Association of the Middle Accessory Cerebral Artery With Bihemispheric Anterior Cerebral Artery and Median Artery of the Corpus Callosum.

As part of a microsurgical anatomy study of the recurrent artery of Heubner (RAH), we identified three rare vascular variants in a 45-year-old female cadaver: the right middle accessory cerebral artery (MACA), bihemispheric anterior cerebral artery (Bihem-ACA), and median artery of the corpus callosum (MACC). These anomalies were documented through meticulous dissection and detailed morphometric analysis, underscoring the value of cadaveric studies in elucidating complex cerebral vascular anatomy. The specimen was obtained within 24 hours postmortem. The cerebral arteries were injected with red latex and fixed using a standard protocol: initial perfusion with formaldehyde, followed by immersion in 10% formalin for a total fixation period of two months. Dissection was performed under a Carl Zeiss OPMI™ surgical microscope (Carl Zeiss Meditec AG, Jena, Germany) at 6x-40x magnification. Morphometric measurements were taken using a digital Mitutoyo vernier caliper (Mitutoyo South Asia Pvt. Ltd., New Delhi, India) with 0.01 mm resolution. During dissection, the right MACA was observed originating from the anterior communicating artery (ACoA), proximal to the junction of the A1 segments. It coursed posteriorly, running parallel to the right pre-communicating segment (A1) of the ACA and the sphenoidal (M1) segment of the middle cerebral artery (MCA). This artery measured 67 mm in length and 0.6 mm in diameter, with two perforating branches arising approximately 25 mm from its origin. The right A1 (d-A1) segment was dominant, measuring 14 mm in length, with a 1.5 mm diameter and an 8 mm outer perimeter, continuing distally as a single Bihem-ACA. This trunk extended 27 mm before bifurcating, with a proximal diameter of 1.7 mm and an outer perimeter of 9 mm. In contrast, the left A1 segment was hypoplastic, measuring 16.72 mm in length, 1 mm in diameter, and 5.5 mm in outer perimeter. The MACC originated from the left A3 segment of the ACA and measured 2.1 mm in diameter and 40 mm in length. It gave rise to two right cingulate-callosal branches (0.5 mm and 0.4 mm in diameter, respectively) directed toward the callosal sulcus and cingulate gyrus. These findings highlight an unusual combination of vascular variants not commonly observed together in a single individual. Recognizing such configurations is crucial for surgical planning, particularly in procedures involving the interhemispheric fissure, anterior communicating complex, and corpus callosum. Enhanced anatomical knowledge of these rare variants supports safer neurosurgical interventions and improves intraoperative decision-making in cerebrovascular procedures.