Microsurgical anatomy of the middle cerebral artery

✓ The microsurgical anatomy of the middle cerebral artery (MCA) was defined in 50 cerebral hemispheres. The MCA was divided into four segments: the M 1 (sphenoidal) segment coursed posterior and parallel to the sphenoid ridge; the M 2 (insular) segment lay on the insula; the M 3 (opercular) segment coursed over the frontoparietal and temporal opercula; and the M 4 (cortical) segment spread over the cortical surface. The Sylvian fissure was divided into a sphenoidal and an operculoinsular compartment. The M 1 segment coursed in the sphenoidal compartment, and the M 2 and M 3 segments coursed in the operculoinsular compartment. The main trunk of the MCA divided in one of three ways: bifurcation (78% of hemispheres), trifurcation (12%), or division into multiple trunks (10%). The MCA's that bifurcated were divided into three groups: equal bifurcation (18%), inferior trunk dominant (32%), or superior trunk dominant (28%). The MCA territory was divided into 12 areas: orbitofrontal, prefrontal, precentral, central, anterior parietal, posterior parietal, angular, temporo-occipital, posterior temporal, middle temporal, anterior temporal, and temporopolar. The smallest cortical arteries arose at the anterior end and the largest one at the posterior end of the Sylvian fissure. The largest cortical arteries supplied the temporo-occipital and angular areas. The relationship of each of the cortical arteries to a number of external landmarks was reviewed in detail.