difficulties with arithmetic; may
be the result of damage to the angular gyrus in the hemisphere
dominant for speech and language
acceleration-deceleration
trauma:
According to Love and Webb (1992)
the most predominant injury type is acceleration-deceleration
trauma. Acceleration-deceleration trauma causes discrete lesions
which affect only certain areas of the brain, occurs when the head
is accelerated and then stopped suddenly, as in a car accident,
and causes discrete, focal lesions to two areas of the brain, The
prefrontal areas and the anterior portion of the temporal lobes.
The brain will suffer contusions at the point of direct impact and
at the site directly opposite the point of impact due to the
oscillation of the brain within the skull.
It should be noted that brain injuries may occur as a result of
acceleration-deceleration trauma unaccompanied
by impact.
acetylcholine:
a neurotransmitter for motor
neurons that is involved in the inhibitory function (as is
dopamine) of the basal ganglia
afferent
fibers:
nerve fibers that take messages
from the periphery to the brain; afferent fibers are almost always
sensory fibers
alexia:
acquired disturbance of reading
due to brain injury (Love and Webb, 1996, p. 314)
agnosia:
lack of sensory recognition as
the result of a lesion in the sensory association areas or
association pathways of the brain. An example is looking at a
common object but not recognizing it, or associating meaning with
the image.
agraphia:
acquired disturbance of writing
due to brain injury (Love and Webb, 1996, p. 314)
alexia with
agraphia:
difficulties with reading and
writing; may be the result of damage to the angular gyrus in the
hemisphere dominant for speech and language
alpha
cells:
the principle lower motor neurons
of the spinal cord (they are located on the ventral aspect of the
cord); they form the main part of the final common pathway and
conduct rapid motor impulses; each alpha cell innervates
approximately 200 muscle fibers
alternating
hemiplegia:
paralysis of different structures
on each side of the body; this condition may be the result of a
lesion in the brain stem that damages both the nucleus of a
cranial nerve and one side of the upper motor neurons of the
pyramidal tract
amygdala:
a structure which is attached to
the tail of the caudate nucleus; it is considered to be a part of
the limbic system and is involved in emotion
anastomosis:
communication or connection
between the separate components of a branching system; as in the
Circle of
Willis, anastomosis allows
blood carried by different arterial branches to come together and
be redistributed
angular gyrus:
the gyrus that lies near the
superior edge of the temporal lobe, and immediately posterior to
the supramarginal gyrus; it is involved in the recognition of
visual symbols (Geschwind referred to it as the "association
cortex for association cortices" and "the most important cortical
areas of speech and language"). Lesions in this area can result in
alexia
and agraphia.
anomia:
difficulty with word-finding or
naming; anomia may be the result of damage to the angular gyrus in
the hemisphere dominant for speech and language. According to
Goodglass and Kaplan (1983), anomia can be localized with the
least reliability of any of the aphasic syndromes. Also, according
to Keenan (1975) all patients with Aphasia experience some
problems with word finding.
anosmia:
a loss of the sense of smell; may
be a result of a lesion on the olfactory pathway
anterior:
toward the front (opposed to
posterior)
anterior
cerebral artery:
a branch of the internal carotid
artery; the anterior cerebral artery supplies blood to the medial
cortex, some areas of the frontal lobe, and the corpus
striatum
anterior
commissure:
one of the three major groups of
commissural fibers; part of the Circle of Willis, the anterior
commissure connects the temporal lobes, as well as connecting the
temporal lobe to the amygdala and to the opposite occipital lobe;
it is also connected to the corpus callosum
anterior
communicating artery:
an artery which arises from the
internal carotids; it joins together the anterior cerebral
arteries of each hemisphere
aorta:
the main artery supplying blood
to the body (with the exception of the lungs); it ascends from the
heart then forms an arch, from which two subclavian arteries
arise
aphasia:
a disturbance of the skills,
associations, and habits of language due to injury to certain
brain areas that are specialized for these functions. Disturbances
of language usage that are due to paralysis or incoordination of
the musculature of speech or writing or poor vision or hearing are
not, of themselves, aphasic." Thus, aphasia can affect auditory
comprehension, oral expression, reading and writing. (Goodglass
and Kaplan, 1983)
apraxia:
comes from the Greek word
"praxis," which means action. According to Halperin (1986 in
Chapey, 1986, p.422), "apraxia of speech is an articulation
disorder that results from impairment due to brain damage, of the
capacity to order the positioning of speech musculature and the
sequencing of muscle movements for volitional production of
phonemes and sequences of phonemes; but it is not accompanied by
significant weakness, slowness, or incoordination of these same
muscles in reflex and automatic acts."
Apraxia of speech is a disruption
of the capacity to program the skilled oral movements necessary
for speech. The problem is with the programming associated with
incorrect neural commands at higher, more central levels. In the
past, apraxia was often classified as a type of articulation
disorder and was in fact called central dysarthria by some. Now,
it is considered a motor planning/programming deficit. According
to Wertz (1984), apraxia of speech "is a neurogenic phonological
disorder, resulting from the sensorimotor impairment of the
capacity to select, program and execute coordinated movements of
the speech musculature for the production of voluntary speech." In
other words, the part of the brain that generates the motor
programs for speech/phonology is damaged. Kearns and Simmons
(1989, in Northern, 1989) reported that research using
spectographic analysis of voice onset time (VOT) supports the
programming position. Includes limb apraxia, oral apraxia, apraxia
of gait, and apraxia of the swallow.
apraxia of
gait:
difficulty with programming the
motor movements involved in walking
apraxia of the swallow :
inability to swallow
volitionally.
apical dendrites:
a type of dendrite which has a
stalk that is filled with cytoplasm, these appear to be part of
the soma of the neuron to which they are attached; the majority of
apical dendrites are found in the cerebral cortex
Aqueduct of Sylvius (cerebral
aqueduct):
a channel which connects the
third and fourth ventricles
arachnoid
mater:
the middle layer of the meninges;
in some areas it has projections (arachnoid granulations or villi)
into the sinuses formed by the dura mater
arachnoid villi (arachnoid
granulations):
projections of the arachnoid
mater into the sinuses formed by the dura mater that transfer
cerebrospinal fluid back into the bloodstream
arcuate fasciculus:
the groups of fibers that connect
Broca's area with Wernicke's area (these fibers connect to the
angular gyrus) and are located below the supramarginal gyrus.
According to Geschwind, damage to this area results in Conduction
Aphasia.
arteriosclerosis:
formation of "plaque" consisting
of muscle cells and fats on arterial walls making the flow of
blood through arteries more difficult. Informally,
"hardening of the arteries"
arteries of
stroke:
striata arteries, which are
branches of the middle cerebral arteries
the component of the reticular
formation that is responsible for the sleep-wake cycle; it
mediates various levels of alertness
aspiration:
occurs whenever food enters the
airway below the true vocal folds. Aspiration can occur
before, during, or
after the swallow.
association fibers:
nerve fibers that connect areas
within the same lobe or between lobes, within the same hemisphere;
the most prevalent type of neuroal tracts found in the
cortex
ataxia:
an incoordination of motor
movement; ataxia results from cerebellar lesions; the term may
also be used to describe the unsteady walk and unusual postures
seen in patients who have suffered injury to the cerebellum
ataxic dysarthria (cerebellar
dysarthria):
a disorder that results in jerky,
uncoordinated movements of the speech musculature; it is caused by
lesions in the cerebellum
athetosis:
disorder that causes slow
writhing movements of the entire body but especially of the arms,
face and tongue.
auditory
association areas:
Brodmann's areas 21 and 22
auditory
comprehension:
the ability to understand spoken
language
autonomic
nervous system:
one of the three main divisions
of the nervous system; it innervates the involuntary structures of
the body (e.g., heart, smooth muscles, glands) and is involved in
control of automatic and glandular functions; it is divided into
two parts, the sympathetic and parasypathetic
axon:
the part of the neuron that
allows it to send messages to other nerve cells; although each
neuron can have only one axon, the axon itself can have many
branches which connects it to many others
B
Barium:
contrast material, not
radioactive, used during barium and modified barium studies
basal
ganglia:
the largest subcortical structure
of the brain; it is made up of the caudate
nucleus and the
lenticular
nucleus; it is located at
the level of the thalamus
basilar artery
(vertebral basilar artery):
the artery that is formed when
the two vertebral arteries join together at the lower border of
the pons; the basilar artery again divides at the superior border
of the pons to form the posterior cerebral arteries (other
arteries that arise from the basilar prior to this division
include the anterior cerebellar arteries, inferior cerebellar
arteries, posterior cerebellar arteries, and the pontine
branches)
basilar dendrites:
a type of dendrite that does not
have a stalk; these are more numerous than apical dendrites
BDAE:
Boston Diagnostic Aphasia Examination
developed by Goodglass and Kaplan
in 1972, is currently being revised. (I was asked by the
publishing company to critique/review the upcoming edition. It
promises to be quite good.) At the moment it consists of
twenty-seven subtests divided into the following sections:
conversational and expository speech, auditory comprehension, oral
expression, understanding written language, and writing. The
severity of a patient's aphasia can be rated on a scale from one
to seven based on speech and language characteristics as well as
auditory comprehension. The Boston Naming Test, a test for anomia which was developed to be used
along with the BDAE, is the supplementary instrument most often
used in the evaluation of aphasia (Chapey, 1994).
bilateral
innervation:
both left and right nuclei of a
pair of cranial nerves receive innervation from both the left and
the right motor pyramidal tracts, provides both ipsilateral and
contralateral innervation
biological
intelligence:
the complex cognitive processes
(such as reasoning and judgment) that are mediated by the most
anterior part of the frontal lobe
BDAE: Boston Diagnostic
Aphasia Examination
bradycardia:
slowed heart rate
Bradykinesia:
the "reduced speed of movement of
a muscle through its range" (Love & Webb, 1992, p.
146).
brain
stem:
the midbrain, pons, and medulla
oblongata
bradycardia:
slow heart rate
broad-based gait:
a term used to describe the way
in which some patients compensate for problems related to
cerebellar injury by walking with their feet far apart
Broca's
aphasia:
affects the third frontal convolution (both the gyrus and the sulcus) of the
left frontal lobe. ( Broca's area,
Brodmann's area
#44)
Characteristics are
telegraphic speech,
affected syntax, as well as labored and slow speech,
Melodic
Contour is flat and
Articulatory
Agility is impaired.
Potential problems include: simplification of consonant clusters
(e.g. t/st, p/spl) and distortion of phonemes, substitutions are
infrequent. A few paraphasias
may occur. They will usually be literal.
Repetition is typically impaired, as is
Word
finding. Auditory Comprehension is superior to expressive language. The
patient's ability to understand grammatical morphemes will be
affected. So, while it can be said that auditory comprehension is
good in comparison to that of Wernicke's aphasics, it is
not normal.
The Token
Test (DeRenzi &
Vignolo, 1966), which assesses subtle receptive language
dysfunction, can be used to evaluate the auditory comprehension of
Broca's aphasics and to help distinguish between Broca's aphasia
and verbal apraxia. Also, limb apraxia may not allow the
patient to carry out the instructions, even though he/she
understands them.
Hemiplegia/Hemiparesis of the right side is common in left hemisphere
lesions causing Broca's aphasia (remember, the language center is
in the left hemisphere for more than 90% of the population) The
face and arm are most likely to be affected due to the
organization of the motor strip.Apraxia
frequently accompanies this type of aphasia as it is also caused
by lesions to area 44. Broca's aphasics typically have low
frustration tolerance. They are aware of their errors and may
respond to them with a catastrophic reaction which might include crying, screaming and yelling,
etc.
Broca's area:
the area of the brain involved in
the programming of motor movements for the production of speech
sounds; it is also involved in syntax; Broca's area is located on
the inferior third frontal gyrus in the hemisphere dominant for
language; injuries here may result in apraxia or Broca's
aphasia
Brodmann's Classification
System:
a map of the cortex developed by
neurologist Korbinian Brodmann that classifies the different areas
of the brain by number
buccinator muscle (oral
cavity):
holds food in contact with the
teeth. with the obicularis oris and zygomaticus all three
are innervated by the facial nerve (CN. VII).
bulbar lesions:
injuries to the nuclei of the
cranial nerves located in the brain stem; they are considered to
be lesions of the final common pathway: usually bilateral, they
produce bulbar palsy