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The secret of the middle cerebral artery: Why is it the centerpiece of the brain's blood supply?
The middle cerebral artery (MCA) is one of the three main cerebral arteries that supply blood to the brain. This artery arises from the internal carotid artery and then enters the Sylvian fissure, subsequently branching to many areas of the lateral cerebral cortex. In addition to the cerebral cortex, the middle cerebral artery also supplies blood to the anterolateral temporal lobe and insular cortex. The middle cerebral arteries on the left and right sides extend from the trifurcation of the internal carotid artery and are connected to the anterior cerebral artery and the posterior communicating artery, which in turn connects to the posterior cerebral artery. It is noteworthy that the middle cerebral artery is not part of the circle of Willis.
Structure
The middle cerebral artery is divided into four segments, which are named according to the area they supply rather than the order of their branches, which can vary:
・M1: The petrous segment, which runs along the adjacent petrous bones, is also called the horizontal segment, although this can be misleading because it may run downward, parallel, or backward. .
・M2: Insular segment, extending to the front of the insula, also called the Sylvian segment when including the surrounding segment.
・M3: The encircling segment extends from the insula to the cortex.
・M4: These thinner cortical segments irrigate the cortex, starting at the outer edge of the Sylvian fissure and extending toward the distal end of the cerebral cortex.
Function
The area supplied by the middle cerebral artery includes most of the lateral side of the cerebral hemisphere; except for the upper one inch of the frontal and parietal lobes (which are supplied by the anterior cerebral artery) and the lower part of the temporal lobe. The superior portion of the middle cerebral artery supplies the lateral inferior frontal lobe (Broca's area, responsible for language expression), while the inferior portion supplies the lateral temporal lobe (Wernicke's area, responsible for language comprehension). The deep branches supply blood to the basal ganglia and internal capsule.
Clinical significanceBlocking
Occlusion of the middle cerebral artery results in middle cerebral artery syndrome, which may manifest itself in the following defects:
・Paralysis or weakness of the opposite side of the face and arm.
・Loss of sensation on the side of the face and arms.
・Damage to the dominant hemisphere (usually the left) can cause aphasia (i.e. damage to Broca's or Wernicke's areas).
・Damage to the non-dominant hemisphere (usually the right hemisphere) can cause contralateral neglect syndrome, an inability to correctly locate objects on that side.
Conclusion
Both for its structural complexity and its critical role in brain function, the middle cerebral artery is a blood vessel that cannot be ignored. By gaining a deeper understanding of this artery and its branches, we can better understand its importance to nerve function. In future studies, will we be able to reveal more mysteries of the cerebral arteries?
