ANAT 2646 The Blood Supply

ANAT 2646 The Blood Supply - The Blood Supply Medial View...

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The Blood Supply Medial View The Blood Supply Lateral View Blood transports oxygen and other nutrients necessary for the health of neurons, so a constant flow of blood to the brain must be maintained. According to Love and Webb,1992, the brain uses approximately twenty percent of the body's blood and needs twenty-five percent of the body's oxygen supply to function optimally. Blood flow in a healthy person is 54 milliliters per 1000 grams of brain weight per minute. There are 740 milliliters of blood circulating in the brain every minute. 3.3 milliliters of oxygen are used per minute by every 1000 grams of brain tissue. This means that approximately 46 milliliters of oxygen are used by the entire brain in one minute. During sleep, blood flow to the brain is increased, but the rate of oxygen consumption remains the same. Subclavian Artery The main artery of the body is called the aorta . It supplies blood to all parts of the body with the exception of the lungs. The aorta ascends from the heart and forms an arch, from which arise two subclavian arteries. Each subclavian has two main branches, the common carotid and the vertebral . Both of these carry blood to the brain. Each common carotid divides into an external carotid artery , which supplies blood to the face and an internal carotid artery which supplies the brain with blood. The external carotid is a fairly straight artery, so it is not prone to blockages due to the build up of cholesterol. Even if a blockage does occur, it would obviously not cause a stroke as this artery does not carry blood to the brain. 1
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The Internal Carotid Each internal carotid artery ascends along one side of the neck. They pass behind the ear into the temporal lobe and enter the subarachnoid space. Then, they run posteriorly to the medial end of the fissure of Sylvius where they bifurcate into two main branches, the anterior cerebral artery and the middle cerebral artery . As the internal carotids have many twists and turns, there are many places where plaque can build up, causing a blockage. Such blockages can be identified by sonogram (non-invasive), or by angiograms (invasive). Also, a sound called a bruit can sometimes be heard via stethoscope when a blockage exists. The anterior cerebral artery goes above the optic chiasm to the medial surface of the cerebral hemispheres. It arches around the genu (horn) of the corpus callosum (FitzGerald, 1996). It supplies blood to the medial cortex, including the medial aspect of the motor strip and the sensory strip. This means that damage to the anterior cerebral artery can cause sensory and motor impairment in the lower body. For example, a patient who has had a stroke affecting this artery may be incontinent or have unilateral paralysis from the hips on down. The anterior cerebral artery also delivers blood to some parts of the frontal lobe and corpus
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This note was uploaded on 11/23/2011 for the course ANAT 2646 taught by Professor Ronaldg.mayne during the Winter '11 term at Life Chiropractic College West.

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ANAT 2646 The Blood Supply - The Blood Supply Medial View...

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