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circle of Willis

a ring of blood vessels on the underside of the brain, formed by links between branches of several major arteries—the basilar artery, internal carotid artery, anterior cerebral artery, anterior communicating artery, middle cerebral artery, posterior cerebral artery, and posterior communicating artery. By providing multiple pathways for blood circulation, this arrangement ensures the continuous flow of oxygenated blood to the brain in the event a supplying artery becomes blocked or constricted as a result of an injury, disease, or other condition. Also called arterial circle. [Thomas Willis (1621–1675), English anatomist and physician who was the first to illustrate this area definitively and provide a description of its function]

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Psychology term of the day

March 17th 2025

dominance–subordination

dominance–subordination

a form of social relationship within groups with a leader or dominant member who has priority of access to resources over other, subordinate members of the community. Among nonhuman animals, dominance–subordination relationships are highly organized in troops of baboons, in which dominant males have more access to food resources and mates than do subordinate males and all males often appear to have dominance over females. In hyena groups, the relationship is reversed, with males subordinate to females.