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INTRODUCTION

In this chapter, we will review cerebrovascular anatomy, different types of strokes, and how they present with various signs and symptoms and review their treatment. CT and MRI images are presented to provide examples that may also be seen on the wards and on the shelf exam.

ARTERIAL BLOOD SUPPLY TO THE BRAIN

The blood supply to the brain, like every other organ, has its roots in the aorta. Branches give rise to the anterior and posterior circulations (Fig. 4-1).

FIGURE 4-1.

Blood supply to the brain—anterior circulation (common carotid arteries) and posterior circulation (vertebral arteries). Anastomotic channels between the middle and anterior cerebral arteries, and the middle and posterior cerebral arteries are depicted. The left side of the circle of Willis is shown: anterior communicating artery (purple; unlabeled), posterior communicating artery, and posterior cerebral artery. Reproduced with permission from Martin JH, eds. Neuroanatomy: Text and Atlas, 5th ed. New York: McGraw Hill; 2021.

Anterior circulation derives blood from the bilateral internal carotid arteries and supplies blood to most of the cerebral hemispheres, including the frontal lobes, parietal lobes, lateral temporal lobes, and anterior part of deep cerebral hemispheres (Figs. 4-2A and 4-2B).

  • Begins with the internal carotid arteries (external carotid arteries are extracranial) which migrate up the neck, through the skull and end in the circle of Willis (Fig. 4-3).

    • The circle is completed with smaller (but still very important) communicating arteries. The anterior communicating artery connects left and right anterior cerebral arteries while the posterior communicating artery is important for connecting the anterior circulation to the posterior circulation.

  • The anterior cerebral arteries (ACA) supply the most medial, frontal, and rostral parts of the cortex.

  • The middle cerebral arteries (MCA) supply the lateral cortices, including the frontal, parietal, and superior temporal lobes.

image   KEY FACT

ACA strokes often result in weakness of the contralateral leg.

image   KEY FACT

Four arteries bring blood to the brain, two common carotid arteries and 2 vertebral arteries.

image   KEY FACT

MCA strokes often are some of the most debilitating as they affect large areas of cortex.

FIGURE 4-2A.

Cortical distribution of cerebral arteries (anterior cerebral arteries, middle cerebral arteries, and posterior cerebral arteries). Reproduced with permission from Martin JH, eds. Neuroanatomy: Text and Atlas, 5th ed. New York: McGraw Hill; 2021.

FIGURE 4-2B.

Arterial supply of the subcortical white matter and internal capsule. Different dorsoventral levels of the internal capsule and limbs receive their arterial supply from different cerebral arteries. The dashed line indicates the plane of the horizontal section in ­Figure 4-2A. The territories supplied by each cerebral artery are shown. Reproduced with permission from Martin JH, ...

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