base were distinguished from the temporal portion of the AF.

Amygdala connectivity The amygdala links to septal nuclei/hypothalamus/thalamus via the stria terminalis, projects to cortical regions via the uncinate fasciculus, and connects via additional pathways including amygdalofugal routes and the anterior commissure.

Surgical application (STIO case) A right hippocampal WHO grade 2 glioma was resected via a supratentorial-infraoccipital (STIO) approach; the fusiform gyrus was incised anterior to the basal turning point of the optic radiation to reach the lateral ventricle, and postoperative DTI confirmed optic-radiation preservation.