The M1 segment gives origin to the LLAs as it courses under the anterior perforated substance to emerge on the limen insulae. The number of LLAs can vary from only 1 to up to 15 ¹⁾.

These arteries supply the basal ganglia and internal capsule, but in cases of large tumors, they can be a source of vascular supply to the insula along with the M2–M3 short perforating branches. Early identification of the LLAs is key to avoid ischemic injury to the medial structures. Early dissection of the proximal M1 segment allows the surgeon to follow the artery and to identify the most lateral LLAs.

These LLAs represent the most medial limit of insular glioma surgery resection