Microsurgical anatomy of the fiber tracts and vascular structures lateral to the internal capsule

J Neurosurg 143:1068–1076, 2025

This microsurgical study maps white matter fiber tracts and vascular anatomy from the brain’s lateral surface to the internal capsule using perfused cadaveric specimens and Klingler fiber dissection. Key tracts (AF, SLF II/III, FAT, MdLF, UF, IFOF) and vascular elements (MCA segments, LSAs, LSVs, venous drainage groups) are described with measurements and surgical landmarks.

Findings emphasize trajectories relevant to Kocher’s point, the spatial relationships of LSAs/LSVs to the putamen and internal capsule, and implications for minimizing functional and vascular injury during neurosurgical approaches and revascularization procedures.

• Anatomical Focus: The study investigates the microanatomy of white matter fiber tracts and vascular structures lateral to the internal capsule, using fiber dissection and vessel perfusion techniques on human cadaveric brains.

• Key Structures: Major fiber tracts identified include the arcuate fasciculus (AF), superior longitudinal fasciculus (SLF), frontal aslant tract (FAT), middle longitudinal fasciculus (MdLF), uncinate fasciculus (UF), and inferior fronto-occipital fasciculus (IFOF); the main vascular structures are branches of the middle cerebral artery (MCA) and lenticulostriate arteries (LSAs), each accompanied by lenticulostriate veins (LSVs).

• Vascular Territories: Superficial arteries supply only the gray matter of the lateral brain surface, while deeper white matter and basal ganglia receive blood from LSAs originating from the M1 segment of the MCA; there is no direct communication between insular arteries and LSAs, with the external capsule marking their vascular boundary.

• Surgical Implications: Kocher’s point, a standard neurosurgical entry site, traverses the posterior middle frontal gyrus, SLF III, external capsule, and basal ganglia, avoiding major arteries, veins, and critical fiber tracts such as the AF and internal capsule, thus minimizing functional risk.

• Clinical Relevance: Understanding the course of LSAs and LSVs is crucial for safe neurosurgical procedures in the basal ganglia and insular region, as injury to these vessels can cause severe neurological deficits; the study provides anatomical evidence supporting the safety of the Kocher’s point approach.

• Functional Anatomy: The AF is essential for language by connecting Broca’s and Wernicke’s areas; the internal capsule is critical for motor and sensory information transfer between cortex and brainstem/spinal cord.