Vessels of the brain

The cerebral blood is supplied by two pairs of large arteries, departing from the arch of the aorta, - the carotid and vertebral arteries. The zone, which is carotid with carotid arteries, is also called the carotid or anterior vascular basin, and the zone, blood-supplying the vertebral arteries, is vertebro-basilar, or the posterior vascular basin.

The zone of bifurcation of the common carotid artery to the inner and outer carotid arteries is located near the angle of the lower jaw. The internal carotid artery should be upward, not giving up branches, before entering the cavity of the skull. After perforation of the dura mater, the first branch, the ocular artery (a. Ophthalmica), departs from it . It has already been mentioned that amaurosis fagax arises from the occlusion of this artery, the terminal branch of which is the central artery of the retina. Thus, loss of vision in one eye is characteristic of the pathology of the carotid artery or heart.

The internal carotid artery at the base of the brain is divided into the anterior and middle cerebral arteries. The anterior cerebral artery (PMA) follows the medial and blood supply to the inner part of the large hemisphere. Since the area of the cortex where the legs are represented is most medially located, the function of the leg suffers more than the functions of the hand or face when the PMA is occluded. Since cortical representation is contralateral to the body, stroke often affects the contralateral foci of the body: for example, in the right hemisphere, weakness occurs in the left extremities.

The middle cerebral artery (CMA) follows in the sylvian furrow from the base of the brain to the outer surface of the large hemisphere. In the sylvium furrow, penetrating vessels, lenticular ventricles, flow from the inner capsule, basal ganglia and part of the thalamus. The occlusion of these vessels causes lacunar syndromes, the most important of which is isolated hemiparesis ("purely motor insult"), most often caused by a small heart attack in the inner capsule. Small infarcts in the basal ganglia often remain asymptomatic.

Leaving the sylvian furrow, the SMA splits or rastraivaetsya on the branches, blood supplying the outer surface of the large hemisphere. Occlusion of these branches causes extensive wedge-like cortical infarcts, the clinical manifestations of which depend on whether they involve motor or somatosensory cortical areas. With the damage to visual radiance, there is a limitation of the visual fields. Violation of cognitive functions, for example, aphasia, is most often observed with occlusion of SMA branches.

With proximal occlusion of the SMA, the entire blood supply zone suffers, including both deep and cortical structures. In this case, loss of both motor and sensory functions develops involving the face, arms and legs. Even if the pool of PMA does not suffer, if the inner capsule is damaged, the function of the leg is disrupted. Occlusion of the carotid often leads to partial or complete involvement of the zone, blood-supplying SMA, due to the peculiarities of the collateral blood flow.

The posterior vascular basin is supplied with blood by the vertebral arteries, which merge into the basal bridge at the site of the medulla oblongata. Accordingly, each half of the medulla oblongata (and caudal part of the cerebellum) is supplied with only one vertebral artery. The basilar artery supplies the bridge with blood. At the midbrain level, it is again divided into two posterior cerebral arteries (ZMA). Both ZMA circulate the midbrain, following the back along the base of the large hemispheres. From the vertebral, basilar and posterior cerebral arteries, penetrating branches that supply blood to the brain stem.

Penetrating branches that depart from ZMA, blood supply the posterior parts of the cerebral hemispheres, including the medial parts of the frontal lobes and occipital lobes. The double blood supply of the central visual cortex prevents its damage during occlusion of one of the arteries, so that central vision with strokes involving the visual cortex often remains intact.

Syndromes, the nature of which does not correspond to the vascular anatomy of the brain, indicates that brain damage can be caused not by stroke, but by other diseases. Although brain tumors, primary or metastatic, can be acute, usually in these cases there are some other signs indicating that suddenly developed symptoms appeared against the background of a longer developing symptomatology. With a hemorrhage into the tumor or a rapid growth of the tumor, an insult-like acute development of symptoms is possible. A sudden development of symptoms, simulating stroke, is possible with multiple sclerosis. As with the tumor, and with multiple sclerosis, the methods of neuroimaging allow us to identify the characteristic changes that cause the sudden development of neurological symptoms.