The cistern is subdivided into three compartments: the superficial opercular compartment (SOC) (most superficial), deep opercular compartment (DOC) (intermediate), and cisternal compartment (CC) (deepest). The SOC contains the superficial MCV, and distal branches of the MCA; the DOC contains the M3 segment of the MCA; the CC contains the M1 and M2 segments of MCA, and the deep MCV.[4]