出典(authority):フリー百科事典『ウィキペディア(Wikipedia)』「2015/05/23 18:33:06」(JST)
脳: 大脳 | |
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大脳
間脳
中脳
橋
延髄
脊髄
小脳
脳の矢状断。オレンジ色が大脳。
脳内での大脳の位置。赤色で示した部分が大脳。この大脳の表面を特に大脳皮質と言う(画像出典:Anatomography)
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名称 | |
日本語 | 大脳 |
英語 | Cerebrum |
関連構造 | |
上位構造 | 前脳 |
構成要素 | 大脳皮質、白質、大脳基底核 |
画像 | |
アナトモグラフィー | 三次元CG |
関連情報 | |
IBVD | 体積(面積) |
Brede Database | 階層関係、座標情報 |
NeuroNames | 関連情報一覧 |
NIF | 総合検索 |
MeSH | Cerebrum |
グレイの解剖学 | 書籍中の説明(英語) |
テンプレートを表示 |
大脳(だいのう、羅: 英: Cerebrum)、あるいは、終脳(英: Telencephalon)とは、中枢神経系の一部である。頭蓋骨の直下に位置し、ヒトでは非常に発達している。大きく分けると次の三つの構造に分けられる。
大脳の機能は次の通りである。 知覚、知覚情報の分析、統合、運動随意性統御、記憶、試行、神経の伝導路。
頭蓋内での大脳の位置を様々な角度から眺めた動画。赤色で示す部分が大脳。
ウィキメディア・コモンズには、大脳に関連するカテゴリがあります。 |
この項目は、医学に関連した書きかけの項目です。この項目を加筆・訂正などしてくださる協力者を求めています(プロジェクト:医学/Portal:医学と医療)。 |
この項目は、神経解剖学に関連した書きかけの項目です。この項目を加筆・訂正などしてくださる協力者を求めています(プロジェクト:医学/Portal:医学と医療)。 |
表・話・編・歴
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外側面 | 外側溝内部 と 極 | 内側面 |
前頭葉
頭頂葉
後頭葉
側頭葉
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島葉
前頭極
後頭極
側頭極
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側頭葉
後頭葉
頭頂葉
辺縁葉
前頭葉
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表・話・編・歴
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外側面 | 外側溝内部 | 内側面 - 上部 |
上前頭回
中前頭回
弁蓋部
+
三角部
+
眼窩部
ll
下前頭回
中心前回
中心後回
上頭頂小葉
下頭頂小葉
ll
縁上回
+
角回
後頭回
上側頭回
中側頭回
下側頭回
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島回
横側頭回
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舌状回
楔部
楔前部
中心傍小葉
帯状回 (前部+後部)
上前頭回
脳梁
梁下野
梁下回
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脳底部 - 眼窩面 | 脳底部 - 側頭葉下面 | 内側面 - 下部 |
眼窩回
直回
嗅球
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鉤
下側頭回
紡錘状回
海馬傍回
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歯状回
紡錘状回
鉤
海馬傍回
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Cerebrum | |
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Frontal lobe
Temporal lobe
Parietal lobe
Occipital
lobe The lobes of the cerebral cortex include the frontal (blue), temporal (green), occipital (red), and parietal (yellow) lobes . The cerebellum (unlabeled) is not part of the telencephalon.
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Diagram depicting the main subdivisions of the embryonic vertebrate brain.
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Details | |
Latin | Cerebrum |
Artery
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anterior cerebral, middle cerebral, posterior cerebral |
Vein
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cerebral veins |
Identifiers | |
Gray's | p.817 |
MeSH | A08.186.21.730.885 |
NeuroLex ID | Cerebrum |
TA | A14.1.03.008 A14.1.09.001 |
FMA | 62000 |
Anatomical terms of neuroanatomy |
The cerebrum (Latin for brain) refers to the parts of the brain containing the cerebral cortex (of the two cerebral hemispheres), as well as several subcortical structures, including the hippocampus, basal ganglia, and olfactory bulb. In humans, the cerebrum is the superior-most region of the central nervous system (CNS). The telencephalon refers to the embryonic structure from which the mature cerebrum develops. In mammals, the dorsal telencephalon, or pallium, develops into the cerebral cortex, and the ventral telencephalon, or subpallium, becomes the basal ganglia. The cerebrum is also divided into approximately symmetric left and right cerebral hemispheres.
With the assistance of the cerebellum, the cerebrum controls all voluntary actions in the body.
The cerebrum is the largest part of the brain. Depending upon the position of the animal it lies either in front or on top of the brainstem. In humans, the cerebrum is the largest and best-developed of the five major divisions of the brain. The cerebrum is the newest structure in the phylogenetic sense, and in mammals it is the largest and most developed, out of all known species.
The cerebrum is made up of the two cerebral hemispheres and their cortices, (the outer layers of gray matter), and the underlying regions of white matter.[1] Its subcortical structures include the hippocampus, basal ganglia and olfactory bulb.
The cerebral cortex, the outer layer of gray matter of the cerebrum, is found only in mammals. In larger mammals, including humans, the surface of the cerebral cortex folds to create gyri (ridges) and sulci (furrows) which increase the surface area.[2]
The cerebral cortex is generally classified into four lobes: the frontal, parietal, temporal, and occipital lobes. The lobes are classified based on their overlying neurocranial bones.[3]
The cerebrum is divided by the longitudinal fissure into two cerebral hemispheres, the right and the left. The right hemisphere controls and processes signals from the left side of the body, while the left hemisphere controls and processes signals from the right side of the body.[3] There is a strong but not complete bilateral symmetry between the hemispheres. The lateralization of brain function looks at the known and possible differences between the two.
In the developing vertebrate embryo, the neural tube is subdivided into four unseparated sections which then develop further into distinct regions of the CNS; these are the prosencephalon (forebrain), the mesencephalon (midbrain) the rhombencephalon (hindbrain) and the spinal cord.[4] The prosencephalon develops further into the telencephalon and the diencephalon. The dorsal telencephalon gives rise to the pallium (cerebral cortex in mammals and reptiles) and the ventral telencephalon generates the basal ganglia. The diencephalon develops into the thalamus and hypothalamus, including the optic vesicles (future retina).[5] The dorsal telencephalon then forms two lateral telencephalic vesicles, separated by the midline, which develop into the left and right cerebral hemispheres. Birds and fish have a dorsal telencephalon, like all vertebrates, but it is generally unlayered and therefore not considered a cerebral cortex. Only a layered cytoarchitecture can be considered a cortex.
Note: As the cerebrum is a gross division with many subdivisions and sub-regions, it is important to state that this section lists the functions that the cerebrum as a whole serves. See main articles on cerebral cortex and basal ganglia for more information. The cerebrum is a major part of the brain, controlling emotions, hearing, vision, personality and much more. It controls all voluntary actions.
The cerebrum directs the conscious or volitional motor functions of the body. These functions originate within the primary motor cortex and other frontal lobe motor areas where actions are planned. Upper motor neurons in the primary motor cortex send their axons to the brainstem and spinal cord to synapse on the lower motor neurons, which innervate the muscles. Damage to motor areas of cortex can lead to certain types of motor neuron disease. This kind of damage results in loss of muscular power and precision rather than total paralysis.
It functions as the center of sensory perception, memory, thoughts and judgement; the cerebrum also functions as the center of voluntary motor activity.
The primary sensory areas of the cerebral cortex receive and process visual, auditory, somatosensory, gustatory, and olfactory information. Together with association cortical areas, these brain regions synthesize sensory information into our perceptions of the world around us.
The olfactory bulb, responsible for the sense of smell, takes up a large area of the cerebrum in most vertebrates. However, in humans, this part of the brain is much smaller and lies underneath the frontal lobe. The olfactory sensory system is unique since the neurons in the olfactory bulb send their axons directly to the olfactory cortex, rather than to the thalamus first. Damage to the olfactory bulb results in a loss of olfaction (the sense of smell).
Speech and language are mainly attributed to the parts of the cerebral cortex. Motor portions of language are attributed to Broca's area within the frontal lobe. Speech comprehension is attributed to Wernicke's area, at the temporal-parietal lobe junction. These two regions are interconnected by a large white matter tract, the arcuate fasciculus. Damage to the Broca's area results in expressive aphasia (non-fluent aphasia) while damage to Wernicke's area results in receptive aphasia (also called fluent aphasia).
Explicit or declarative (factual) memory formation is attributed to the hippocampus and associated regions of the medial temporal lobe. This association was originally described after a patient known as HM had both his left and right hippocampus surgically removed to treat chronic temporal lobe epilepsy. After surgery, HM had anterograde amnesia, or the inability to form new memories.
Implicit or procedural memory, such as complex motor behaviors, involves the basal ganglia.
Short-term or working memory involves association areas of the cortex, especially the dorsolateral prefrontal cortex, as well as the hippocampus.
In the most primitive vertebrates, the hagfishes and lampreys, the cerebrum is a relatively simple structure receiving nerve impulses from the olfactory bulb. In cartilaginous and lobe-finned fishes and also in amphibians, a more complex structure is present, with the cerebrum being divided into three distinct regions. The lowermost (or ventral) region forms the basal nuclei, and contains fibres connecting the rest of the cerebrum to the thalamus. Above this, and forming the lateral part of the cerebrum, is the paleopallium, while the uppermost (or dorsal) part is referred to as the archipallium. The cerebrum remains largely devoted to olfactory sensation in these animals, in contrast to its much wider range of functions in amniotes.[6]
In ray-finned fishes the structure is somewhat different. The inner surfaces of the lateral and ventral regions of the cerebrum bulge up into the ventricles; these include both the basal nuclei and the various parts of the pallium and may be complex in structure, especially in teleosts. The dorsal surface of the cerebrum is membranous, and does not contain any nervous tissue.[6]
In the amniotes, the cerebrum becomes increasingly large and complex. In reptiles, the paleopallium is much larger than in amphibians and its growth has pushed the basal nuclei into the central regions of the cerebrum. As in the lower vertebrates, the grey matter is generally located beneath the white matter, but in some reptiles, it spreads out to the surface to form a primitive cortex, especially in the anterior part of the brain.[6]
In mammals, this development proceeds further, so that the cortex covers almost the whole of the cerebral hemispheres, especially in more developed species, such as the primates. The paleopallium is pushed to the ventral surface of the brain, where it becomes the olfactory lobes, while the archipallium becomes rolled over at the medial dorsal edge to form the hippocampus. In placental mammals, a corpus callosum also develops, further connecting the two hemispheres. The complex convolutions of the cerebral surface (see gyrus, gyrification) are also found only in higher mammals.[6] Although some large mammals (such as elephants) have particularly large cerebra, dolphins are the only species (other than humans) to have cerebra accounting for as much as 2 percent of their body weight.[7]
The cerebrum of birds are similarly enlarged to those of mammals, by comparison with reptiles. The increased size of bird brains was classically attributed to enlarged basal ganglia, with the other areas remaining primitive, but this view has been largely abandoned.[8] Birds appear to have undergone an alternate process of encephalization,[9] as they diverged from the other archosaurs, with few clear parallels to that experienced by mammals and their therapsid ancestors.
Cerebrum. Lateral face.Deep dissection.
Cerebrum. Medial face.Deep dissection.
Wikimedia Commons has media related to Cerebrum. |
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リンク元 | 「大脳」「cerebral」「cerebri」 |
拡張検索 | 「aqueduct of cerebrum」「deutocerebrum」 |
優位半球 | 劣位半球 | |
左 | 右 | |
側頭葉 | 感覚性失語、Wernicke失語、同名性上1/4半盲 | |
頭頂葉 | 対側の感覚 | |
ゲルストマン症候群(手指失認、左右識別障害、失算、失書) | 半側空間無視、病態失認、自己身体失認など | |
前頭葉 | 対側の運動麻痺、眼球運動(対側への追視)障害、運動性失語、知的及び精神的高次機能障害など | |
後頭葉 | 対側の同名半盲、両側後頭葉の障害ではアントン症候群 | |
小脳 | 筋共同運動障害、運動・平衡障害に関係し、運動失調を呈する。測定異常、反復拮抗運動障害、筋緊張低下、運動過多、歩行異常、異常姿勢、発語障害、眼振など |
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