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Human brain
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This article is about the human brain. For information about brains in general, see Brain.
Human brain
Skull and brain normal human.svg
Human brain and skull
Cerebral lobes.png
Cerebral lobes: the frontal lobe (pink), parietal lobe (green) and occipital lobe (blue)
Details
Precursor Neural tube
System Central nervous system
Neuroimmune system
Artery Internal carotid arteries, vertebral arteries
Vein Internal jugular vein, internal cerebral veins;
external veins: (superior, middle, and inferior cerebral veins), basal vein, and cerebellar veins
Identifiers
Latin Cerebrum[1]
Greek ἐγκέφαλος (enképhalos)[2]
MeSH D001921
TA A14.1.03.001
FMA 50801
Anatomical terminology
[edit on Wikidata]
The human brain is the central organ of the human nervous system, and with the spinal cord makes up the central nervous system. The brain consists of the cerebrum, the brainstem and the cerebellum. It controls most of the activities of the body, processing, integrating, and coordinating the information it receives from the sense organs, and making decisions as to the instructions sent to the rest of the body. The brain is contained in, and protected by, the skull bones of the head.
 
The cerebrum is the largest part of the human brain. It is divided into two cerebral hemispheres. The cerebral cortex is an outer layer of grey matter, covering the core of white matter. The cortex is split into the neocortex and the much smaller allocortex. The neocortex is made up of six neuronal layers, while the allocortex has three or four. Each hemisphere is conventionally divided into four lobes – the frontal, temporal, parietal, and occipital lobes. The frontal lobe is associated with executive functions including self-control, planning, reasoning, and abstract thought, while the occipital lobe is dedicated to vision. Within each lobe, cortical areas are associated with specific functions, such as the sensory, motor and association regions. Although the left and right hemispheres are broadly similar in shape and function, some functions are associated with one side, such as language in the left and visual-spatial ability in the right. The hemispheres are connected by commissural nerve tracts, the largest being the corpus callosum.
 
The cerebrum is connected by the brainstem to the spinal cord. The brainstem consists of the midbrain, the pons, and the medulla oblongata. The cerebellum is connected to the brainstem by pairs of tracts. Within the cerebrum is the ventricular system, consisting of four interconnected ventricles in which cerebrospinal fluid is produced and circulated. Underneath the cerebral cortex are several important structures, including the thalamus, the epithalamus, the pineal gland, the hypothalamus, the pituitary gland, and the subthalamus; the limbic structures, including the amygdala and the hippocampus; the claustrum, the various nuclei of the basal ganglia; the basal forebrain structures, and the three circumventricular organs. The cells of the brain include neurons and supportive glial cells. There are more than 86 billion neurons in the brain, and a more or less equal number of other cells. Brain activity is made possible by the interconnections of neurons and their release of neurotransmitters in response to nerve impulses. Neurons connect to form neural pathways, neural circuits, and elaborate network systems. The whole circuitry is driven by the process of neurotransmission.
 
The brain is protected by the skull, suspended in cerebrospinal fluid, and isolated from the bloodstream by the blood–brain barrier. However, the brain is still susceptible to damage, disease, and infection. Damage can be caused by trauma, or a loss of blood supply known as a stroke. The brain is susceptible to degenerative disorders, such as Parkinson's disease, dementias including Alzheimer's disease, and multiple sclerosis. Psychiatric conditions, including schizophrenia and clinical depression, are thought to be associated with brain dysfunctions. The brain can also be the site of tumours, both benign and malignant; these mostly originate from other sites in the body.
 
The study of the anatomy of the brain is neuroanatomy, while the study of its function is neuroscience. A number of techniques are used to study the brain. Specimens from other animals, which may be examined microscopically, have traditionally provided much information. Medical imaging technologies such as functional neuroimaging, and electroencephalography (EEG) recordings are important in studying the brain. The medical history of people with brain injury has provided insight into the function of each part of the brain. Brain research has evolved over time, with philosophical, experimental, and theoretical phases. The next phase has been predicted to be one of simulating brain activity.[3]
 
In culture, the philosophy of mind has for centuries attempted to address the question of the nature of consciousness and the mind-body problem. The pseudoscience of phrenology attempted to localise personality attributes to regions of the cortex in the 19th century. In science fiction, brain transplants are imagined in tales such as the 1942 Donovan's Brain.
 
 
Contents
1 Structure
1.1 Gross anatomy
1.2 Microanatomy
1.3 Cerebrospinal fluid
1.4 Blood supply
2 Development
3 Function
3.1 Motor control
3.2 Sensory
3.3 Regulation
3.4 Language
3.5 Lateralisation
3.6 Emotion
3.7 Cognition
4 Physiology
4.1 Neurotransmission
4.2 Metabolism
5 Research
5.1 Methods
5.2 Imaging
5.3 Gene and protein expression
6 Clinical significance
6.1 Injury
6.2 Disease
6.3 Tumours
6.4 Mental disorders
6.5 Epilepsy
6.6 Congenital
6.7 Stroke
6.8 Brain death
7 Society and culture
7.1 The mind
7.2 Brain size
7.3 In popular culture
8 History
8.1 Early history
8.2 Renaissance
8.3 Modern period
9 Comparative anatomy
10 See also
11 References
12 Bibliography
13 Notes
14 External links
Structure
 
Human brain (sagittal section)
See also: List of regions in the human brain and Outline of the human brain
Gross anatomy
Further information: Neuroscience of sex differences
The adult human brain weighs on average about 1.2–1.4 kg (2.6–3.1 lb) which is about 2% of the total body weight,[4][5] with a volume of around 1260 cm3 in men and 1130 cm3 in women.[6] There is substantial individual variation,[6] with the standard reference range for men being 1,180–1,620 g (2.60–3.57 lb)[7] and for women 1,030–1,400 g (2.27–3.09 lb).[8]
 
Neurological differences between the sexes have not been shown to correlate in any simple way with IQ or other measures of cognitive performance.[9]
 
The cerebrum, consisting of the cerebral hemispheres, forms the largest part of the brain and overlies the other brain structures.[10] The outer region of the hemispheres, the cerebral cortex, is grey matter, consisting of cortical layers of neurons. Each hemisphere is divided into four main lobes – the frontal lobe, parietal lobe, temporal lobe, and occipital lobe.[11] Three other lobes are included by some sources which are a central lobe, a limbic lobe, and an insular lobe.[12] The central lobe comprises the precentral gyrus and the postcentral gyrus and is included since it forms a distinct functional role.[12][13]
 
The brainstem, resembling a stalk, attaches to and leaves the cerebrum at the start of the midbrain area. The brainstem includes the midbrain, the pons, and the medulla oblongata. Behind the brainstem is the cerebellum (Latin: little brain).[10]
 
The cerebrum, brainstem, cerebellum, and spinal cord are covered by three membranes called meninges. T
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