The middle cerebral artery can be classified into 4 parts:
M1Segment : Called as Sphenoidal Segment, due to its origin and loose lateral tracking of the sphenoid bone. It is also called as the Horizontal Segment. Starts at the point of carotid bifurcation and ends at Limen Insulae.
M2 segment : Extending anteriorly on the insula, this segment in known as the Insular Segment. It is also known as the Sylvian segment. The MCA branches may bifurcate or sometimes trifurcate into trunks in this segment .
M3 segment : This segment is also called Opercular Segment and extends laterally exteriorly from the insula towards the cortex.
M4 Segment : Called Cortical Segment. These begin at the external to the Sylvian fissure and extend distally away on the cortex of the brain.
