This is an accepted version of this page
163-400: Headache , also known as cephalalgia , is the symptom of pain in the face , head , or neck . It can occur as a migraine , tension-type headache , or cluster headache . There is an increased risk of depression in those with severe headaches. Headaches can occur as a result of many conditions. There are a number of different classification systems for headaches. The most well-recognized
326-408: A central lobe , a limbic lobe , and an insular lobe . The central lobe comprises the precentral gyrus and the postcentral gyrus and is included since it forms a distinct functional role. 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
489-455: A cephalic flexure . This flexed part becomes the forebrain (prosencephalon); the adjoining curving part becomes the midbrain (mesencephalon) and the part caudal to the flexure becomes the hindbrain (rhombencephalon). These areas are formed as swellings known as the three primary brain vesicles . In the fifth week of development five secondary brain vesicles have formed. The forebrain separates into two vesicles – an anterior telencephalon and
652-486: A decreased appetite and decreased nutritional intake. A change in condition that deviates from baseline, such as moaning with movement or when manipulating a body part, and limited range of motion are also potential pain indicators. In patients who possess language but are incapable of expressing themselves effectively, such as those with dementia, an increase in confusion or display of aggressive behaviors or agitation may signal that discomfort exists, and further assessment
815-405: A nociceptor sends a message up the length of the nerve fibre to the nerve cells in the brain, signalling that a part of the body hurts. Primary headaches are more difficult to understand than secondary headaches. The exact mechanisms which cause migraines, tension headaches and cluster headaches are not known. There have been different hypotheses over time that attempt to explain what happens in
978-669: A CT scan should be done first. Headaches are most thoroughly classified by the International Headache Society 's International Classification of Headache Disorders (ICHD), which published the second edition in 2004. The third edition of the International Headache Classification was published in 2013 in a beta version ahead of the final version. This classification is accepted by the WHO . Other classification systems exist. One of
1141-646: A chronic headache that has changed character. For example, if a person has chronic weekly headaches with pressure on both sides of his head, and then develops a sudden severe throbbing headache on one side of his head, they have a new headache. It can be challenging to differentiate between low-risk, benign headaches and high-risk, dangerous headaches since symptoms are often similar. Headaches that are possibly dangerous require further lab tests and imaging to diagnose. The American College for Emergency Physicians published criteria for low-risk headaches. They are as follows: A number of characteristics make it more likely that
1304-409: A complex developmentally predetermined process which generates patterns of folds that are consistent between individuals and most species. The first groove to appear in the fourth month is the lateral cerebral fossa. The expanding caudal end of the hemisphere has to curve over in a forward direction to fit into the restricted space. This covers the fossa and turns it into a much deeper ridge known as
1467-488: A credible and convincing signal of the need for relief, help, and care. Idiopathic pain (pain that persists after the trauma or pathology has healed, or that arises without any apparent cause) may be an exception to the idea that pain is helpful to survival, although some psychodynamic psychologists argue that such pain is psychogenic, enlisted as a protective distraction to keep dangerous emotions unconscious. In pain science, thresholds are measured by gradually increasing
1630-431: A damaged body part while it heals, and to avoid similar experiences in the future. Most pain resolves once the noxious stimulus is removed and the body has healed, but it may persist despite removal of the stimulus and apparent healing of the body. Sometimes pain arises in the absence of any detectable stimulus, damage or disease. Pain is the most common reason for physician consultation in most developed countries. It
1793-410: A family history of migraines, women, and women who are experiencing hormonal changes or are taking birth control pills or are prescribed hormone replacement therapy . Tension headaches are thought to be caused by the activation of peripheral nerves in the head and neck muscles. Cluster headaches involve overactivation of the trigeminal nerve and hypothalamus in the brain, but the exact cause
SECTION 10
#17327971733371956-566: A headache depends on the underlying cause, but commonly involves pain medication (especially in case of migraine or cluster headaches). A headache is one of the most commonly experienced of all physical discomforts. About half of adults have a headache in a given year. Tension headaches are the most common, affecting about 1.6 billion people (21.8% of the population) followed by migraine headaches which affect about 848 million (11.7%). There are more than 200 types of headaches. Some are harmless and some are life-threatening . The description of
2119-525: A higher risk of being stigmatized, leading to less urgent treatment of women based on social expectations of their ability to accurately report it. This has been postulated to lead to extended emergency room wait times for women and frequent dismissal of their ability to accurately report pain. Pain is a symptom of many medical conditions. Knowing the time of onset, location, intensity, pattern of occurrence (continuous, intermittent, etc.), exacerbating and relieving factors, and quality (burning, sharp, etc.) of
2282-507: A lack of evidence base and scientific expertise. Cephalalgiaphobia is fear of headaches or getting a headache. New headaches are more likely to be dangerous secondary headaches . They can, however, simply be the first presentation of a chronic headache syndrome, like migraine or tension-type headaches. One recommended diagnostic approach is as follows. If any urgent red flags are present such as visual loss, new seizures, new weakness, new confusion, further workup with imaging and possibly
2445-514: A limited number of headaches. Pain Pain is a distressing feeling often caused by intense or damaging stimuli. The International Association for the Study of Pain defines pain as "an unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage." Pain motivates organisms to withdraw from damaging situations, to protect
2608-575: A lumbar puncture should be done (see red flags section for more details). If the headache is sudden onset (thunderclap headache), a computed tomography test to look for a brain bleed ( subarachnoid hemorrhage ) should be done. If the CT scan does not show a bleed, a lumbar puncture should be done to look for blood in the CSF, as the CT scan can be falsely negative and subarachnoid hemorrhages can be fatal. If there are signs of infection such as fever, rash, or stiff neck,
2771-409: A lumbar puncture to look for meningitis should be considered. If there is jaw claudication and scalp tenderness in an older person, a temporal artery biopsy to look for temporal arteritis should be performed and immediate treatment should be started. The US Headache Consortium has guidelines for neuroimaging of non-acute headaches. Most old, chronic headaches do not require neuroimaging. If a person has
2934-665: A mass or a bleed that is gradually growing, pressing on surrounding structures and causing worsening pain. People with neurological findings on exam, such as weakness, also need further workup. The American Headache Society recommends using "SSNOOP", a mnemonic to remember the red flags for identifying a secondary headache: Other red flag symptoms include: Old headaches are usually primary headaches and are not dangerous. They are most often caused by migraines or tension headaches . Migraines are often unilateral, pulsing headaches accompanied by nausea or vomiting. There may be an aura (visual symptoms, numbness or tingling) 30–60 minutes before
3097-419: A microscope . The cortex is divided into two main functional areas – a motor cortex and a sensory cortex . The primary motor cortex , which sends axons down to motor neurons in the brainstem and spinal cord, occupies the rear portion of the frontal lobe, directly in front of the somatosensory area. The primary sensory areas receive signals from the sensory nerves and tracts by way of relay nuclei in
3260-454: A non-communicative person, observation becomes critical, and specific behaviors can be monitored as pain indicators. Behaviors such as facial grimacing and guarding (trying to protect part of the body from being bumped or touched) indicate pain, as well as an increase or decrease in vocalizations, changes in routine behavior patterns and mental status changes. Patients experiencing pain may exhibit withdrawn social behavior and possibly experience
3423-806: A physiological point of view. Secondary headaches are caused by an underlying disease, like an infection , head injury , vascular disorders , brain bleed , stomach irritation, or tumors . Secondary headaches can be dangerous. Certain "red flags" or warning signs indicate a secondary headache may be dangerous. Ninety percent of all headaches are primary headaches. Primary headaches usually first start when people are between 20 and 40 years old. The most common types of primary headaches are migraines and tension-type headaches. They have different characteristics. Migraines typically present with pulsing head pain, nausea, photophobia (sensitivity to light) and phonophobia (sensitivity to sound). Tension-type headaches usually present with non-pulsing "bandlike" pressure on both sides of
SECTION 20
#17327971733373586-412: A posterior diencephalon . The telencephalon gives rise to the cerebral cortex, basal ganglia, and related structures. The diencephalon gives rise to the thalamus and hypothalamus. The hindbrain also splits into two areas – the metencephalon and the myelencephalon . The metencephalon gives rise to the cerebellum and pons. The myelencephalon gives rise to the medulla oblongata. Also during the fifth week,
3749-652: A primary problem with the nerves in the brain. Auras are thought to be caused by a wave of increased activity of neurons in the cerebral cortex (a part of the brain) known as cortical spreading depression followed by a period of depressed activity. Some people think headaches are caused by the activation of sensory nerves which release peptides or serotonin , causing inflammation in arteries, dura and meninges and also cause some vasodilation. Triptans , medications that treat migraines, block serotonin receptors and constrict blood vessels. People who are more susceptible to experiencing migraines without headaches are those who have
3912-556: A reduction in negative affect . Across studies, participants that were subjected to acute physical pain in the laboratory subsequently reported feeling better than those in non-painful control conditions, a finding which was also reflected in physiological parameters. A potential mechanism to explain this effect is provided by the opponent-process theory . Before the relatively recent discovery of neurons and their role in pain, various body functions were proposed to account for pain. There were several competing early theories of pain among
4075-707: A result of decreased sensation. A much smaller number of people are insensitive to pain due to an inborn abnormality of the nervous system, known as " congenital insensitivity to pain ". Children with this condition incur carelessly-repeated damage to their tongues, eyes, joints, skin, and muscles. Some die before adulthood, and others have a reduced life expectancy. Most people with congenital insensitivity to pain have one of five hereditary sensory and autonomic neuropathies (which includes familial dysautonomia and congenital insensitivity to pain with anhidrosis ). These conditions feature decreased sensitivity to pain together with other neurological abnormalities, particularly of
4238-415: A set of structures deep within the hemispheres involved in behaviour and movement regulation. The largest component is the striatum , others are the globus pallidus , the substantia nigra and the subthalamic nucleus . The striatum is divided into a ventral striatum, and dorsal striatum, subdivisions that are based upon function and connections. The ventral striatum consists of the nucleus accumbens and
4401-448: A state known as pain asymbolia, described as intense pain devoid of unpleasantness, with morphine injection or psychosurgery . Such patients report that they have pain but are not bothered by it; they recognize the sensation of pain but suffer little, or not at all. Indifference to pain can also rarely be present from birth; these people have normal nerves on medical investigations, and find pain unpleasant, but do not avoid repetition of
4564-443: A subtype of oligodendrocyte progenitor cells . Astrocytes are the largest of the glial cells. They are stellate cells with many processes radiating from their cell bodies . Some of these processes end as perivascular endfeet on capillary walls. The glia limitans of the cortex is made up of astrocyte endfeet processes that serve in part to contain the cells of the brain. Mast cells are white blood cells that interact in
4727-416: A thickened strip called the neural plate . By the fourth week of development the neural plate has widened to give a broad cephalic end, a less broad middle part and a narrow caudal end. These swellings are known as the primary brain vesicles and represent the beginnings of the forebrain (prosencephalon), midbrain (mesencephalon), and hindbrain (rhombencephalon). Neural crest cells (derived from
4890-432: Is "pain that extends beyond the expected period of healing". Chronic pain may be classified as " cancer-related " or "benign." Allodynia is pain experienced in response to a normally painless stimulus. It has no biological function and is classified by characteristics of the stimuli as cold, heat, touch, pressure or a pinprick. Phantom pain is pain felt in a part of the body that has been amputated , or from which
5053-488: Is 2 to 4 millimetres (0.079 to 0.157 in) thick, and deeply folded to give a convoluted appearance. Beneath the cortex is the cerebral white matter . The largest part of the cerebral cortex is the neocortex , which has six neuronal layers. The rest of the cortex is of allocortex , which has three or four layers. The cortex is mapped by divisions into about fifty different functional areas known as Brodmann's areas . These areas are distinctly different when seen under
Headache - Misplaced Pages Continue
5216-701: Is a common, reproducible tool in the assessment of pain and pain relief. The scale is a continuous line anchored by verbal descriptors, one for each extreme of pain where a higher score indicates greater pain intensity. It is usually 10 cm in length with no intermediate descriptors as to avoid marking of scores around a preferred numeric value. When applied as a pain descriptor, these anchors are often 'no pain' and 'worst imaginable pain". Cut-offs for pain classification have been recommended as no pain (0–4mm), mild pain (5–44mm), moderate pain (45–74mm) and severe pain (75–100mm). The Multidimensional Pain Inventory (MPI)
5379-647: Is a major symptom in many medical conditions, and can interfere with a person's quality of life and general functioning. People in pain experience impaired concentration, working memory , mental flexibility , problem solving and information processing speed, and are more likely to experience irritability, depression, and anxiety. Simple pain medications are useful in 20% to 70% of cases. Psychological factors such as social support , cognitive behavioral therapy , excitement, or distraction can affect pain's intensity or unpleasantness. First attested in English in 1297,
5542-496: Is a questionnaire designed to assess the psychosocial state of a person with chronic pain. Combining the MPI characterization of the person with their IASP five-category pain profile is recommended for deriving the most useful case description. Non-verbal people cannot use words to tell others that they are experiencing pain. However, they may be able to communicate through other means, such as blinking, pointing, or nodding. With
5705-475: Is also associated with increased depression, anxiety, fear, and anger. If I have matters right, the consequences of pain will include direct physical distress, unemployment, financial difficulties, marital disharmony, and difficulties in concentration and attention… Although pain is considered to be aversive and unpleasant and is therefore usually avoided, a meta-analysis which summarized and evaluated numerous studies from various psychological disciplines, found
5868-589: Is caused by stimulation of sensory nerve fibers that respond to stimuli approaching or exceeding harmful intensity ( nociceptors ), and may be classified according to the mode of noxious stimulation. The most common categories are "thermal" (e.g. heat or cold), "mechanical" (e.g. crushing, tearing, shearing, etc.) and "chemical" (e.g. iodine in a cut or chemicals released during inflammation ). Some nociceptors respond to more than one of these modalities and are consequently designated polymodal. Human brain The brain
6031-488: Is characterized by episodes of severe vomiting, and often occur alongside symptoms similar to those of migraine headaches (photophobia, abdominal pain, etc.). The brain itself is not sensitive to pain , because it lacks pain receptors . However, several areas of the head and neck do have pain receptors and can thus sense pain. These include the extracranial arteries, middle meningeal artery , large veins, venous sinuses , cranial and spinal nerves, head and neck muscles,
6194-579: Is controversial. Non-contrast computerized tomography (CT) scan is usually the first step in head imaging as it is readily available in Emergency Departments and hospitals and is cheaper than MRI. Non-contrast CT is best for identifying an acute head bleed. Magnetic Resonance Imaging (MRI) is best for brain tumors and problems in the posterior fossa , or back of the brain. MRI is more sensitive for identifying intracranial problems, however it can pick up brain abnormalities that are not relevant to
6357-547: Is distinctly located also activates the primary and secondary somatosensory cortex . Spinal cord fibers dedicated to carrying A-delta fiber pain signals and others that carry both A-delta and C fiber pain signals to the thalamus have been identified. Other spinal cord fibers, known as wide dynamic range neurons , respond to A-delta and C fibers and the much larger, more heavily myelinated A-beta fibers that carry touch, pressure, and vibration signals. Ronald Melzack and Patrick Wall introduced their gate control theory in
6520-664: 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
6683-474: Is essential for protection from injury, and recognition of the presence of injury. Episodic analgesia may occur under special circumstances, such as in the excitement of sport or war: a soldier on the battlefield may feel no pain for many hours from a traumatic amputation or other severe injury. Although unpleasantness is an essential part of the IASP definition of pain, it is possible in some patients to induce
Headache - Misplaced Pages Continue
6846-405: Is evident. Why the cortex wrinkles and folds is not well-understood, but gyrification has been linked to intelligence and neurological disorders , and a number of gyrification theories have been proposed. These theories include those based on mechanical buckling , axonal tension , and differential tangential expansion . What is clear is that gyrification is not a random process, but rather
7009-400: Is expressed in interneurons. Proteins expressed in glial cells include astrocyte markers GFAP and S100B whereas myelin basic protein and the transcription factor OLIG2 are expressed in oligodendrocytes. Cerebrospinal fluid is a clear, colourless transcellular fluid that circulates around the brain in the subarachnoid space , in the ventricular system , and in the central canal of
7172-401: Is generated by baroreceptors in aortic bodies in the aortic arch , and passed to the brain along the afferent fibres of the vagus nerve. Information about the pressure changes in the carotid sinus comes from carotid bodies located near the carotid artery and this is passed via a nerve joining with the glossopharyngeal nerve . This information travels up to the solitary nucleus in
7335-403: Is initially described as burning or tingling but may evolve into severe crushing or pinching pain, or the sensation of fire running down the legs or of a knife twisting in the flesh. Onset may be immediate or may not occur until years after the disabling injury. Surgical treatment rarely provides lasting relief. Breakthrough pain is transitory pain that comes on suddenly and is not alleviated by
7498-450: Is made up of six neuronal layers , while the allocortex has three or four. Each hemisphere is 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
7661-455: Is narrowly furrowed into numerous curved transverse fissures. Viewed from underneath between the two lobes is the third lobe the flocculonodular lobe. The cerebellum rests at the back of the cranial cavity , lying beneath the occipital lobes, and is separated from these by the cerebellar tentorium , a sheet of fibre. It is connected to the brainstem by three pairs of nerve tracts called cerebellar peduncles . The superior pair connects to
7824-507: Is necessary. Changes in behavior may be noticed by caregivers who are familiar with the person's normal behavior. Infants do feel pain , but lack the language needed to report it, and so communicate distress by crying. A non-verbal pain assessment should be conducted involving the parents, who will notice changes in the infant which may not be obvious to the health care provider. Pre-term babies are more sensitive to painful stimuli than those carried to full term. Another approach, when pain
7987-421: Is often described as shooting, crushing, burning or cramping. If the pain is continuous for a long period, parts of the intact body may become sensitized, so that touching them evokes pain in the phantom limb. Phantom limb pain may accompany urination or defecation . Local anesthetic injections into the nerves or sensitive areas of the stump may relieve pain for days, weeks, or sometimes permanently, despite
8150-404: Is passed to the olfactory cortex . Taste is generated from receptors on the tongue and passed along the facial and glossopharyngeal nerves into the solitary nucleus in the brainstem. Some taste information is also passed from the pharynx into this area via the vagus nerve . Information is then passed from here through the thalamus into the gustatory cortex . Autonomic functions of
8313-416: Is passed up a series of neurons through tracts in the spinal cord. The dorsal column–medial lemniscus pathway contains information about fine touch, vibration and position of joints. The pathway fibres travel up the back part of the spinal cord to the back part of the medulla, where they connect with second-order neurons that immediately send fibres across the midline . These fibres then travel upwards into
SECTION 50
#17327971733378476-412: Is suspected, is to give the person treatment for pain, and then watch to see whether the suspected indicators of pain subside. The way in which one experiences and responds to pain is related to sociocultural characteristics, such as gender, ethnicity, and age. An aging adult may not respond to pain in the same way that a younger person might. Their ability to recognize pain may be blunted by illness or
8639-459: Is that of the International Headache Society , which classifies it into more than 150 types of primary and secondary headaches. Causes of headaches may include dehydration ; fatigue ; sleep deprivation; stress ; the effects of medications (overuse) and recreational drugs, including withdrawal; viral infections; loud noises; head injury; rapid ingestion of a very cold food or beverage; and dental or sinus issues (such as sinusitis ). Treatment of
8802-437: Is the cerebellum ( Latin : little brain ). The cerebrum, brainstem, cerebellum, and spinal cord are covered by three membranes called meninges . The membranes are the tough dura mater ; the middle arachnoid mater and the more delicate inner pia mater . Between the arachnoid mater and the pia mater is the subarachnoid space and subarachnoid cisterns , which contain the cerebrospinal fluid . The outermost membrane of
8965-400: Is the central organ of the human nervous system , and with the spinal cord , comprises the central nervous system . It consists of the cerebrum , the brainstem and the cerebellum . The brain controls most of the activities of the body , processing, integrating, and coordinating the information it receives from the sensory nervous system . The brain integrates the instructions sent to
9128-425: Is unknown. Most headaches can be diagnosed by the clinical history alone. If the symptoms described by the person sound dangerous, further testing with neuroimaging or lumbar puncture may be necessary. Electroencephalography (EEG) is not useful for headache diagnosis. The first step to diagnosing a headache is to determine if the headache is old or new. A "new headache" can be a headache that has started recently, or
9291-527: The autonomic nervous system . A very rare syndrome with isolated congenital insensitivity to pain has been linked with mutations in the SCN9A gene, which codes for a sodium channel ( Na v 1.7 ) necessary in conducting pain nerve stimuli. Experimental subjects challenged by acute pain and patients in chronic pain experience impairments in attention control, working memory capacity , mental flexibility , problem solving, and information processing speed. Pain
9454-446: The blood–brain barrier . Pericytes play a major role in the formation of the tight junctions. The barrier is less permeable to larger molecules, but is still permeable to water, carbon dioxide, oxygen, and most fat-soluble substances (including anaesthetics and alcohol). The blood-brain barrier is not present in the circumventricular organs —which are structures in the brain that may need to respond to changes in body fluids—such as
9617-415: The cerebral hemispheres , forms the largest part of the brain and overlies the other brain structures. 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 . Three other lobes are included by some sources which are
9780-451: The common carotid arteries . They enter the cranium through the carotid canal , travel through the cavernous sinus and enter the subarachnoid space . They then enter the circle of Willis , with two branches, the anterior cerebral arteries emerging. These branches travel forward and then upward along the longitudinal fissure , and supply the front and midline parts of the brain. One or more small anterior communicating arteries join
9943-470: The extrapyramidal system . The sensory nervous system is involved with the reception and processing of sensory information . This information is received through the cranial nerves, through tracts in the spinal cord, and directly at centres of the brain exposed to the blood. The brain also receives and interprets information from the special senses of vision , smell , hearing , and taste . Mixed motor and sensory signals are also integrated. From
SECTION 60
#173279717333710106-443: The lateral sulcus and this marks out the temporal lobe. By the sixth month other sulci have formed that demarcate the frontal, parietal, and occipital lobes. A gene present in the human genome ( ARHGAP11B ) may play a major role in gyrification and encephalisation. The frontal lobe is involved in reasoning, motor control, emotion, and language. It contains the motor cortex , which is involved in planning and coordinating movement;
10269-405: The medial , paleospinothalamic tract . The neospinothalamic tract carries the fast, sharp A-delta signal to the ventral posterolateral nucleus of the thalamus . The paleospinothalamic tract carries the slow, dull C fiber pain signal. Some of the paleospinothalamic fibers peel off in the brain stem—connecting with the reticular formation or midbrain periaqueductal gray—and the remainder terminate in
10432-428: The medial geniculate nucleus , and finally the auditory radiation to the auditory cortex . The sense of smell is generated by receptor cells in the epithelium of the olfactory mucosa in the nasal cavity . This information passes via the olfactory nerve which goes into the skull through a relatively permeable part . This nerve transmits to the neural circuitry of the olfactory bulb from where information
10595-503: The meninges , falx cerebri , parts of the brainstem, eyes, ears, teeth, and lining of the mouth. Pial arteries, rather than pial veins are responsible for pain production. Headaches often result from traction or irritation of the meninges and blood vessels. The pain receptors may be stimulated by head trauma or tumours and cause headaches. Blood vessel spasms, dilated blood vessels , inflammation or infection of meninges and muscular tension can also stimulate pain receptors. Once stimulated,
10758-541: The neuroimmune system in the brain. Mast cells in the central nervous system are present in a number of structures including the meninges; they mediate neuroimmune responses in inflammatory conditions and help to maintain the blood–brain barrier, particularly in brain regions where the barrier is absent. Mast cells serve the same general functions in the body and central nervous system, such as effecting or regulating allergic responses, innate and adaptive immunity , autoimmunity , and inflammation . Mast cells serve as
10921-401: The olfactory tubercle whereas the dorsal striatum consists of the caudate nucleus and the putamen . The putamen and the globus pallidus lie separated from the lateral ventricles and thalamus by the internal capsule , whereas the caudate nucleus stretches around and abuts the lateral ventricles on their outer sides. At the deepest part of the lateral sulcus between the insular cortex and
11084-428: The pineal gland , area postrema , and some areas of the hypothalamus . There is a similar blood–cerebrospinal fluid barrier , which serves the same purpose as the blood–brain barrier, but facilitates the transport of different substances into the brain due to the distinct structural characteristics between the two barrier systems. At the beginning of the third week of development , the embryonic ectoderm forms
11247-419: The prefrontal cortex , which is responsible for higher-level cognitive functioning; and Broca’s area , which is essential for language production. The motor system of the brain is responsible for the generation and control of movement. Generated movements pass from the brain through nerves to motor neurons in the body, which control the action of muscles . The corticospinal tract carries movements from
11410-404: 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
11573-420: The spinal cord , with most connecting to interneurons , in turn connecting to lower motor neurons within the grey matter that then transmit the impulse to move to muscles themselves. The cerebellum and basal ganglia , play a role in fine, complex and coordinated muscle movements. Connections between the cortex and the basal ganglia control muscle tone, posture and movement initiation, and are referred to as
11736-463: The thalamus , the epithalamus , the pineal gland , the hypothalamus , the pituitary gland , and the subthalamus ; the limbic structures , including the amygdalae and the hippocampi , the claustrum , the various nuclei of the basal ganglia , the basal forebrain structures, and three circumventricular organs . Brain structures that are not on the midplane exist in pairs; for example, there are two hippocampi and two amygdalae. The cells of
11899-497: The thalamus . Primary sensory areas include the visual cortex of the occipital lobe , the auditory cortex in parts of the temporal lobe and insular cortex , and the somatosensory cortex in the parietal lobe . The remaining parts of the cortex are called the association areas . These areas receive input from the sensory areas and lower parts of the brain and are involved in the complex cognitive processes of perception , thought , and decision-making . The main functions of
12062-431: The ventricles where the cerebrospinal fluid is produced and circulated. Below the corpus callosum is the septum pellucidum , a membrane that separates the lateral ventricles . Beneath the lateral ventricles is the thalamus and to the front and below is the hypothalamus . The hypothalamus leads on to the pituitary gland . At the back of the thalamus is the brainstem. The basal ganglia , also called basal nuclei, are
12225-424: The ventrobasal complex in the thalamus where they connect with third-order neurons which send fibres up to the sensory cortex. The spinothalamic tract carries information about pain, temperature, and gross touch. The pathway fibres travel up the spinal cord and connect with second-order neurons in the reticular formation of the brainstem for pain and temperature, and also terminate at the ventrobasal complex of
12388-473: The 1965 Science article "Pain Mechanisms: A New Theory". The authors proposed that the thin C and A-delta (pain) and large diameter A-beta (touch, pressure, vibration) nerve fibers carry information from the site of injury to two destinations in the dorsal horn of the spinal cord, and that A-beta fiber signals acting on inhibitory cells in the dorsal horn can reduce the intensity of pain signals sent to
12551-447: The 19th-century development of specificity theory . Specificity theory saw pain as "a specific sensation, with its own sensory apparatus independent of touch and other senses". Another theory that came to prominence in the 18th and 19th centuries was intensive theory , which conceived of pain not as a unique sensory modality, but an emotional state produced by stronger than normal stimuli such as intense light, pressure or temperature. By
12714-415: The C fibers. These A-delta and C fibers enter the spinal cord via Lissauer's tract and connect with spinal cord nerve fibers in the central gelatinous substance of the spinal cord . These spinal cord fibers then cross the cord via the anterior white commissure and ascend in the spinothalamic tract . Before reaching the brain, the spinothalamic tract splits into the lateral , neospinothalamic tract and
12877-744: The ICHD-2 classification, the main types of secondary headaches include those that are due to head or neck trauma such as whiplash injury , intracranial hematoma , post craniotomy or other head or neck injury. Headaches caused by cranial or cervical vascular disorders such as ischemic stroke and transient ischemic attack , non-traumatic intracranial hemorrhage, vascular malformations or arteritis are also defined as secondary headaches. This type of headache may also be caused by cerebral venous thrombosis or different intracranial vascular disorders. Other secondary headaches are those due to intracranial disorders that are not vascular such as low or high pressure of
13040-436: The ICHD-2 includes a category that contains all the headaches that cannot be classified. Although the ICHD-2 is the most complete headache classification there is and it includes frequency in the diagnostic criteria of some types of headaches (primarily primary headaches), it does not specifically code frequency or severity which are left at the discretion of the examiner. The NIH classification consists of brief definitions of
13203-460: The POUND characteristics are present, a migraine is 24 times as likely a diagnosis than a tension-type headache ( likelihood ratio 24). If 3 characteristics of POUND are present, migraine is 3 times more likely a diagnosis than tension type headache ( likelihood ratio 3). If only 2 POUND characteristics are present, tension-type headaches are 60% more likely (likelihood ratio 0.41). Another study found
13366-429: The affective-motivational dimension. Thus, excitement in games or war appears to block both the sensory-discriminative and affective-motivational dimensions of pain, while suggestion and placebos may modulate only the affective-motivational dimension and leave the sensory-discriminative dimension relatively undisturbed. (p. 432) The paper ends with a call to action: "Pain can be treated not only by trying to cut down
13529-407: The ancient Greeks: Hippocrates believed that it was due to an imbalance in vital fluids . In the 11th century, Avicenna theorized that there were a number of feeling senses, including touch, pain, and titillation. In 1644, René Descartes theorized that pain was a disturbance that passed along nerve fibers until the disturbance reached the brain. The work of Descartes and Avicenna prefigured
13692-415: 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
13855-402: The brain divides into repeating segments called neuromeres . In the hindbrain these are known as rhombomeres . A characteristic of the brain is the cortical folding known as gyrification . For just over five months of prenatal development the cortex is smooth. By the gestational age of 24 weeks, the wrinkled morphology showing the fissures that begin to mark out the lobes of the brain
14018-433: The brain include the regulation, or rhythmic control of the heart rate and rate of breathing , and maintaining homeostasis . Blood pressure and heart rate are influenced by the vasomotor centre of the medulla, which causes arteries and veins to be somewhat constricted at rest. It does this by influencing the sympathetic and parasympathetic nervous systems via the vagus nerve . Information about blood pressure
14181-427: The brain is folded into ridges ( gyri ) and grooves ( sulci ), many of which are named, usually according to their position, such as the frontal gyrus of the frontal lobe or the central sulcus separating the central regions of the hemispheres. There are many small variations in the secondary and tertiary folds. The outer part of the cerebrum is the cerebral cortex , made up of grey matter arranged in layers. It
14344-471: The brain no longer receives signals. It is a type of neuropathic pain. The prevalence of phantom pain in upper limb amputees is nearly 82%, and in lower limb amputees is 54%. One study found that eight days after amputation, 72% of patients had phantom limb pain, and six months later, 67% reported it. Some amputees experience continuous pain that varies in intensity or quality; others experience several bouts of pain per day, or it may reoccur less often. It
14507-408: The brain to cause these headaches. Migraines are currently thought to be caused by dysfunction of the nerves in the brain. Previously, migraines were thought to be caused by a primary problem with the blood vessels in the brain. This vascular theory, which was developed in the 20th century by Wolff, suggested that the aura in migraines is caused by constriction of intracranial vessels (vessels inside
14670-489: The brain), and the headache itself is caused by rebound dilation of extracranial vessels (vessels just outside the brain). Dilation of these extracranial blood vessels activates the pain receptors in the surrounding nerves, causing a headache. The vascular theory is no longer accepted. Studies have shown migraine head pain is not accompanied by extracranial vasodilation, but rather only has some mild intracranial vasodilation. Currently, most specialists think migraines are due to
14833-486: The brain, through the spinal cord , to the torso and limbs. The cranial nerves carry movements related to the eyes, mouth and face. Gross movement – such as locomotion and the movement of arms and legs – is generated in the motor cortex , divided into three parts: the primary motor cortex , found in the precentral gyrus and has sections dedicated to the movement of different body parts. These movements are supported and regulated by two other areas, lying anterior to
14996-506: The brain. In 1968, Ronald Melzack and Kenneth Casey described chronic pain in terms of its three dimensions: They theorized that pain intensity (the sensory discriminative dimension) and unpleasantness (the affective-motivational dimension) are not simply determined by the magnitude of the painful stimulus, but "higher" cognitive activities can influence perceived intensity and unpleasantness. Cognitive activities may affect both sensory and affective experience, or they may modify primarily
15159-450: The brain. The medical history of people with brain injury has provided insight into the function of each part of the brain. Neuroscience research has expanded considerably, and research is ongoing. 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
15322-435: The brainstem. The brainstem also contains many cranial nerve nuclei and nuclei of peripheral nerves , as well as nuclei involved in the regulation of many essential processes including breathing , control of eye movements and balance. The reticular formation , a network of nuclei of ill-defined formation, is present within and along the length of the brainstem. Many nerve tracts , which transmit information to and from
15485-410: The cavernous sinus and superior and inferior petrosal sinuses. The sigmoid drains into the large internal jugular veins . The larger arteries throughout the brain supply blood to smaller capillaries . These smallest of blood vessels in the brain, are lined with cells joined by tight junctions and so fluids do not seep in or leak out to the same degree as they do in other capillaries; this creates
15648-464: The cerebral blood vessels. The pathway drains interstitial fluid from the tissue of the brain. The internal carotid arteries supply oxygenated blood to the front of the brain and the vertebral arteries supply blood to the back of the brain. These two circulations join in the circle of Willis , a ring of connected arteries that lies in the interpeduncular cistern between the midbrain and pons. The internal carotid arteries are branches of
15811-421: The cerebral cortex is the basement membrane of the pia mater called the glia limitans and is an important part of the blood–brain barrier . In 2023 a fourth meningeal membrane has been proposed known as the subarachnoid lymphatic-like membrane . The living brain is very soft, having a gel-like consistency similar to soft tofu. The cortical layers of neurons constitute much of the cerebral grey matter , while
15974-411: The cerebral cortex to the rest of the body, pass through the brainstem. The human brain is primarily composed of neurons , glial cells , neural stem cells , and blood vessels . Types of neuron include interneurons , pyramidal cells including Betz cells , motor neurons ( upper and lower motor neurons ), and cerebellar Purkinje cells . Betz cells are the largest cells (by size of cell body) in
16137-434: The cerebrospinal fluid pressure, non-infectious inflammatory disease, intracranial neoplasm, epileptic seizure or other types of disorders or diseases that are intracranial but that are not associated with the vasculature of the central nervous system . ICHD-2 classifies headaches that are caused by the ingestion of a certain substance or by its withdrawal as secondary headaches as well. This type of headache may result from
16300-404: The cerebrum and consists of the midbrain , pons and medulla . It lies in the back part of the skull , resting on the part of the base known as the clivus , and ends at the foramen magnum , a large opening in the occipital bone . The brainstem continues below this as the spinal cord , protected by the vertebral column . Ten of the twelve pairs of cranial nerves emerge directly from
16463-399: The characteristic symptoms of a migraine, neuroimaging is not needed as it is very unlikely the person has an intracranial abnormality. If the person has neurological findings, such as weakness, on exam, neuroimaging may be considered. All people who present with red flags indicating a dangerous secondary headache should receive neuroimaging. The best form of neuroimaging for these headaches
16626-540: The classification, ICHD-1, was published in 1988. The current revision, ICHD-2, was published in 2004. The classification uses numeric codes. The top, one-digit diagnostic level includes 14 headache groups. The first four of these are classified as primary headaches, groups 5-12 as secondary headaches, cranial neuralgia , central and primary facial pain and other headaches for the last two groups. The ICHD-2 classification defines migraines , tension-types headaches, cluster headache and other trigeminal autonomic headache as
16789-556: The cortex in the 19th century. In science fiction, brain transplants are imagined in tales such as the 1942 Donovan's Brain . 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, with a volume of around 1260 cm in men and 1130 cm in women. There is substantial individual variation, with the standard reference range for men being 1,180–1,620 g (2.60–3.57 lb) and for women 1,030–1,400 g (2.27–3.09 lb). The cerebrum , consisting of
16952-402: The crest and migrate in a craniocaudal (head to tail) wave inside the tube. Cells at the cephalic end give rise to the brain, and cells at the caudal end give rise to the spinal cord. The tube flexes as it grows, forming the crescent-shaped cerebral hemispheres at the head. The cerebral hemispheres first appear on day 32. Early in the fourth week, the cephalic part bends sharply forward in
17115-443: The deeper subcortical regions of myelinated axons , make up the white matter . The white matter of the brain makes up about half of the total brain volume. The cerebrum is the largest part of the brain and is divided into nearly symmetrical left and right hemispheres by a deep groove, the longitudinal fissure . Asymmetry between the lobes is noted as a petalia . The hemispheres are connected by five commissures that span
17278-413: The drug wearing off in a matter of hours; and small injections of hypertonic saline into the soft tissue between vertebrae produces local pain that radiates into the phantom limb for ten minutes or so and may be followed by hours, weeks, or even longer of partial or total relief from phantom pain. Vigorous vibration or electrical stimulation of the stump, or current from electrodes surgically implanted onto
17441-448: The dura mater and the covering of the skull. Blood from the cerebellum and midbrain drains into the great cerebral vein . Blood from the medulla and pons of the brainstem have a variable pattern of drainage, either into the spinal veins or into adjacent cerebral veins. The blood in the deep part of the brain drains, through a venous plexus into the cavernous sinus at the front, and the superior and inferior petrosal sinuses at
17604-401: The ectoderm) populate the lateral edges of the plate at the neural folds . In the fourth week—during the neurulation stage —the neural folds close to form the neural tube , bringing together the neural crest cells at the neural crest . The neural crest runs the length of the tube with cranial neural crest cells at the cephalic end and caudal neural crest cells at the tail. Cells detach from
17767-419: The fibres from the temporal halves of the opposite retinas to form the optic tracts . The arrangements of the eyes' optics and the visual pathways mean vision from the left visual field is received by the right half of each retina, is processed by the right visual cortex, and vice versa. The optic tract fibres reach the brain at the lateral geniculate nucleus , and travel through the optic radiation to reach
17930-400: The first published attempts was in 1951. The US National Institutes of Health developed a classification system in 1962. The International Classification of Headache Disorders (ICHD) is an in-depth hierarchical classification of headaches published by the International Headache Society . It contains explicit (operational) diagnostic criteria for headache disorders. The first version of
18093-553: The following factors independently each increase the chance of migraine over tension-type headache: nausea, photophobia, phonophobia, exacerbation by physical activity, unilateral, throbbing quality, chocolate as a headache trigger, and cheese as a headache trigger. Cluster headaches are relatively rare (1 in 1000 people) and are more common in men than women. They present with sudden onset explosive pain around one eye and are accompanied by autonomic symptoms (tearing, runny nose and red eye). Temporomandibular jaw pain (chronic pain in
18256-451: The following: Gastrointestinal disorders may cause headaches, including Helicobacter pylori infection, celiac disease , non-celiac gluten sensitivity , irritable bowel syndrome , inflammatory bowel disease , gastroparesis , and hepatobiliary disorders . The treatment of the gastrointestinal disorders may lead to a remission or improvement of headaches. Migraine headaches are also associated with Cyclic Vomiting Syndrome (CVS). CVS
18419-484: The frontal lobe are to control attention , abstract thinking, behaviour, problem-solving tasks, and physical reactions and personality. The occipital lobe is the smallest lobe; its main functions are visual reception, visual-spatial processing, movement, and colour recognition . There is a smaller occipital lobule in the lobe known as the cuneus . The temporal lobe controls auditory and visual memories , language , and some hearing and speech. The cerebrum contains
18582-510: The head, not accompanied by other symptoms. Such kind of headaches may be further classified into- episodic and chronic tension type headaches Other very rare types of primary headaches include: Headaches may be caused by problems elsewhere in the head or neck. Some of these are not harmful, such as cervicogenic headache (pain arising from the neck muscles). The excessive use of painkillers can paradoxically cause worsening painkiller headaches . More serious causes of secondary headaches include
18745-457: The headache and findings on neurological examination , determine whether additional tests are needed and what treatment is best. Headaches are broadly classified as "primary" or "secondary". Primary headaches are benign, recurrent headaches not caused by underlying disease or structural problems. For example, migraine is a type of primary headache. While primary headaches may cause significant daily pain and disability, they are not dangerous from
18908-419: The headache is due to potentially dangerous secondary causes which may be life-threatening or cause long-term damage. These "red flag" symptoms mean that a headache warrants further investigation with neuroimaging and lab tests. In general, people complaining of their "first" or "worst" headache warrant imaging and further workup. People with progressively worsening headache also warrant imaging, as they may have
19071-505: The headache, warning the person of a headache. Migraines may also not have auras. Tension-type headaches usually have bilateral "bandlike" pressure on both sides of the head usually without nausea or vomiting. However, some symptoms from both headache groups may overlap. It is important to distinguish between the two because the treatments are different. The mnemonic 'POUND' helps distinguish between migraines and tension-type headaches. POUND stands for: One review article found that if 4–5 of
19234-400: The intensity of a stimulus in a procedure called quantitative sensory testing which involves such stimuli as electric current , thermal (heat or cold), mechanical (pressure, touch, vibration), ischemic , or chemical stimuli applied to the subject to evoke a response. The " pain perception threshold " is the point at which the subject begins to feel pain, and the "pain threshold intensity" is
19397-430: The internal carotid arteries. Cerebral veins drain deoxygenated blood from the brain. The brain has two main networks of veins : an exterior or superficial network , on the surface of the cerebrum that has three branches, and an interior network . These two networks communicate via anastomosing (joining) veins. The veins of the brain drain into larger cavities of the dural venous sinuses usually situated between
19560-400: The intralaminar nuclei of the thalamus. Pain-related activity in the thalamus spreads to the insular cortex (thought to embody, among other things, the feeling that distinguishes pain from other homeostatic emotions such as itch and nausea) and anterior cingulate cortex (thought to embody, among other things, the affective/motivational element, the unpleasantness of pain), and pain that
19723-435: The jaw joint), and cervicogenic headache (headache caused by pain in muscles of the neck) are also possible diagnoses. For chronic, unexplained headaches, keeping a headache diary can be useful for tracking symptoms and identifying triggers, such as association with menstrual cycle, exercise and food. While mobile electronic diaries for smartphones are becoming increasingly common, a recent review found most are developed with
19886-447: The left and right subclavian arteries . They travel upward through transverse foramina which are spaces in the cervical vertebrae . Each side enters the cranial cavity through the foramen magnum along the corresponding side of the medulla. They give off one of the three cerebellar branches . The vertebral arteries join in front of the middle part of the medulla to form the larger basilar artery , which sends multiple branches to supply
20049-416: The likelihood of reporting pain. Patients may feel that certain treatments go against their religious beliefs. They may not report pain because they feel it is a sign that death is near. Many people fear the stigma of addiction, and avoid pain treatment so as not to be prescribed potentially addicting drugs. Many Asians do not want to lose respect in society by admitting they are in pain and need help, believing
20212-404: The longitudinal fissure, the largest of these is the corpus callosum . Each hemisphere is conventionally divided into four main lobes ; the frontal lobe , parietal lobe , temporal lobe , and occipital lobe , named according to the skull bones that overlie them. Each lobe is associated with one or two specialised functions though there is some functional overlap between them. The surface of
20375-399: The main effector cell through which pathogens can affect the biochemical signaling that takes place between the gastrointestinal tract and the central nervous system . Some 400 genes are shown to be brain-specific. In all neurons, ELAVL3 is expressed, and in pyramidal cells, NRGN and REEP2 are also expressed. GAD1 – essential for the biosynthesis of the neurotransmitter GABA –
20538-445: The main types of primary headaches. Also, according to the same classification, stabbing headaches and headaches due to cough , exertion and sexual activity ( sexual headache ) are classified as primary headaches. The daily-persistent headaches along with the hypnic headache and thunderclap headaches are considered primary headaches as well. Secondary headaches are classified based on their cause and not on their symptoms . According to
20701-435: The medulla and pons, and the two other anterior and superior cerebellar branches . Finally, the basilar artery divides into two posterior cerebral arteries . These travel outwards, around the superior cerebellar peduncles, and along the top of the cerebellar tentorium, where it sends branches to supply the temporal and occipital lobes. Each posterior cerebral artery sends a small posterior communicating artery to join with
20864-575: The mid-1890s, specificity was backed primarily by physiologists and physicians, and psychologists mostly backed the intensive theory . However, after a series of clinical observations by Henry Head and experiments by Max von Frey , the psychologists migrated to specificity almost en masse. By the century's end, most physiology and psychology textbooks presented pain specificity as fact. Some sensory fibers do not differentiate between noxious and non-noxious stimuli, while others (i.e., nociceptors ) respond only to noxious, high-intensity stimuli. At
21027-513: The midbrain; the middle pair connects to the medulla, and the inferior pair connects to the pons. The cerebellum consists of an inner medulla of white matter and an outer cortex of richly folded grey matter. The cerebellum's anterior and posterior lobes appear to play a role in the coordination and smoothing of complex motor movements, and the flocculonodular lobe in the maintenance of balance although debate exists as to its cognitive, behavioural and motor functions. The brainstem lies beneath
21190-447: The nervous system. The adult human brain is estimated to contain 86±8 billion neurons, with a roughly equal number (85±10 billion) of non-neuronal cells. Out of these neurons, 16 billion (19%) are located in the cerebral cortex, and 69 billion (80%) are in the cerebellum. Types of glial cell are astrocytes (including Bergmann glia ), oligodendrocytes , ependymal cells (including tanycytes ), radial glial cells , microglia , and
21353-480: The noxious stimulus is removed or the underlying damage or pathology has healed. But some painful conditions, such as rheumatoid arthritis , peripheral neuropathy , cancer , and idiopathic pain, may persist for years. Pain that lasts a long time is called " chronic " or "persistent", and pain that resolves quickly is called " acute ". Traditionally, the distinction between acute and chronic pain has relied upon an arbitrary interval of time between onset and resolution;
21516-403: The nucleus basalis, is considered to be the major cholinergic output of the central nervous system to the striatum and neocortex. The cerebellum is divided into an anterior lobe , a posterior lobe , and the flocculonodular lobe . The anterior and posterior lobes are connected in the middle by the vermis . Compared to the cerebral cortex, the cerebellum has a much thinner outer cortex that
21679-490: The overuse of some medications or exposure to some substances. HIV / AIDS , intracranial infections and systemic infections may also cause secondary headaches. The ICHD-2 system of classification includes the headaches associated with homeostasis disorders in the category of secondary headaches. This means that headaches caused by dialysis , high blood pressure , hypothyroidism , cephalalgia and even fasting are considered secondary headaches. Secondary headaches, according to
21842-400: The pain should be borne in silence, while other cultures feel they should report pain immediately to receive immediate relief. Gender can also be a perceived factor in reporting pain. Gender differences can be the result of social and cultural expectations, with, in some cultures, women expected to be more emotional and show pain, and men to be more stoic. As a result, female pain may be at
22005-487: The pain stimulus. Insensitivity to pain may also result from abnormalities in the nervous system . This is usually the result of acquired damage to the nerves, such as spinal cord injury , diabetes mellitus ( diabetic neuropathy ), or leprosy in countries where that disease is prevalent. These individuals are at risk of tissue damage and infection due to undiscovered injuries. People with diabetes-related nerve damage, for instance, sustain poorly-healing foot ulcers as
22168-400: The pain will help the examining physician to accurately diagnose the problem. For example, chest pain described as extreme heaviness may indicate myocardial infarction , while chest pain described as tearing may indicate aortic dissection . Functional magnetic resonance imaging brain scanning has been used to measure pain, and correlates well with self-reported pain. Nociceptive pain
22331-497: The patient's regular pain management . It is common in cancer patients who often have background pain that is generally well-controlled by medications, but who also sometimes experience bouts of severe pain that from time to time "breaks through" the medication. The characteristics of breakthrough cancer pain vary from person to person and according to the cause. Management of breakthrough pain can entail intensive use of opioids , including fentanyl . The ability to experience pain
22494-512: The peripheral end of the nociceptor, noxious stimuli generate currents that, above a given threshold, send signals along the nerve fiber to the spinal cord. The "specificity" (whether it responds to thermal, chemical, or mechanical features of its environment) of a nociceptor is determined by which ion channels it expresses at its peripheral end. So far, dozens of types of nociceptor ion channels have been identified, and their exact functions are still being determined. The pain signal travels from
22657-491: The periphery to the spinal cord along A-delta and C fibers. Because the A-delta fiber is thicker than the C fiber, and is thinly sheathed in an electrically insulating material ( myelin ), it carries its signal faster (5–30 m/s ) than the unmyelinated C fiber (0.5–2 m/s). Pain evoked by the A-delta fibers is described as sharp and is felt first. This is followed by a duller pain—often described as burning—carried by
22820-609: The person's headaches. The American College of Radiology recommends the following imaging tests for different specific situations: A lumbar puncture is a procedure in which cerebral spinal fluid is removed from the spine with a needle. A lumbar puncture is necessary to look for infection or blood in the spinal fluid. A lumbar puncture can also evaluate the pressure in the spinal column, which can be useful for people with idiopathic intracranial hypertension (usually young, obese women who have increased intracranial pressure), or other causes of increased intracranial pressure. In most cases,
22983-435: The primary motor cortex: the premotor area and the supplementary motor area . The hands and mouth have a much larger area dedicated to them than other body parts, allowing finer movement; this has been visualised in a motor homunculus . Impulses generated from the motor cortex travel along the corticospinal tract along the front of the medulla and cross over ( decussate ) at the medullary pyramids . These then travel down
23146-474: The question of why pain should have the quality of being painful. He describes the alternative as a mental raising of a "red flag". To argue why that red flag might be insufficient, Dawkins argues that drives must compete with one another within living beings. The most "fit" creature would be the one whose pains are well balanced. Those pains which mean certain death when ignored will become the most powerfully felt. The relative intensities of pain, then, may resemble
23309-537: The relative importance of that risk to our ancestors. This resemblance will not be perfect, however, because natural selection can be a poor designer . This may have maladaptive results such as supernormal stimuli . Pain, however, does not only wave a "red flag" within living beings but may also act as a warning sign and a call for help to other living beings. Especially in humans who readily helped each other in case of sickness or injury throughout their evolutionary history, pain might be shaped by natural selection to be
23472-411: The rest of the body. The brain is contained in, and protected by, the skull of the head . The cerebrum, the largest part of the human brain, consists of two cerebral hemispheres . Each hemisphere has an inner core composed of white matter , and an outer surface – the cerebral cortex – composed of grey matter . The cortex has an outer layer, the neocortex , and an inner allocortex . The neocortex
23635-521: The same classification system, can also be due to the injury of any of the facial structures including teeth , jaws, or temporomandibular joint . Headaches caused by psychiatric disorders such as somatization or psychotic disorders are also classified as secondary headaches. The ICHD-2 classification puts cranial neuralgias and other types of neuralgia in a different category. According to this system, there are 19 types of neuralgias and headaches due to different central causes of facial pain. Moreover,
23798-654: The sensory input by anesthetic block, surgical intervention and the like, but also by influencing the motivational-affective and cognitive factors as well." (p. 435) Pain is part of the body's defense system, producing a reflexive retraction from the painful stimulus, and tendencies to protect the affected body part while it heals, and avoid that harmful situation in the future. It is an important part of animal life, vital to healthy survival. People with congenital insensitivity to pain have reduced life expectancy . In The Greatest Show on Earth: The Evidence for Evolution , biologist Richard Dawkins addresses
23961-416: The sides, and the inferior sagittal sinus at the back. Blood drains from the outer brain into the large superior sagittal sinus , which rests in the midline on top of the brain. Blood from here joins with blood from the straight sinus at the confluence of sinuses . Blood from here drains into the left and right transverse sinuses . These then drain into the sigmoid sinuses , which receive blood from
24124-524: 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 . Numerous 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
24287-419: The skin, the brain receives information about fine touch , pressure , pain , vibration and temperature . From the joints, the brain receives information about joint position . The sensory cortex is found just near the motor cortex, and, like the motor cortex, has areas related to sensation from different body parts. Sensation collected by a sensory receptor on the skin is changed to a nerve signal, that
24450-535: The spinal cord, all produce relief in some patients. Mirror box therapy produces the illusion of movement and touch in a phantom limb which in turn may cause a reduction in pain. Paraplegia , the loss of sensation and voluntary motor control after serious spinal cord damage, may be accompanied by girdle pain at the level of the spinal cord damage, visceral pain evoked by a filling bladder or bowel, or, in five to ten percent of paraplegics, phantom body pain in areas of complete sensory loss. This phantom body pain
24613-416: The spinal cord. It also fills some gaps in the subarachnoid space, known as subarachnoid cisterns . The four ventricles, two lateral , a third , and a fourth ventricle , all contain a choroid plexus that produces cerebrospinal fluid. The third ventricle lies in the midline and is connected to the lateral ventricles. A single duct , the cerebral aqueduct between the pons and the cerebellum, connects
24776-431: The spinal cord. The brainstem consists of the midbrain , the pons , and the medulla oblongata . The cerebellum is connected to the brainstem by three pairs of nerve tracts called cerebellar peduncles . 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 structures, including
24939-408: The stimulus intensity at which the stimulus begins to hurt. The " pain tolerance threshold" is reached when the subject acts to stop the pain. A person's self-report is the most reliable measure of pain. Some health care professionals may underestimate pain severity. A definition of pain widely employed in nursing, emphasizing its subjective nature and the importance of believing patient reports,
25102-441: The striatum is a thin neuronal sheet called the claustrum . Below and in front of the striatum are a number of basal forebrain structures. These include the nucleus basalis , diagonal band of Broca , substantia innominata , and the medial septal nucleus . These structures are important in producing the neurotransmitter , acetylcholine , which is then distributed widely throughout the brain. The basal forebrain, in particular
25265-405: The subarachnoid space. It is constantly being regenerated and absorbed, and is replaced about once every 5–6 hours. A glymphatic system has been described as the lymphatic drainage system of the brain. The brain-wide glymphatic pathway includes drainage routes from the cerebrospinal fluid, and from the meningeal lymphatic vessels that are associated with the dural sinuses , and run alongside
25428-415: The thalamus for gross touch. Vision is generated by light that hits the retina of the eye. Photoreceptors in the retina transduce the sensory stimulus of light into an electrical nerve signal that is sent to the visual cortex in the occipital lobe. Visual signals leave the retinas through the optic nerves . Optic nerve fibres from the retinas' nasal halves cross to the opposite sides joining
25591-441: The third ventricle to the fourth ventricle. Three separate openings, the middle and two lateral apertures , drain the cerebrospinal fluid from the fourth ventricle to the cisterna magna , one of the major cisterns. From here, cerebrospinal fluid circulates around the brain and spinal cord in the subarachnoid space, between the arachnoid mater and pia mater. At any one time, there is about 150mL of cerebrospinal fluid – most within
25754-405: The two anterior cerebral arteries shortly after they emerge as branches. The internal carotid arteries continue forward as the middle cerebral arteries . They travel sideways along the sphenoid bone of the eye socket , then upwards through the insula cortex , where final branches arise. The middle cerebral arteries send branches along their length. The vertebral arteries emerge as branches of
25917-460: The two most commonly used markers being 3 months and 6 months since the onset of pain, though some theorists and researchers have placed the transition from acute to chronic pain at 12 months. Others apply "acute" to pain that lasts less than 30 days, "chronic" to pain of more than six months' duration, and "subacute" to pain that lasts from one to six months. A popular alternative definition of "chronic pain", involving no arbitrarily fixed duration,
26080-410: The use of medication . Depression may also keep older adult from reporting they are in pain. Decline in self-care may also indicate the older adult is experiencing pain. They may be reluctant to report pain because they do not want to be perceived as weak, or may feel it is impolite or shameful to complain, or they may feel the pain is a form of deserved punishment. Cultural barriers may also affect
26243-420: The visual cortex. Hearing and balance are both generated in the inner ear . Sound results in vibrations of the ossicles which continue finally to the hearing organ , and change in balance results in movement of liquids within the inner ear . This creates a nerve signal that passes through the vestibulocochlear nerve . From here, it passes through to the cochlear nuclei , the superior olivary nucleus ,
26406-554: The word peyn comes from the Old French peine , in turn from Latin poena meaning "punishment, penalty" (also meaning "torment, hardship, suffering" in Late Latin) and that from Greek ποινή ( poine ), generally meaning "price paid, penalty, punishment". The International Association for the Study of Pain recommends using specific features to describe a patient's pain: Pain is usually transitory, lasting only until
26569-553: Was introduced by Margo McCaffery in 1968: "Pain is whatever the experiencing person says it is, existing whenever he says it does". To assess intensity, the patient may be asked to locate their pain on a scale of 0 to 10, with 0 being no pain at all, and 10 the worst pain they have ever felt. Quality can be established by having the patient complete the McGill Pain Questionnaire indicating which words best describe their pain. The visual analogue scale
#336663