The main functions of the brain and its main blood vessels

The human brain is a high-level central nervous system. As the "commander" of the human body, it directs all physiological activities of the human body, participates in limb activities, the generation of sensations, consciousness, spirit, language, learning, memory, intelligence, balance and other high-level neural activities. In terms of anatomical structure, the brain is also composed of different "departments", and different parts control different functions.

There are certain functional differences between the left and right brains of human beings. The language and thinking centers of human beings are generally located in the left hemisphere, which is called the dominant hemisphere. If these centers are damaged, language-related symptoms will occur. For example, if the motor language center is damaged, motor aphasia will occur. Although the muscles related to pronunciation are not paralyzed, the patient cannot speak. The right hemisphere also has special and important functions, such as spatial recognition, depth perception, touch, music appreciation, etc. Therefore, when different brain areas are damaged, different functional disorders will occur.

The human brain, like other organs, needs blood to provide oxygen and nutrients to maintain its functions. As the human brain is active, it needs more blood supply. The human brain, which accounts for only 2% of body weight, requires about 20% of the total blood supply of the body, so brain tissue is very sensitive to hypoxia. Once the blood supply is lost, the human brain will be more vulnerable to damage. The human brain is mainly supplied with blood by two groups of vascular systems: the bilateral carotid artery system and the vertebral artery system. The brain tissue is supplied with blood by four large arteries, namely the internal carotid artery system composed of the left and right internal carotid arteries and the vertebral-basilar artery system composed of the left and right vertebral arteries.

80%~90% of the blood supply to the brain comes from the internal carotid artery system, and 10%~20% comes from the vertebral-basilar artery system. The internal carotid artery system, also known as the anterior circulation system, supplies blood to the front 3/5 of the brain except for part of the temporal lobe and occipital lobe; the vertebral-basilar artery, also known as the posterior circulation system, supplies blood to the upper part of the spinal cord, the posterior 2/5 of the brain (occipital lobe, part of the temporal lobe, the posterior most of the thalamus and a small part of the hypothalamus), the brainstem and the cerebellum.