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Artery Of Percheron
The artery of Percheron (AOP) is a rare anatomical variation in the brain vascularization in which a single arterial trunk arises from the posterior cerebral artery (PCA) to supply both sides of the thalamus and midbrain. Clinical significance The functions of the thalamus and midbrain include the regulation of consciousness, sleep and alertness. Occlusion of the artery of Percheron, for example by a clot, could result in a posterior circulation infarct Posterior circulation infarct (POCI) is a type of cerebral infarction affecting the posterior circulation supplying one side of the brain. Posterior circulation stroke syndrome (POCS) refers to the symptoms of a patient who clinically appears t ... impairing structures on both sides of the brain. This can produce a bizarre disturbance such as sleep from which the patient cannot be awakened. History The artery of Percheron was first described in 1973 by the French medical scientist Gerard Percheron. References Brain ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Posterior Cerebral Artery
The posterior cerebral artery (PCA) is one of a pair of cerebral arteries that supply oxygenated blood to the occipital lobe, part of the back of the human brain. The two arteries originate from the distal end of the basilar artery, where it bifurcates into the left and right posterior cerebral arteries. These anastomose with the middle cerebral arteries and internal carotid arteries via the posterior communicating arteries. Structure The posterior cerebral artery is subdivided into 4 sections P1: pre-communicating segment * Originated at the termination of the basilar artery * May give rise to the artery of Percheron if present P2: post-communicating segment * From the PCOM around the midbrain * Terminates as it enters the quadrigeminal ganglion * Gives rise to the choroidal branches (medial and lateral posterior choroidal arteries) P3: quadrigeminal segment * Courses posteromedially through the quadrigeminal cistern * Terminates as it enters the sulk of the occipital ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Posterior Cerebral Artery
The posterior cerebral artery (PCA) is one of a pair of cerebral arteries that supply oxygenated blood to the occipital lobe, part of the back of the human brain. The two arteries originate from the distal end of the basilar artery, where it bifurcates into the left and right posterior cerebral arteries. These anastomose with the middle cerebral arteries and internal carotid arteries via the posterior communicating arteries. Structure The posterior cerebral artery is subdivided into 4 sections P1: pre-communicating segment * Originated at the termination of the basilar artery * May give rise to the artery of Percheron if present P2: post-communicating segment * From the PCOM around the midbrain * Terminates as it enters the quadrigeminal ganglion * Gives rise to the choroidal branches (medial and lateral posterior choroidal arteries) P3: quadrigeminal segment * Courses posteromedially through the quadrigeminal cistern * Terminates as it enters the sulk of the occipital ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thalamus
The thalamus (from Greek θάλαμος, "chamber") is a large mass of gray matter located in the dorsal part of the diencephalon (a division of the forebrain). Nerve fibers project out of the thalamus to the cerebral cortex in all directions, allowing hub-like exchanges of information. It has several functions, such as the relaying of sensory signals, including motor signals to the cerebral cortex and the regulation of consciousness, sleep, and alertness. Anatomically, it is a paramedian symmetrical structure of two halves (left and right), within the vertebrate brain, situated between the cerebral cortex and the midbrain. It forms during embryonic development as the main product of the diencephalon, as first recognized by the Swiss embryologist and anatomist Wilhelm His Sr. in 1893. Anatomy The thalamus is a paired structure of gray matter located in the forebrain which is superior to the midbrain, near the center of the brain, with nerve fibers projecting out to the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Midbrain
The midbrain or mesencephalon is the forward-most portion of the brainstem and is associated with vision, hearing, motor control, sleep and wakefulness, arousal (alertness), and temperature regulation. The name comes from the Greek ''mesos'', "middle", and ''enkephalos'', "brain". Structure The principal regions of the midbrain are the tectum, the cerebral aqueduct, tegmentum, and the cerebral peduncles. Rostrally the midbrain adjoins the diencephalon (thalamus, hypothalamus, etc.), while caudally it adjoins the hindbrain (pons, medulla and cerebellum). In the rostral direction, the midbrain noticeably splays laterally. Sectioning of the midbrain is usually performed axially, at one of two levels – that of the superior colliculi, or that of the inferior colliculi. One common technique for remembering the structures of the midbrain involves visualizing these cross-sections (especially at the level of the superior colliculi) as the upside-down face of a be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anatomical Variation
An anatomical variation, anatomical variant, or anatomical variability is a presentation of body structure with morphological features different from those that are typically described in the majority of individuals. Anatomical variations are categorized into three types including morphometric (size or shape), consistency (present or absent), and spatial (proximal/distal or right/left). Variations are seen as normal in the sense that they are found consistently among different individuals, are mostly without symptoms, and are termed anatomical variations rather than abnormalities. Anatomical variations are mainly caused by genetics and may vary considerably between different populations. The rate of variation considerably differs between single organs, particularly in muscles. Knowledge of anatomical variations is important in order to distinguish them from pathological conditions. A very early paper published in 1898, presented anatomic variations to have a wide range and signi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brain
A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a vertebrate's body. In a human, the cerebral cortex contains approximately 14–16 billion neurons, and the estimated number of neurons in the cerebellum is 55–70 billion. Each neuron is connected by synapses to several thousand other neurons. These neurons typically communicate with one another by means of long fibers called axons, which carry trains of signal pulses called action potentials to distant parts of the brain or body targeting specific recipient cells. Physiologically, brains exert centralized control over a body's other organs. They act on the rest of the body both by generating patterns of muscle activity and by driving the secretion of chemicals called hormones. This centralized control allows rapid and coordinated respon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Consciousness
Consciousness, at its simplest, is sentience and awareness of internal and external existence. However, the lack of definitions has led to millennia of analyses, explanations and debates by philosophers, theologians, linguisticians, and scientists. Opinions differ about what exactly needs to be studied or even considered consciousness. In some explanations, it is synonymous with the mind, and at other times, an aspect of mind. In the past, it was one's "inner life", the world of introspection, of private thought, imagination and volition. Today, it often includes any kind of cognition, experience, feeling or perception. It may be awareness, awareness of awareness, or self-awareness either continuously changing or not. The disparate range of research, notions and speculations raises a curiosity about whether the right questions are being asked. Examples of the range of descriptions, definitions or explanations are: simple wakefulness, one's sense of selfhood or sou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sleep
Sleep is a sedentary state of mind and body. It is characterized by altered consciousness, relatively inhibited sensory activity, reduced muscle activity and reduced interactions with surroundings. It is distinguished from wakefulness by a decreased ability to react to stimuli, but more reactive than a coma or disorders of consciousness, with sleep displaying different, active brain patterns. Sleep occurs in repeating periods, in which the body alternates between two distinct modes: REM sleep and non-REM sleep. Although REM stands for "rapid eye movement", this mode of sleep has many other aspects, including virtual paralysis of the body. Dreams are a succession of images, ideas, emotions, and sensations that usually occur involuntarily in the mind during certain stages of sleep. During sleep, most of the body's systems are in an anabolic state, helping to restore the immune, nervous, skeletal, and muscular systems; these are vital processes that maintain mood, memory, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alertness
Alertness is the state of active attention by high sensory awareness such as being watchful and prompt to meet danger or emergency, or being quick to perceive and act. It is related for psychology . A lack of alertness is a symptom of a number of conditions, including narcolepsy, attention deficit disorder, chronic fatigue syndrome, depression, Addison's disease, or sleep deprivation. Pronounced lack of alertness can be graded as an altered level of consciousness. The word is formed from "alert", which comes from the Italian "all'erta" (on the watch, literally, on the height; 1618) Physiological aspects People who have to be alert during their jobs, such as air traffic controllers or pilots, often face challenges maintaining their alertness. Research shows that for people "...engaged in attention-intensive and monotonous tasks, retaining a constant level of alertness is rare if not impossible." If people employed in safety-related or transportation jobs have lapses in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vascular Occlusion
Vascular occlusion is a blockage of a blood vessel, usually with a clot. It differs from thrombosis in that it can be used to describe any form of blockage, not just one formed by a clot. When it occurs in a major vein, it can, in some cases, cause deep vein thrombosis. The condition is also relatively common in the retina, and can cause partial or total loss of vision. An occlusion can often be diagnosed using Doppler sonography (a form of ultrasound). Some medical procedures, such as embolisation, involve occluding a blood vessel to treat a particular condition. This can be to reduce pressure on aneurysms (weakened blood vessels) or to restrict a haemorrhage. It can also be used to reduce blood supply to tumours or growths in the body, and therefore restrict their development. Occlusion can be carried out using a ligature; by implanting small coils which stimulate the formation of clots; or, particularly in the case of cerebral aneurysms, by clipping. See also * Central ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clot
A thrombus (plural thrombi), colloquially called a blood clot, is the final product of the blood coagulation step in hemostasis. There are two components to a thrombus: aggregated platelets and red blood cells that form a plug, and a mesh of cross-linked fibrin protein. The substance making up a thrombus is sometimes called cruor. A thrombus is a healthy response to injury intended to stop and prevent further bleeding, but can be harmful in thrombosis, when a clot obstructs blood flow through healthy blood vessels in the circulatory system. In the microcirculation consisting of the very small and smallest blood vessels the capillaries, tiny thrombi known as microclots can obstruct the flow of blood in the capillaries. This can cause a number of problems particularly affecting the alveoli in the lungs of the respiratory system resulting from reduced oxygen supply. Microclots have been found to be a characteristic feature in severe cases of COVID-19, and in long COVID. Mural thr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Posterior Circulation Infarct
Posterior circulation infarct (POCI) is a type of cerebral infarction affecting the posterior circulation supplying one side of the brain. Posterior circulation stroke syndrome (POCS) refers to the symptoms of a patient who clinically appears to have had a posterior circulation infarct, but who has not yet had any diagnostic imaging (e.g. CT Scan) to confirm the diagnosis. It can cause the following symptoms: * Cranial nerve palsy AND contralateral motor/sensory defect * Bilateral motor or sensory defect * Eye movement problems (e.g.nystagmus) * Cerebellar dysfunction * Isolated homonymous hemianopia * Vertigo It has also been associated with deafness. See also * Stroke * Artery of Percheron The artery of Percheron (AOP) is a rare anatomical variation in the brain vascularization in which a single arterial trunk arises from the posterior cerebral artery (PCA) to supply both sides of the thalamus and midbrain. Clinical significance T ... References External links { ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
