Glossary

Question 1

abducens nerve

Answer 1

cranial nerve VI, which supplies motor impulses to abduct the eye

Question 2

abduction

Answer 2

movement of a body part away from the midline

Question 3

absolute refractory period

Answer 3

the short period of membrane unresponsiveness during the passage of an action potential; another action potential cannot be generated during this time.

Question 4

acceleration-deceleration injury

Answer 4

type of injury in which the head is accelerated and then suddenly stopped (e.g., motor vehicle accident)

Question 5

acquired childhood aphasia

Answer 5

language disorder in which cerebral insult halts or disturbs normal language development in a child.

Question 6

action potential (AP)

Answer 6

buildup of electrical current in the neuron.

Question 7

action tremor

Answer 7

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.

Question 8

adduction

Answer 8

movement of a body part toward midline.

Question 9

adequate stimulus

Answer 9

a mechanical, thermal, electrical, or chemical stimulus strong enough to change the cell membrane’s potential.

Question 10

adiadochokinesia

Answer 10

inability to perform rapid, alternating muscle movements

Question 11

afferent

Answer 11

traveling toward a center

Question 12

agnosia

Answer 12

lack of sensory recognition as the result of a lesion in the sensory association areas or association pathways of the brain.

Question 13

agraphia

Answer 13

acquired disorder of writing caused by brain injury.

Question 14

akinesia

Answer 14

absence or lack of movements

Question 15

alexia

Answer 15

acquired disturbance of reading caused by brain injury.

Question 16

alexia with agraphia

Answer 16

classic neurological syndrome of reading disorder in which damage has occurred to the angular gyrus and the surrounding areas.

Question 17

alexia without agraphia

Answer 17

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.

Question 18

allocortex

Answer 18

the older, original part of the cerebral cortex.

Question 19

alpha motor neurons

Answer 19

neurons allowing contraction of extrafusal fibers and that have their final common path in cranial and spinal nerves.

Question 20

Alzheimer’s disease

Answer 20

the most common type of dementia. Its most striking feature is progressive deterioration of cognitive functions; language disturbance is a major symptom.

Question 21

amyloid plaques

Answer 21

axonal endings associated with pathologic deposits of extracellular beta-amyloid. Found in the brain of patients with dementia of the Alzheimer’s type.

Question 22

amyotrophic lateral sclerosis (ALS)

Answer 22

a progressive, fatal motor neuron disease usually involving both the upper and lower motor neuron pathways. Also known as Lou Ghrig’s disease.

Question 23

analgesia

Answer 23

loss of the sensation of pain.

Question 24

anastomosis

Answer 24

a connection between two vessels; an opening created by surgery, trauma, or pathologic condition between two spaces of organs that are normally separate.

Question 25

anencephaly

Answer 25

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.

Question 26

anesthesia:

Answer 26

loss of feeling or sensation.

Question 27

aneurysm:

Answer 27

a sac formed by the dilation of the wall of an artery, a vein or the heart.

Question 28

angular gyrus

Answer 28

convolution in the left parietal lobe that is critical for language processing.

Question 29

anion

Answer 29

an ion carrying a negative charge as a result of a surplus of electrons.

Question 30

anistrophy

Answer 30

the property of being directionally dependent as opposed to isotropic with means identical properties in all directions.

Question 31

anomia

Answer 31

loss of the power to name objects or recognize and recall their names.

Question 32

anomic aphasia

Answer 32

an acquired disorder of language caused by brain damage in which the primary difficulty is with word retrieval.

Question 33

anoxia

Answer 33

condition marked by the absence of oxygen supply to organs or tissue.

Question 34

anterior horn cell

Answer 34

cell in the ventral portion in an H-shaped body of gray matter in the spinal cord associated with efferent pathways

Question 35

anterior spinothalamic tract

Answer 35

the uncrossed fibers of the spinothalamic tract, which carry sensations of light or crude touch.

Question 36

anterograde

Answer 36

transport of axons from the cell body toward the axon terminal.

Question 37

aphasia

Answer 37

acquired disorder of language cause by brain damage; may affect comprehension or expression of language in any modality (spoken, written, or gestural language).

Question 38

aphasic alexia

Answer 38

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)

Question 39

aphemia

Answer 39

an obsolete term for loss of the power of speech.

Question 40

apraxia

Answer 40

a disorder of learned movement distinct from paralysis, weakness and incoordination; results in a disturbance of motor planning.

Question 41

apraxia of speech (AOS)

Answer 41

disorder of programming the muscles of articulation in the absence of paralysis, weakness, and incoordinaiton.

Question 42

aprosodia

Answer 42

abnormal prosody (stress and intonation pattern in speech), usually resulting from damage to the non-dominant hemisphere.

Question 43

aqueduct of Sylvius

Answer 43

small tube or outlet in the midbrain connective the third and fourth ventricles.

Question 44

arachnoid mater

Answer 44

a thing membranous covering (meninges) of the brain and spinal cord that lies between the dura mater and the pia mater.

Question 45

arcuate fasciculus

Answer 45

long subcortical association tract connecting posterior and anterior speech-language areas in the cerebrum.

Question 46

areflexia

Answer 46

lacking normal reflexive response to an adequate stimulus.

Question 47

arteriosclerosis

Answer 47

a chronic disease characterized by abnormal thickening and hardening of the arterial walls, with resulting loss of elasticity.

Question 48

arteriovenous malformation (AVM)

Answer 48

congenital morphologic defect resulting in an abnormal cluster of arteries directly connecting to veins; often enlarges over time and is at risk of rupture.

Question 49

articulatory undershoot

Answer 49

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.

Question 50

association fiber tracts

Answer 50

the fiber bundles that form connections between and within the association areas of the brain.

Question 51

astereognosis

Answer 51

loss of the ability to recognize objects through touch along; caused by brain damage.

Question 52

asymmetrical tonic neck reflex (ATNR)

Answer 52

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.