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Question 2

Which one of the following vessels supplies the leg area of primary motor and somatosensory cortex?

a. Superior cortical division of MCA
b. ACA
c. Inferior cortical division of MCA
d. Basilar Artery
e. PCA

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Answer to Question 2

Correct Answer:

b. ACA

Additional Information:

The anterior cerebral artery (ACA) arises from the internal carotid at nearly a right angle. It sends deep penetrating branches to supply the most anterior portions of the basal ganglia. It then sweeps forward into the interhemispheric fissure, and then runs up and over the genu of the corpus callosum before turning backwards along the corpus callosum. As it runs backwards it forms one branch that stays immediately adjacent to the corpus callosum while a second branch runs in the cingulate sulcus (just superior to the cingulate gyrus). To summarize, the ACA supplies the medial and superior parts of the frontal lobe, and the anterior parietal lobe.

ACA Supplies These Key Functional Areas

septal area
primary motor cortex for the leg and foot areas, and the urinary bladder
additional motor planning areas in the medial frontal lobe, anterior to the precentral gyrus
primary somatosensory cortex for the leg and foot
most of the corpus callosum except its posterior part; these callosal fibers enable the language-dominant hemisphere to find out what the other hemisphere is doing, and to direct its activities

The short anterior communicating artery joins the two anterior cerebral arteries. It may allow collateral flow into the opposite hemisphere if the carotid artery is occluded on either side.