Glossary Flashcards
abducens nerve
cranial nerve VI, which supplies motor impulses to abduct the eye
abduction
movement of a body part away from the midline
absolute refractory period
the short period of membrane unresponsiveness during the passage of an action potential; another action potential cannot be generated during this time.
acceleration-deceleration injury
type of injury in which the head is accelerated and then suddenly stopped (e.g., motor vehicle accident)
acquired childhood aphasia
language disorder in which cerebral insult halts or disturbs normal language development in a child.
action potential (AP)
buildup of electrical current in the neuron.
action tremor
rhythmic, oscillatory, involuntary movement affecting the outstretched upper limbs as well as other parts of the body and the voice. Also known as essential tremor, heredofamilial tremor.
adduction
movement of a body part toward midline.
adequate stimulus
a mechanical, thermal, electrical, or chemical stimulus strong enough to change the cell membrane’s potential.
adiadochokinesia
inability to perform rapid, alternating muscle movements
afferent
traveling toward a center
agnosia
lack of sensory recognition as the result of a lesion in the sensory association areas or association pathways of the brain.
agraphia
acquired disorder of writing caused by brain injury.
akinesia
absence or lack of movements
alexia
acquired disturbance of reading caused by brain injury.
alexia with agraphia
classic neurological syndrome of reading disorder in which damage has occurred to the angular gyrus and the surrounding areas.
alexia without agraphia
classic neurologic syndrome of reading disorder, usually caused by a left posterior cerebral artery occlusion in a right-handed person; the resulting infarct produces lesions in the splenium of the corpus callosum and the left occipital lobe.
allocortex
the older, original part of the cerebral cortex.
alpha motor neurons
neurons allowing contraction of extrafusal fibers and that have their final common path in cranial and spinal nerves.
Alzheimer’s disease
the most common type of dementia. Its most striking feature is progressive deterioration of cognitive functions; language disturbance is a major symptom.
amyloid plaques
axonal endings associated with pathologic deposits of extracellular beta-amyloid. Found in the brain of patients with dementia of the Alzheimer’s type.
amyotrophic lateral sclerosis (ALS)
a progressive, fatal motor neuron disease usually involving both the upper and lower motor neuron pathways. Also known as Lou Ghrig’s disease.
analgesia
loss of the sensation of pain.
anastomosis
a connection between two vessels; an opening created by surgery, trauma, or pathologic condition between two spaces of organs that are normally separate.
anencephaly
absence of the cranial vault at birth with the cerebral hemispheres completely absent or reduced to small masses attached to the base of the skull.
anesthesia:
loss of feeling or sensation.
aneurysm:
a sac formed by the dilation of the wall of an artery, a vein or the heart.
angular gyrus
convolution in the left parietal lobe that is critical for language processing.
anion
an ion carrying a negative charge as a result of a surplus of electrons.
anistrophy
the property of being directionally dependent as opposed to isotropic with means identical properties in all directions.
anomia
loss of the power to name objects or recognize and recall their names.
anomic aphasia
an acquired disorder of language caused by brain damage in which the primary difficulty is with word retrieval.
anoxia
condition marked by the absence of oxygen supply to organs or tissue.
anterior horn cell
cell in the ventral portion in an H-shaped body of gray matter in the spinal cord associated with efferent pathways
anterior spinothalamic tract
the uncrossed fibers of the spinothalamic tract, which carry sensations of light or crude touch.
anterograde
transport of axons from the cell body toward the axon terminal.
aphasia
acquired disorder of language cause by brain damage; may affect comprehension or expression of language in any modality (spoken, written, or gestural language).
aphasic alexia
a disorder of reading caused by brain damage; the reading disorder is part of the overall aphasia syndrome (for example, the reading disorder associated with Wernicke’s aphasia)
aphemia
an obsolete term for loss of the power of speech.
apraxia
a disorder of learned movement distinct from paralysis, weakness and incoordination; results in a disturbance of motor planning.
apraxia of speech (AOS)
disorder of programming the muscles of articulation in the absence of paralysis, weakness, and incoordinaiton.
aprosodia
abnormal prosody (stress and intonation pattern in speech), usually resulting from damage to the non-dominant hemisphere.
aqueduct of Sylvius
small tube or outlet in the midbrain connective the third and fourth ventricles.
arachnoid mater
a thing membranous covering (meninges) of the brain and spinal cord that lies between the dura mater and the pia mater.
arcuate fasciculus
long subcortical association tract connecting posterior and anterior speech-language areas in the cerebrum.
areflexia
lacking normal reflexive response to an adequate stimulus.
arteriosclerosis
a chronic disease characterized by abnormal thickening and hardening of the arterial walls, with resulting loss of elasticity.
arteriovenous malformation (AVM)
congenital morphologic defect resulting in an abnormal cluster of arteries directly connecting to veins; often enlarges over time and is at risk of rupture.
articulatory undershoot
speech production error in which the active articulatory structure (often the tongue) does not reach its target completely. Often a feature of the articulation of persons with hypokinetic dysarthria.
association fiber tracts
the fiber bundles that form connections between and within the association areas of the brain.
astereognosis
loss of the ability to recognize objects through touch along; caused by brain damage.
asymmetrical tonic neck reflex (ATNR)
a reflex, normal in the newborn, that consists of extension of the arm and sometimes of the leg on the side to which the head is forcibly turned, with flexion of the contralateral limbs. Considered abnormal if found beyond the 8th or 9th. month of age in a term infant.
