Morphologic Variations of end Trunks of M1 Segment of Middle Cerebral Artery

The middle cerebral artery is divided into four segments: proximal M1, insular M2, opercular M3 and cortical M4.M1 extends from the bifurcation point of ACI at ACA and ACM to the insula threshold, laterally from chiasma opticum, laterallyfrom tractus opticus and caudally from trigonum olfactorium, directed laterally, dorsally and rostrally. Early division of the M1segment into the final trunk is possible at any of the first points of the limb insulae.Material and methods: The study of the micromorphological and morphometric characteristics of the M1 segment was performedin 25 brain (50 ACM preparations) obtained from autopsy of both sexes of different ages without pathological changes. For theremoval of the brain from the skull we used the usual technique of obduction.Results: This segment was arch-shaped, in 32 (64%) arteries, rarely S-shaped, in 12 (24%) arteries, much less straight alignment,in 6 (12%) arteries. The average length of the M1 segment of the S shape was 20.6 ± 3.31mm, with a 19.8 mm 4.41mm arch shape,while the straight shape was 16.9 ± 3.62mm. The average S-shaped diameter was 2.7 ± 0.51 mm, arched 2.6 ± 0.47 mm, straightform 2.6 ± 0.36 mm. Variations of M1 branching were: common in 38 cases, early branching in 12 cases, joint trunk with corticalbranch in 9 cases, lateral cortical branch in 21 cases, final bifurcation in 24 cases, final trifurcation in 13 cases, duplication in1 case and M1 accessory in just 1 case.Conclusion: True bifurcation refers to the division of the M1 segment into two final trunks. In cases where the strong jointcortical branch trunk divides from segment M1, while dividing into two terminal trunk immediately after ACM knee formation,it is described as false branching of M1 segment into three terminal branches.