Glossary
Note to the learner
This glossary contains neuronatomical terms, as well as terms commonly used clinically to describe neurological symptoms and physical findings of a neurological examination; few clinical syndromes are included.
Abadie’s Sign — Abadie’s sign is the absence or diminution of pain sensation when exerting deep pressure on the Achilles tendon by squeezing. This is a frequent finding in the tabes dorsalis variant of neurosyphilis (i.e., with dorsal column disease).
Cross References — Argyll Robertson pupil
Abdominal Paradox — see PARADOXICAL BREATHING
Abdominal Reflexes — Both superficial and deep abdominal reflexes are described, of which the superficial (cutaneous) reflexes are the more commonly tested in clinical practice. A wooden stick or pin is used to scratch the abdomi- nal wall, from the flank to the midline, parallel to the line of the der- matomal strips, in upper (supraumbilical), middle (umbilical), and lower (infraumbilical) areas. The maneuver is best performed at the end of expiration when the abdominal muscles are relaxed, since the reflexes may be lost with muscle tensing; to avoid this, patients should lie supine with their arms by their sides.
Superficial abdominal reflexes are lost in a number of circum- stances:
- normal old age obesity
- after abdominal surgeryafter
- multiple pregnancies
- in acute abdominal disorders (Rosenbach’s sign).
However, absence of all superficial abdominal reflexes may be of localizing value for corticospinal pathway damage (upper motor neu- rone lesions) above T6. Lesions at or below T10 lead to selective loss of the lower reflexes with the upper and middle reflexes intact, in which case Beevor’s sign may also be present. All abdominal reflexes are preserved with lesions below T12.
Abdominal reflexes are said to be lost early in multiple sclerosis, but late in motor neurone disease, an observation of possible clinical use, particularly when differentiating the primary lateral sclerosis vari- ant of motor neurone disease from multiple sclerosis. However, no prospective study of abdominal reflexes in multiple sclerosis has been reported.
Cross References — Beevor’s sign; Upper motor neurone (UMN) syndrome
Abducens nerve — 6th cranial nerve (CN VI); to lateral rectus muscle for abduction of the eye
Abducens (VI) Nerve Palsy — Abducens (VI) nerve palsy causes a selective weakness of the lateral rectus muscle resulting in impaired abduction of the eye, manifest clin- ically as diplopia on lateral gaze, or on shifting gaze from a near to a distant object.
Abducens (VI) nerve palsy may be due to:
- Microinfarction in the nerve, due to hypertension, diabetes mellitus
- Raised intracranial pressure: a “false-localizing sign,” possibly caused by stretching of the nerve in its long intracranial course
over the ridge of the petrous temporal bone - Nuclear pontine lesions: congenital (e.g., Duane retraction syn- drome, Möbius syndrome).
Isolated weakness of the lateral rectus muscle may also occur in myasthenia gravis. In order not to overlook this fact, and miss a poten- tially treatable condition, it is probably better to label isolated abduc- tion failure as “lateral rectus palsy,” rather than abducens nerve palsy, until the etiological diagnosis is established.
Excessive or sustained convergence associated with a midbrain lesion (diencephalic-mesencephalic junction) may also result in slow or restricted abduction (pseudo-abducens palsy, “midbrain pseudo- sixth”).
Cross References — Diplopia; “False-localizing signs”
Absence — An absence, or absence attack, is a brief interruption of awareness of epileptic origin. This may be a barely noticeable suspension of speech or attentiveness, without postictal confusion or awareness that an attack has occurred, as in idiopathic generalized epilepsy of absence type (absence epilepsy; petit mal), a disorder exclusive to childhood and associated with 3 Hz spike and slow wave EEG abnormalities.
Absence epilepsy may be confused with a more obvious distanc- ing, “trance-like” state, or “glazing over,” possibly with associated automatisms, such as lip smacking, due to a complex partial seizure of temporal lobe origin (“atypical absence”).
Ethosuximide and/or sodium valproate are the treatments of choice for idiopathic generalized absence epilepsy, whereas carba- mazepine, sodium valproate, or lamotrigine are first-line agents for localization-related complex partial seizures.
Cross References — Automatism; Seizures
Abulia — Abulia (aboulia) is a “syndrome of hypofunction,” characterized by lack of initiative, spontaneity and drive (aspontaneity), apathy, slowness of thought (bradyphrenia), and blunting of emotional responses and response to external stimuli. It may be confused with the psychomotor retardation of depression and is sometimes labeled as “pseudodepres- sion.” More plausibly, abulia has been thought of as a minor or partial form of akinetic mutism. There may also be some clinical overlap with catatonia. Abulia may result from frontal lobe damage, most particularly that involving the frontal convexity, and has also been reported with focal lesions of the caudate nucleus, thalamus, and midbrain. As with akinetic mutism, it is likely that lesions anywhere in the “centromedial core” of the brain, from frontal lobes to brainstem, may produce this picture.
Pathologically, abulia may be observed in:
- Infarcts in anterior cerebral artery territory and ruptured anterior communicating artery aneurysms, causing basal forebrain dam- age.
- Closed head injury
- Parkinson’s disease; sometimes as a forerunner of a frontal lobe dementia
- Other causes of frontal lobe disease: tumor, abscess
- Metabolic, electrolyte disorders: hypoxia, hypoglycemia, hepatic encephalopathy
Treatment is of the underlying cause where possible. There is anec- dotal evidence that the dopamine agonist bromocriptine may help.
Cross References — Akinetic mutism; Apathy; Bradyphrenia; Catatonia; Frontal lobe syndromes; Psychomotor retardation
Acalculia —
Accessory nerve — 11th cranial nerve (CN XI) — see spinal accessory nerve
Afferent — conduction toward the central nervous system; usually means sensory
Agnosia — loss of ability to recognize the significance of sensory stimuli (tactile, auditory, visual), even though the primary sensory systems are intact
Agonist — a muscle that performs a certain movement of the joint; the opposing muscle is called the antagonist
Agraphia — inability to write due to a lesion of higher brain centers, even though muscle strength and coordination are preserved
Akinesia — absence or loss of motor function; lack of spontaneous movement; difficulty in initiating movement (as in Parkinson's disease)
Alexia — loss of ability to grasp the meaning of written words; inability to read due to a central lesion; word blindness
Allocortex — the phylogenetically older cerebral cortex, consisting of less than six layers; includes paleocortex (e.g., subicular region = three to five layers) and archicortex (e.g., hippocampus proper and dentate = three layers)
Alpha motor neuron — another name for the anterior (ventral) horn cell, also called the lower motor neuron
Ammon's horn — the hippocampus proper, which has an outline in cross-section suggestive of a ram's horn; also called the Cornu Ammonis (CA)
Amygdala — amygdaloid nucleus or body in the temporal lobe of the cerebral hemisphere; a nucleus of the limbic system
Angiogram — display of blood vessels for diagnostic purposes, using, x-rays, MRI or CT, usually by using contrast medium injected into the vascular system
Anopia — a defect in the visual field (e.g., hemianopia — loss of one-half of visual field; quadrantanopia — loss of one-quarter of visual field)
Antagonist — a muscle that opposes or resists the action of another muscle, which is called the agonist
Antidromic — relating to the propagation of an impulse along an axon in a direction that is the reverse of the normal or usual direction
Aphasia — an acquired disruption or disorder of language, specifically a deficit of expression using speech or of comprehending spoken or written language; global aphasia is a severe form affecting all language areas
Apopotosis — programmed cell death, either genetically determined or following an insult or injury to the cell
Apraxia — loss of ability to carry out purposeful or skilled movements despite the preservation of power, sensation, and coordination
Arachnoid — the middle meningeal layer, forming the outer boundary of the subarachnoid space
Areflexia — loss of reflex as tested using the myotatic, stretch, deep tendon reflex
Archicerebellum — a phylogenetically old part of the cerebellum, functioning in the maintenance of equilibrium; anatomically, the flocculonodular lobe
Archicortex — three-layered cortex included in the limbic system; located mainly in the hippocampus proper and dentate gyrus of the temporal lobe
Area postrema — an area involved in vomiting; located in the caudal part of the floor of the fourth ventricle, with no blood-brain-barrier
Ascending tract — central sensory pathway, e.g., from spinal cord to brainstem, cerebellum, or thalamus
Association fibers — fibers connecting parts of the cerebral hemisphere, on the same side
Astereognosis — loss of ability to recognize the nature of objects or to appreciate their shape by touching or feeling them
Astrocyte — a type of neuroglial cell with metabolic and structural functions; reacts to injury of the CNS by forming a gliotic "scar"
Asynergy — impairment of the proper sequencing in the contraction of muscles, at the proper moment, and of theproper degree, so that an action is not executed smoothly or accurately
Ataxia — a loss of coordination of voluntary movements; often associated with cerebellar dysfunction
Athetosis — slow writhing movements of the limbs, especially of the hands, not under voluntary control, caused by degenerative changes in the striatum
Autonomic — autonomic nervous system; usually taken to mean the efferent or motor innervation of viscera (smooth muscle and glands)
Autonomic nervous system (ANS) — visceral innervation; sympathetic and parasympathetic divisions system
Axon — efferent process of a neuron, conducting impulses to other neurons or to muscle fibers (striated and smooth) and gland cells
Analgesia — pain relief (see Blockade)
Babinski response — Babinski reflex is not correct; stroking the outer border of the sole of the foot in an adult normally results in a plantar (downgoing) of the toes; the Babinski response consists of an upgoing of the first toe and a fanning of the other toes, indicating a lesion of the pyramidal (cortico-spinal) tract
Basal ganglia (nuclei) — CNS nuclei involved in motor control, the caudate, putamen and globus pallidus (the lentiform nucleus); including, functionally, the subthalamus and the substantia nigra
Basilar artery — the major artery supplying the brainstem and cerebellum, formed by the two vertebral arteries
Brachium — a large bundle of fibers connecting one part with another (e.g., brachium associated with the inferior and superior colliculi of the midbrain)
Bradykinesia — abnormally slow initiation of voluntary movements (usually seen in Parkinson's disease)
Brainstem — includes the medulla, pons, and midbrain
Brodmann areas — numerical subdivisions of the cerebral cortex on the basis of histological differences between different functional areas (e.g. area 4 = motor cortex; area 17 = primary visual area)
Bulb — referred at one time to the medulla but in the context of "cortico-bulbar tract" refers to the whole brainstem in which the motor nuclei of cranial nerves and other nuclei are located
Carotid siphon — hairpin bend of the internal carotid artery within the skull
CAT or CT scan — computerized (Axial) Tomography; a diagnostic imaging technique that uses x-rays and computer reconstruction of the brain
Cauda equina — "horse's tail"; the lower lumbar, sacral, and coccygeal spinal nerve roots within the subarachnoid space of the lumbar (CSF) cistern
Caudal — toward the tail, or hindmost part of neuraxis
Caudate nucleus — part of the neostriatum, consists of a head, body, and tail (which extends into the temporal lobe)
Central nervous system (CNS) — brain (cerebral hemispheres), including diencephalon, cerebellum, brainstem, and spinal cord
Cerebellar peduncles — inferior, middle, and superior; fiber tracts linking the cerebellum and brainstem
Cerebellum — the little brain; an older part of the brain with motor functions, dorsal to the brainstem, situated in the posterior cranial fossa
Cerebral aqueduct (of Sylvius) — aqueduct of the midbrain; passageway carrying CSF through the midbrain, as part of the ventricular system
Cerebral peduncle — descending cortical fibers in the "basal" (ventral) portion of the midbrain, sometimes includes the substantia nigra (located immediately behind)
Cerebrospinal fluid (CSF) — fluid in the ventricles, and in the subarachnoid space and cisterns
Cerebrum — includes the cerebral hemispheres and diencephalon
but not the brainstem and cerebellum
Cervical — referring to the neck region; the part of the spinal cord that supplies the structures of the neck; C1–C7 vertebral; C1–C8 spinal segments
Chorda tympani — part of the 7th cranial nerve (CN VII) (see facial nerve); carrying taste from anterior two-thirds of tongue and parasympathetic innervation to glands
Chorea — a motor disorder characterized by abnormal, irregular, spasmodic, jerky, uncontrollable movements of the limbs or facial muscles, thought to be caused by degenerative changes in the basal ganglia
Choroid — a delicate membrane; choroid plexuses are found in the ventricles of the brain
Choroid plexus — vascular structure consisting of pia with blood vessels, with a surface layer of ependymal cells; responsible for the production of CSF
Cingulum — a bundle of association fibers in the white matter under the cortex of the cingulate gyrus; part of Papez (limbic) circuit
Circle of Willis — anastomosis between internal carotid and basilar arteries, located at the base of the brain, surrounding the pituitary gland
Cistern(a) — expanded portion of subarachnoid space containing CSF, e.g., cisterna magna (cerebello-medullary cistern), lumbar cistern
Claustrum — a thin sheet of gray matter, of unknown function, situated between the lentiform nucleus and the insula
Clonus — abnormal sustained series of contractions and relaxations following stretch of the muscle; usually elicited in the ankle joint; present following lesions of the descending motor pathways, and associated with spasticity
Conjugate eye movement — coordinated movement of both eyes together, so that the image falls on corresponding points of both retinas
CNS — abbreviation for central nervous system
Colliculus — a small elevation; superior and inferior colliculi comprising the tectum of the midbrain; also facial colliculus in the floor of the fourth ventricle
Commissure — a group of nerve fibers in the CNS connecting structures on one side to the other across the midline (e.g., corpus callosum of the cerebral hemispheres; anterior commissure)
Consensual reflex — light reflex; refers to the bilateral response of the pupil after shining a light in one eye
Contralateral — on the opposite side (e.g., contralateral to a lesion)
Corona radiata - fibers radiating from the internal capsule to various parts of the cerebral cortex — a term often used by neuroradiologists
Corpus callosum — The main (largest) neocortical commissure of the cerebral hemispheres
Corpus striatum — caudate, putamen, and globus pallidus, nuclei inside cerebral hemisphere, with motor function; the basal ganglia
Cortex — layers of gray matter (neurons and neuropil) on the surface of the cerebral hemispheres (mostly six layers) and cerebellum (three layers)
Cortico-bulbar — descending fibers connecting motor cortex with motor cranial nerve nuclei and other nuclei of brainstem (including reticular formation)
Corticofugal fibers — axons carrying impulses away from the cerebral cortex
Corticopetal fibers — axons carrying impulses toward the cerebral cortex
Cortico-spinal tract — descending tract, from motor cortex to anterior (ventral) horn cells of the spinal cord (sometimes direct); also called pyramidal tract
Cranial nerve nuclei — collections of cells in brainstem
giving rise to or receiving fibers from cranial nerves (CN III–XII); may be sensory, motor, or autonomic
Cranial nerves — twelve pairs of nerves arising from the brain and innervating structures of the head and neck (CN I is actually a CNS tract)
CSF — cerebrospinal fluid, in ventricles and subarachnoid space (and cisterns)
Cuneatus (cuneate) — sensory tract (fasciculus cuneatus) of the dorsal column of spinal cord, from the upper limbs and body; cuneate nucleus of medulla
Decerebrate posturing (rigidity) — characterized by extension of the upper and lower limbs; lesion at the brainstem level between the vestibular nuclei and the red nucleus
Decorticate posturing (rigidity) — characterized by extension of the lower limbs and flexion of the upper; lesion is located above the level of the red nucleus
Decussation — the point of crossing of CNS tracts, e.g., decussations of the pyramidal (cortico-spinal) tract, medial lemnisci, and superior cerebellar peduncles
Dementia — progressive brain disorder that gradually destroys a person's memory, starting with short-term memory, and loss of intellectual ability, such as the ability to learn, reason, make judgments, and communicate, and finally, inability to carry out normal activities of daily living; usually affects people with advancing age
Dendrite — receptive process of a neuron; usually several processes emerge from the cell body, each of which branches in a characteristic pattern
Dendritic spine — cytoplasmic excrescence of a dendrite and the site of an excitatory synapse
Dentate — (toothed or notched) dentate nucleus of the cerebellum (intracerebellar nucleus); dentate gyrus of the hippocampal formation
Dermatome — a patch of skin innervated by a single spinal cord segment (e.g., T1 supplies the skin of the inner aspect of the upper arm; T10 supplies umbilical region)
Descending tract — central motor pathway (e.g., from cortex to brainstem or spinal cord)
Diencephalon — consisting of the thalamus, epithalamus (pineal), subthalamus, and hypothalamus
Diplopia — double vision; a single object is seen as two objects
Dominant hemisphere — the hemisphere responsible for language; this is the left hemisphere in about 85 to 90% of people (including left-handed individuals)
Dorsal column — fasciculus gracilis and fasciculus cuneatus of the spinal cord, pathways (tracts) for discriminative touch, conscious proprioception and vibration
Dorsal root — afferent sensory component of a spinal nerve, located in the subarachnoid (CSF) space
Dorsal root ganglion (DRG) — a group of peripheral neurons along the dorsal root, whose axons carry afferent information from the periphery; their central process enters the spinal cord
Dura — dura mater, the thick external layer of the meninges (brain and spinal cord)
Dural venous sinuses — large venous channels for draining blood from the brain; located within dura of the meninges
Dysarthria — difficulty with the articulation of words
Dyskinesia — purposeless movements of the limbs or trunk, usually due to a lesion of the basal ganglia; also difficulty in performing voluntary movements
Dysmetria — impairment of the ability to control the range of movement in muscular action, causing under- or overshooting of the target (usually associated with cerebellar lesions)
Dysphagia — difficulty with swallowing
Dyspraxia — Impaired ability to perform a voluntary act previously well performed, with intact movement, coordination, and sensation
Efferent — away from the central nervous system; usually means motor to muscles
Emboliform — emboliform nucleus of the cerebellum, one of the intracerebellar (deep cerebellar) nuclei; with globose nucleus forms the interposed nucleus
Entorhinal — associated with olfaction (smell); the entorhinal area is the anterior part of the parahippocampal gyrus, adjacent to the uncus
Ependyma — epithelium lining of ventricles of the brain and central canal of spinal cord; specialized tight junctions at the site of the choroid plexus
Extrapyramidal system — an older clinically used term, usually intended to include the basal ganglia portion of the motor systems and not the pyramidal (cortico-spinal) motor system
Facial nerve — 7th cranial nerve (CN VII); motor to muscles of facial expression; carries taste from anterior twothirds of tongue; also parasympathetic to two salivary glands, lacrimal and nasal glands (see also chorda tympani)
Falx — dural partition in the midline of the cranial cavity; the large falx cerebri between the cerebral hemispheres, and the small falx cerebelli
Fascicle — a small bundle of nerve fibers
Fasciculus — a large tract or bundle of nerve fibers
Fasciculus cuneatus — part of dorsal column of spinal cord; ascending tract for discriminative touch, conscious proprioception and vibration from upper body and upper limb
Fasciculus gracilis — part of dorsal column of spinal cord; ascending tract for discriminative touch, conscious proprioception and vibration from lower body and lower limb
Fastigial nucleus — one of the deep cerebellar (intracerebellar) nuclei
Fiber — synonymous with an axon (either peripheral or central)
Flaccid paralysis — muscle paralysis with hypotonia due to a lower motor neuron lesion
Flocculus — lateral part of flocculonodular lobe of cerebellum (vestibulocerebellum)
Folium (plural folia) — a flat leaf-like fold of the cerebellar cortex
Foramen — an opening, aperture, between spaces containing CSF (e.g., Monro, between lateral ventricles and third ventricle; Magendie, between fourth ventricle and cisterna magna; Luschka, lateral foramen of fourth ventricle)
Forebrain — anterior division of embryonic brain; cerebrum and diencephalon
Fornix — the efferent (noncortical) tract of the hippocampal formation, arching over the thalamus and terminating in the mammillary nucleus of the hypothalamus and in the septal region
Fourth (4th) ventricle — cavity between brainstem and cerebellum, containing CSF
Funiculus — a large aggregation of white matter in the spinal cord, may contain several tracts
Ganglion (plural ganglia) — a collection of nerve cells in the PNS — dorsal root ganglion (DRG) and sympathetic ganglion; also inappropriately used for certain regions of gray matter in the brain (i.e., basal ganglia)
Geniculate bodies — specific relay nuclei of thalamus — medial (auditory) and lateral (visual)
Genu — knee or bend; middle portion of internal capsule; genu of facial nerve
Glial cell — also called neuroglial cell; supporting cells in the central nervous system — astrocyte, oligodendrocyte, and ependymal — also microglia
Globus pallidus — efferent part of basal ganglia; part of the lentiform nucleus with the putamen; located medially
Glossopharyngeal nerve — 9th cranial nerve (CN IX); motor to muscles of swallowing and carries taste from posterior one-third of tongue; nerve for the gag reflex
Gracilis (gracile) — sensory tract (fasciculus gracilis) of the dorsal column of spinal cord; nucleus gracilis of medulla
Gray matter — nervous tissue, mainly nerve cell bodies and adjacent neuropil; looks "grayish" after fixation in formalin
Gyrus (plural gyri) — a convolution or fold of the cerebral hemisphere; includes cortex and white matter
Habenula — a nucleus of the limbic system, adjacent to the posterior end of the roof of the 3rd ventricle (part of the epithalamus)
Hemiballismus — violent jerking or flinging movements of one limb, not under voluntary control, due to a lesion of subthalamic nucleus
Hemiparesis — muscular weakness affecting one side of the body
Hemiplegia — paralysis of one side of the body
Herniation — bulging or expansion of the tissue beyond its normal boundary
Heteronymous hemianopia — loss of different halves of the visual field of both eyes, as defined by projection to the visual cortex of both sides; bitemporal for the temporal halves and binasal for the nasal halves
Hindbrain — posterior division of the embryonic brain; includes pons, medulla, and cerebellum (located in the posterior cranial fossa)
Hippocampus or hippocampus "proper" — part of limbic system; a cortical area "buried" within the medial temporal lobe, consisting of phylogenetically old (threelayered) cortex; protrudes into floor of inferior horn of lateral ventricle
Homonymous hemianopia — loss of the same visual field in both eyes (i.e., left or right) as defined by the projection to the visual cortex on one side — involving the nasal half of the visual field in one eye and the temporal half in the other eye; also quadrantanopia
Horner's syndrome — miosis (constriction of the pupil), anhidrosis (dry skin with no sweat), and ptosis (drooping of the upper eyelid) due to a lesion of the sympathetic pathway to the head
Hydrocephalus — enlargement of the ventricles, usually due to excessive accumulation of cerebrospinal fluid within the ventricles (e.g., obstruction)
Hypoglossal nerve — 12th cranial nerve (CN XII); motor to muscles of the tongue
Hypo/hyper reflexia — decrease (hypo) or increase (hyper) of the stretch (deep tendon) reflex
Hypo/hyper tonia — decrease or increase of the tone of muscles, manifested by decreased or increased resistance to passive movements
Hypokinesia — markedly diminished movements (spontaneous)
Hypothalamus — a region of the diencephalon that serves as the main controlling center of the autonomic nervous system and is involved in several limbic circuits; also regulates the pituitary gland
Herpes (zoster, simplex) — a virus that attacks nerve root sheath and manifests itself as a rash with blisters soreness (see Neuralgia)
Infarction — local death of an area of tissue due to loss of its blood supply
Infundibulum (funnel) — infundibular stem of the posterior pituitary (neurohypophysis)
Innervation — nerve supply, sensory and/or motor
Insula (island) — cerebral cortical area not visible from outside view and situated at the bottom of the lateral fissure (also called the island of Reil)
Internal capsule — white matter between lentiform nucleus and head of caudate nucleus, and thalamus; consists of anterior limb, genu and posterior limb Ipsilateral On the same side of the body (e.g., ipsilateral
to a lesion)
Ischemia — a condition in which an area is not receiving an adequate blood supply
Ischemic penumbra — a region adjacent to or surrounding an area of infarcted brain tissue that is not receiving sufficient blood; the neurons may still be viable
Ischemia — reduction of blood flow in organs or tissues of a living organism (see Stroke, microstroke)
Kinesthesia — the conscious sense of position and movement
Lacune — a pathological small "hole" remaining after an infarct in the internal capsule; also irregularly-shaped venous "lakes" or channels draining into the superior sagittal sinus
Lateral ventricle — CSF cavity in each cerebral hemisphere; consists of anterior horn, body, atrium (or trigone), posterior horn, and inferior (temporal) horn
Lemniscus — a specific pathway in CNS (medial lemniscus for discriminative touch, conscious proprioception, and vibration; lateral lemniscus for audition)
Lentiform — lens-shaped; lentiform nucleus, a part of the corpus striatum; also called lenticular nucleus; composed of putamen (laterally) and globus pallidus
Leptomeninges — arachnoid and pia mater, part of meninges
Lesion — any injury or damage to tissue (e.g., vascular, traumatic)
Limbic system — part of brain associated with emotional behavior
Locus ceruleus — a small nucleus located in the uppermost pons on each side of the fourth ventricle; contains melanin-like pigment, visible as a dark-bluish area in freshly sectioned brain
Lower motor neuron — anterior horn cell of spinal cord and its axon; also the cells in the motor cranial nerve nuclei of the brainstem; called the alpha motor neuron; its loss leads to atrophy of the muscle and weakness, with hypotonia and hyporeflexia; also fascicluations are to be noted
Mammillary — mammillary bodies; nuclei of the hypothalamus that are seen as small swellings on the ventral surface of diencephalon (also spelled mamillary)
Massa intermedia — a bridge of gray matter connecting the thalami of the two sides across third ventricle; present in 70% of human brains (also called the inter-thalamic adhesion)
Medial lemniscus — brainstem portion of sensory pathway for discriminative touch, conscious proprioception and vibration, formed after synapse (relay) in nucleus gracilis and nucleus cuneatus
Medial longitudinal fasciculus (MLF) — a tract throughout the brainstem and upper cervical spinal cord that interconnects visual and vestibular input with other nuclei controlling movements of the eyes and the head and neck
Medulla — caudal portion of the brainstem; may also refer to the spinal cord as in a lesion within (intramedullary) or outside (extramedullary) the cord
Meninges — covering layers of the central nervous system (dura, arachnoid, and pia)
Mesencephalon — the midbrain (upper part of the brainstem)
Microglia — the "scavenger" cells of the CNS, i.e., macrophages; considered by some as one of the neuroglia
Midbrain — part of the brainstem; also known as mesencephalon (the middle division of the embryonic brain)
Motor — associated with movement or response
Motor unit — a lower motor neuron, its axon, and the muscle fibers that it innervates
MRI/NMR — magnetic resonance imaging (nuclear magnetic resonance), a diagnostic imaging technique that uses an extremely strong magnet, not x-rays
Muscle spindle — specialized receptor within voluntary muscles that detects muscle length; necessary for the stretch/myotatic reflex (DTR); contains muscle fibers within itself capable of adjusting the sensitivity of the receptor
Myelin — proteolipid layers surrounding nerve fibers, formed in segments, which is important for rapid (saltatory) nerve conduction
Myelin sheath — covering of nerve fiber, formed and maintained by oligodendrocyte in CNS and Schwann cell in PNS; interrupted by nodes of Ranvier
Myelopathy — generic term for disease affecting the spinal cord
Myopathy — Generic term for muscle disease
Myotatic reflex — stretch reflex, also called deep tendon reflex (DTR); elicited by stretching the muscle; causes a reflex contraction of the same muscle; monosynaptic (also spelled myotactic reflex)
Myotome — muscle groups innervated by a single spinal cord segment; in fact, usually two adjacent segments are involved (e.g., biceps, C5 and C6)
Minimally invasive — the minimum volume inflicted injuries method of surgical treatment
Neocerebellum — phylogenetically newest part of the cerebellum, present in mammals and especially well developed in humans; involved in coordinating precise voluntary movements and also in motor planning
Neocortex — phylogenetically newest part of the cerebral cortex, consisting of six layers (and sublayers) characteristic of mammals and constituting most of the cerebral cortex in humans
Neostriatum — the phylogenetically newer part of the basal ganglia consisting of the caudate nucleus and putamen; also called the striatum
Nerve fiber — axonal cell process, plus myelin sheath, if present
Neuralgia — pain - severe, shooting, "electrical," along the distribution of a peripheral nerve (spinal or cranial)
Neuraxis — the straight longitudinal axis of the embryonic or primitive neural tube, bent in later evolution and development
Neuroglia — accessory or interstitial cells of the central nervous system; includes astrocytes, oligodendrocytes, ependymal cells, and microglial cells
Neuron — the basic structural unit of the nervous system, consisting of the nerve cell body and its processes — dendrites and axon
Neuropathy — disorder of one or more peripheral nerves
Neuropil — an area between nerve cells consisting of a complex arrangement of nerve cell processes, including axon terminals, dendrites, and synapses
Nociception — refers to an injurious stimulus causing a neuronal response; may or may not be associated with the sensation of pain
Node of Ranvier — gap in myelin sheath between two successive internodes; necessary for saltatory (rapid) conduction
Nucleus (plural nuclei) — an aggregation of neurons within the CNS; in histology, the nucleus of a cell
Nystagmus — an involuntary oscillation of the eye(s), slow in one direction and rapid in the other; named for the direction of the quick movement
Neurosurgery — the section of medicine dealing with the nerve disease, whose treatment was performed mainly by surgical methods
Neurology — a branch of medicine which studies the structure and function of the nervous system in health and disease, patterns of development
Oculomotor nerve — 3rd cranial nerve (CN III); motor to most muscles of the eye
Olfactory nerve — 1st cranial nerve (CN I); special sense of smell
Oligodendrocyte — a neuroglial cell, forms and maintains the myelin sheath in the CNS; each cell is responsible for several internodes on different axons
Optic chiasm(a) — partial crossing of optic nerves — nasal half of retina representing the temporal visual fields — after which the optic tracts are formed
Optic disc — area of the retina where the optic nerve exits; also the site for the central retinal artery and vein; devoid of receptors, hence the blind spot
Optic nerve — 2nd cranial nerve (CN II); special sense of vision; actually a tract of the CNS, from the ganglion cells of the retina until the optic chiasm
Osteoporosis — depression and cortical layers of spongy bone due to partial resorption of bone substance
Osteochondrosis — a group of mainly inflammatory diseases podhryaschevogo of long tubular bones and short bones apophyses arising from specific or (less often) non-specific infections of the bones and joints
Paleocortex — phylogenetically older cerebral cortex consisting of three to five layers
Papilledema — edema of the optic disc, visualized with an ophthalmoscope (also called a choked disc); usually a sign of abnormal increased intracranial pressure
Paralysis — complete loss of muscular action
Paraplegia — paralysis of both legs and lower part of trunk
Paresis — muscle weakness or partial paralysis
Paresthesia — spontaneous abnormal sensation (e.g., tingling; pins and needles)
Pathway — a chain of functionally related neurons (nuclei) and their axons, making a connection between one region of CNS and another; a tract (e.g., visual pathway, dorsal column-medial lemniscus sensory pathway)
Peduncle — a thick stalk or stem; a bundle of nerve fibers (cerebral peduncle of the midbrain; also three cerebellar peduncles — superior, middle, and inferior)
Perikaryon — the cytoplasm surrounding the nucleus of a cell; sometimes refers to the cell body of a neuron
Peripheral nervous system (PNS) — nerve roots, peripheral nerves and ganglia outside the CNS (motor, sensory, and autonomic)
PET — positron emission tomography; a technique used to visualize areas of the living brain that become "activated" under certain task conditions; uses very shortacting biologically active radioactive compounds
Pia (mater) — the thin innermost layer of the meninges, attached to the surface of the brain and spinal cord; forms the inner boundary of the subarachnoid space
Plexus — an interweaving arrangement of vessels or nerves
Pons (bridge) — the middle section of the brainstem that lies between the medulla and the midbrain; appears to constitute a bridge between the two hemispheres of the cerebellum
Projection fibers — bidirectional fibers connecting the cerebral cortex with structures below, including basal ganglia, thalamus, brainstem, and spinal cord
Proprioception — the sense of body position (conscious or unconscious)
Proprioceptor — one of the specialized sensory endings in muscles, tendons, and joints; provides information concerning movement and position of body parts (proprioception)
Prosody — vocal tone, inflection, and melody accompanying speech
Ptosis — drooping of the upper eyelid
Pulvinar — the posterior nucleus of the thalamus; functionally, involved with vision
Putamen — the larger (lateral) part of the lentiform nucleus, with the globus pallidus; part of the neostriatum with the caudate nucleus
Pyramidal system — named because the cortico-spinal tracts occupy pyramid-shaped areas on the ventral aspect of the medulla; may include cortico-bulbar fibers; the term pyramidal tract refers specifically to the corticospinal tract
Paralysis, plegia — lack of voluntary movements
Paresis — a weakening of voluntary movements
Psychotherapy — a complex therapeutic effect on emotions, judgments, and self-rights to:
- psychological adjustment of the psyche of people with mental disorders
- psychological assistance
Quadrigeminal — referring to the four colliculi of the midbrain; also called the tectum
Quadriplegia — paralysis affecting the four limbs (also called tetraplegia)
Radicular — refers to a nerve root (motor or sensory)
Ramus (plural rami) — the division of the mixed spinal nerve (containing sensory, motor, and autonomic fibers) into anterior and posterior
Raphe — an anatomical structure in the midline; in the brainstem, several nuclei of the reticular formation are in the midline of the medulla, pons, and midbrain (these nuclei use serotonin as the neurotransmitter)
Red nucleus — nucleus in the midbrain (reddish color in a fresh specimen)
Reflex — involuntary movement of a fixed nature in response to a stimulus
Reflex arc — consisting of an afferent fiber, a central connection, a motor neuron, and its efferent axon leading to a muscle movement
Reticular — pertaining to or resembling a net - reticular formation of brainstem
Reticular formation — diffuse nervous tissue, nuclei and connections, in brainstem; quite old phylogenetically
Rhinencephalon — in humans, refers to structures related to the olfactory system
Rigidity — abnormal muscle stiffness (increased tone) with increased resistance to passive movement of both agonists and antagonists (e.g., flexors and extensors), usually seen in Parkinson's disease; velocity independent
Root — the peripheral nerves - sensory (afferent, dorsal) and motor (efferent, ventral) — as they emerge from the spinal cord and are found in the subarachnoid space
Rostral — toward the nose, or the most anterior end of the neuraxis
Rubro — red; pertaining to the red nucleus, as in rubrospinal tract and cortico-rubral fibers
Reflex — reaction of the body caused by central nervous system during stimulation of the receptors by agents of internal or external environment
Receptor — a special sensitive education, perceiving and transforming stimuli from the external or internal environment and transmitting information about the active agent in the nervous system
Regeneration — the restoration of the body of lost or damaged organs and tissues, as well as restoration of the whole body of its parts
Saccadic — to jerk; extremely quick movements, normally of both eyes together (conjugate movement), in changing the direction of gaze
Schwann cell — neuroglial cell of the PNS responsible for formation and maintenance of myelin; there is one Schwann cell for each internode of myelin
Secretomotor — parasympathetic motor nerve supply to a gland
Sensory — afferent; to do with receiving information, from the skin, the muscles, the external environment, or from internal organs
Septum pellucidum — a double membrane of connective tissue separating the anterior horns of the lateral ventricles, situated in the median plane
Septal region — an area below the anterior end of the corpus callosum on the medial aspect of the frontal lobe that includes cortex and the septal nuclei
Somatic — used in neurology to denote the body, exclusive of the viscera (as in somatic afferent neurons from the skin and body wall); the word soma is also used to refer to the cell body of a neuron
Somatic senses — touch (discriminative and crude), pain, temperature, proprioception, and the "sense of vibration"
Somatotopic — the orderly representation of the body parts in CNS pathways, nuclei, thalamus, and cortex; topographical representation
Somesthetic — consciousness of having a body; somesthetic senses are the general senses of touch, pain, temperature, position, movement, and "vibration"
Spasticity — velocity-dependent increased tone and increased resistance to passive stretch of the antigravity muscles; in humans, flexors of the upper limb and extensors of the lower limb; usually accompanied by hyperreflexia
Special senses — sight (vision), hearing (audition), balance (vestibular), taste (gustatory), and smell (olfactory)
Spinal accessory nerve — 11th cranial nerve (CN XI); refers usually to the part of the nerve that originates in the upper spinal cord (C1–5) and innervates the muscles of the neck, the sternomastoid and trapezius muscles
Spinal shock — complete "shut down" of all spinal cord activity (in humans) following an acute complete lesion of the cord (e.g., severed cord after a diving or motor vehicle accident); usually up to two to three weeks in duration
Spino-cerebellar tracts — ascending tracts of the spinal cord, anterior and posterior, for "unconscious" proprioception to the cerebellum
Spino-thalamic tracts — ascending tracts of the spinal cord for pain and temperature (lateral) and nondiscriminative or light touch and pressure (anterior)
Split brain — a brain in which the corpus callosum has been severed in the midline, usually as a therapeutic measure for intractable epilepsy
Stereognosis — the recognition of an object using the tactile senses and also central processing, involving association areas especially in the parietal lobe
Strabismus — a squint; lack of conjugate fixation of the eyes; may be constant or variable
Stria — a slender strand of fibers (e.g., stria terminalis from amygdala)
Striatum — the phylogenetically more recent part of the basal ganglia (neostriatum) consisting of the caudate nucleus and the putamen (lateral portion of the lentiform nucleus)
Stroke — a sudden severe attack of the CNS; usually refers to a sudden focal loss of neurologic function due to death of neural tissue; mostly due to a vascular lesion, either infarct (embolus, occlusion) or hemorrhage
Subarachnoid space — space between arachnoid and pia mater, containing CSF (cerebrospinal fluid)
Subcortical — not in the cerebral cortex, i.e., at a functionally or evolutionary "lower" level in the CNS; usually refers to the white matter of the cerebral hemispheres, and also may include the basal ganglia
Subicular region — part of hippocampal formation; transitional cortex (three to five layers) between that of the hippocampus proper and the parahippocampal gyrus
Substantia gelatinosa — a nucleus of the gray matter of the dorsal (sensory) horn of the spinal cord composed of small neurons; receives pain and temperature afferents
Substantia nigra — a flattened nucleus in the midbrain with motor functions — consisting of two parts: the pars compacta with melanin pigment in the neurons (the dopamine neurons, which degenerate in Parkinson's disease), and the pars reticulata, which is an output nucleus
of the basal ganglia
Subthalamus — region of the diencephalon beneath the thalamus, containing fiber tracts and the subthalamic nucleus; part of the functional basal ganglia
Sulcus (plural sulci) — groove between adjacent gyri of the cerebral cortex; a deep sulcus may be called a fissure
Synapse — area of structural and functional specialization between neurons where transmission occurs (excitatory, inhibitory, or modulation), using neurotransmitter substances (e.g., glutamate, GABA); similarly at the neuromuscular junction (using acetylcholine)
Syringomyelia — a pathological condition characterized by expansion of the central canal of the spinal cord with destruction of nervous tissue around the cavity
Symptom — a sign of illness
Syndrome — a particular combination of symptoms of the disease (see symptom) caused by a single start
Tectum — the "roof" of the midbrain (behind the aqueduct) consisting of the paired superior and inferior colliculi; also called the quadrigeminal plate
Tegmentum — the "core area" of the brainstem, between the ventricle (or aqueduct) and the cortico-spinal tract; contains the reticular formation, cranial nerve and other nuclei, and various tracts
Telencephalon — rostral part of embryonic forebrain; primarily cerebral hemispheres of the adult brain
Tentorium — the tentorium cerebelli is a sheet of dura between the occipital lobes of the cerebral hemispheres and the cerebellum; its hiatus or notch is the opening for the brainstem — at the level of the midbrain
Thalamus — a major portion of the diencephalon with sensory, motor, and integrative functions; consists of several nuclei with connections to areas of the cerebral cortex
Third (3rd) ventricle — midline ventricle at the level of the diencephalon (between the thalamus of each side), containing CSF
Tic — brief, repeated, stereotyped, semipurposeful muscle contraction; not under voluntary control, although may be suppressed for a limited time
Tinnitus — persistent ringing or buzzing sound in one or both ears
Tomography — radiological images, done sectionally, including CT and MRI
Tone — referring to muscle, its firmness, and elasticity - normal, hyper, hypo - elicited by passive movement and also assessed by palpation
Tract — a bundle of nerve fibers within the CNS, with a common origin and termination, (e.g., optic tract, cortico-spinal tract)
Transient ischemic attack (TIA) — a nonpermanent focal deficit, caused by a vascular event; by definition, usually reversible within a few hours, with a maximum of 24 hours
Trapezoid body — transverse crossing fibers of the auditory pathway situated in the ventral portion of the tegmentum of the lower pons
Tremor — oscillating, "rhythmic" movements of the hands, limbs, head, or voice; intention (kinetic) tremor of the limb commonly seen with cerebellar lesions; tremor at rest commonly associated with Parkinson's disease
Trigeminal nerve — 5th cranial nerve (CN V); major sensory nerve of the head (face, eye, tongue, nose, sinuses); also supplies muscles of mastication
Trochlear nerve — 4th cranial nerve (CN IV); motor to the superior oblique eye muscle
Two-point discrimination — recognition of the simultaneous application of two points close together on the skin; distance varies with the area of the body (compare finger tip to back)
Tremor — involuntary oscillatory movement of the whole body or parts thereof
Uncus — an area of cortex - the medial protrusion of the rostral (anterior) part of the parahippocampal gyrus of the temporal lobe; the amygdala is situated deep to this area; important clinically as in uncal herniation
Upper motor neuron — neuron located in the motor cortex or other motor areas of the cerebral cortex or in the brainstem - giving rise to a descending tract to lower motor neurons in the brainstem (for cranial nerves) or spinal cord (for body and limbs)
Upper motor neuron lesion — a lesion of the brain (cortex, white matter of hemisphere), brainstem, or spinal cord interrupting descending motor influences to the lower motor neurons of the brainstem or spinal cord, characterized by weakness, spasticity, and hyperreflexia, and often clonus; usually accompanied by a Babinski response
Vagus — 10th cranial nerve (CN X); supplies motor fibers to the larynx; the major parasympathetic nerve to organs of the thorax and abdomen
Velum — a membranous structure; the superior medullary velum forms the roof of the fourth ventricle
Ventricles — cerebrospinal (CSF) fluid-filled cavities inside the brain
Vermis — unpaired midline portion of the cerebellum, between the hemispheres
Vertigo — abnormal sense of spinning, whirling, or motion, either of the self or of one's environment
Vestibulocochlear — 8th cranial nerve (CN VIII); special senses of hearing and balance (acoustic nerve is not really correct)
White matter — nervous tissue of CNS made up of nerve fibers (axons), some of which are myelinated; appears "whitish" after fixation in formalin
Please find some useful articles and links related to the work of our clinic:
- Glossary - a list of the most common medical terms;
- A dictionary of neurological signs - neurological signs and their meaning;
- Frequently Asked Questions - the most frequently asked patient questions;
- Anatomy of the spine - presented and illustrated the basic data on the structure of the spine and spinal cord;
- Anatomy of the nervous system - presented and illustrated the basic data on the structure of the brain and spinal cord and nerves;
- Rules for the preparation of the investigated to some diagnostic procedures;
- Rules for the care of people with disabilities - safe ways to care for immobile or infirm patients at home or in hospital.
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