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Middle cerebral artery

The Middle Cerebral Artery (MCA) is one of the three major paired arteries that supply blood to the cerebrum. It is the largest branch of the internal carotid artery and is the most commonly affected vessel in cerebrovascular accidents (strokes). The MCA courses laterally through the Sylvian fissure, supplying large portions of the lateral cerebral cortex, including areas responsible for motor, sensory, language, and auditory functions. Due to its extensive supply and superficial location, the MCA plays a critical role in neurological function and is frequently assessed in neuroimaging studies.

Synonyms

  • MCA

  • Sylvian artery

  • Arteria cerebri media (Latin)

Origin and Course

  • Origin: Arises from the internal carotid artery, just after its bifurcation from the common carotid artery.

  • Course:

    • Proceeds laterally from the internal carotid artery into the lateral (Sylvian) fissure.

    • Divides into several segments:

      • M1 (Sphenoidal or horizontal segment): Runs laterally, deep to the temporal lobe.

      • M2 (Insular segment): Turns superiorly within the insular cortex.

      • M3 (Opercular segment): Extends through the operculum.

      • M4 (Cortical segment): Branches over the surface of the lateral cerebral cortex.

  • Branches:

    • Lenticulostriate arteries (early deep branches to basal ganglia/internal capsule)

    • Cortical branches (to frontal, parietal, temporal lobes)

Function

  • Supplies blood to a large portion of the lateral convexity of the cerebral hemisphere.

  • Key regions supplied:

    • Primary motor and sensory cortex for face, hand, and arm.

    • Broca's and Wernicke’s areas (language areas, dominant hemisphere).

    • Auditory cortex.

    • Parietal and temporal association areas.

    • Parts of the basal ganglia and internal capsule via lenticulostriate arteries.

  • Clinical significance: Most common site for ischemic strokes, which may cause contralateral weakness, sensory loss, aphasia (if dominant hemisphere), and visual field defects.

MRI Appearance

  • MCA and its branches can be visualized using MR Angiography (MRA).

  • Normal: Seen as flow voids (dark linear or dot-like areas) on routine T2-weighted images.

  • Pathology: Acute MCA infarcts appear as areas of restricted diffusion on DWI/ADC sequences. Loss of flow void may indicate occlusion. Vessel caliber and flow changes are best seen on MRA.

CT Appearance

  • MCA is not directly visualized on non-contrast CT, but its location can be inferred.

  • CT Angiography (CTA): The artery and its branches are visualized with intravenous contrast, showing patency or occlusion.

  • Acute infarct: May see "hyperdense MCA sign" on non-contrast CT (indicative of acute thrombus within the vessel).

  • Late changes: Hypodensity in MCA territory indicating infarction; loss of gray-white matter differentiation; sulcal effacement due to edema.

MRI images

Middle cerebral artery (Sylvian artery) MRI axial TOF image

MRI images

Middle cerebral artery MRI T2 axial image

MRI images

Middle cerebral artery MRI T2 sagittal image

CT image

Middle cerebral artery (Sylvian artery) ct images