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Neuroanatomy
PA school anatomy
128
Anatomy
Graduate
11/16/2009

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Term
reflex arc
Definition
-sensory fiber
-associated motor neuron
-resultant involuntary musculoskeletal contraction involved in a spinal reflex
Term
cervical and lumbar enlargements
Definition
sections of the spinal cord that serve (respectively) the upper and lower extremities
Term
filum terminale
Definition
pial-glial filament
anchors the conus medullaris to the coccyx
Term
spinal cord segment C2 & C3
Definition
neck
Term
segment C6
Definition
lateral forearm and thumb
Term
segment C8
Definition
ulnar side of hand and little finger
Term
segment T7
Definition
xyphoid process
Term
segment T10
Definition
umbilicus
Term
segment L1
Definition
pubic region
Term
segment L5
Definition
dorsal foot and big toe
Term
segment S1
Definition
lateral foot and little toe
Term
segments S2-S4
Definition
genitoanal region
Term
neuropil
Definition
neuron cell bodies
dendrites
synapses
found in gray matter
Term
where is the lateral horn found?
Definition
the intermediate gray zone in the gray matter of spinal cord levels T1-L2,3
Term
dorsal horn
Definition
aka sensory horn
contains interneurons
receives synapses from central processes of dorsal root ganglion cells
Term
substantia gelatinosa
Definition
a region of the dorsal horn that receives pain and temperature fibers
Term
Lissauer's tract
Definition
aka dorsolateral fasciculus; a small piece of white matter that is related to the substantia gelatinosa; contains axons carrying pain and temperature one of two segment higher
Term
nucleus propius
Definition
constitutes the bulk of the posterior (dorsal) horn; contains interneurons that receive higher sensitivity signals from dorsal root ganglia
Term
what are the intermediolateral cell column neurons?
Definition
aka lateral horn; located in intermediate gray zone; neurons that give origin to preganglionic sympathetic fibers
Term
alpha motor neurons
Definition
located in the ventral horn; aka lower motor neurons
Term
gamma motor neurons
Definition
responsible for innervation of muscle spindles for the muscle stretch reflex; located in ventral horn
Term
funiculi
Definition
columns of white matter mass within the spinal cord; includes dorsal, lateral, and anterior funiculi
Term
fasciculi
Definition
smaller bundles of axons that are subdivisions of funiculi (column) white matter in the spinal cord; aka tracts; included long ascending fibers, long descending fibers, and propriospinal fibers
Term
long ascending fibers
Definition
carry sensory information projecting from spinal cord to thalamus, cerebellum, and brainstem nuclei
Term
long descending fibers
Definition
carry motor information to spinal cord from cerebral cortex, brainstem
Term
dorsal root ganglion
Definition
the location of cell bodies to which sensory information is brought; contains cell bodies of pseudounipolar sensory neurons and sensory receptors
Term
pseudounipolar sensory neurons
Definition
located in the dorsal root ganglion; divided into two processes: the peripheral process and the central process
Term
peripheral process of pseudounipolar sensory neuron
Definition
extends to sensory receptors or ends as free nerves in the periphery of the dorsal root ganglion; carries sensory information to the cell body (pseudounipolar neuron)
Term
central process of the pseudounipolar sensory neuron
Definition
enters the spinal cord to synapse with cells within the dorsal horn of the spinal gray matter; functions as an axon carrying information from the pseudounipolar sensory neuron to the synaptic ending in the spinal cord
Term
propriospinal fibers
Definition
a spinal tract (white matter) that interconnects various spinal cord levels and that functions in coordination of reflex activity
Term
how are discriminative touch and proprioception relayed?
Definition
via large diameter, heavily myelinated, rapidly conducting dorsal root ganglion cells; these cells have an axon collateral that ascends in the dorsal white column to higher levels
Term
how are pain and temperature relayed?
Definition
via small diameter, thinly-myelinated/non-myelinated, slow-conducting dorsal root ganglion cells that synapse with interneurons in the dorsal horn
Term
What two types of fibers arise from the anterior (ventral) horn?
Definition
Alpha motor neurons (skeletal muscle innervation) and gamma motor neurons (muscle spindle innervation)
Term
Gamma motor neurons
Definition
Term
Where are the axons of motor neurons of the autonomic nervous system located?
Definition
In the intermediolateral cell column of the intermediate gray of spinal cord segments T1-L2,3
Term
three spinal reflexes involving the limbs
Definition
1. muscle stretch (deep tendon) reflex
2. Golgi tendon organ reflex (inverse stretch)
3. Flexor withdrawal reflex
Term
muscle spindle
Definition
the receptor in the muscle involved in the muscle stretch reflex
Term
monosynaptic reflex
Definition
i.e. the muscle stretch reflex; one synapse is involved
Term
primary somatosensory cortex
Definition
parietal lobe, postcentral gyrus, areas 3,1,2; receives projections from the thalamus. Damage results in sensory loss on contralateral side
Term
somatosensory association area
Definition
superior parietal lobule, areas 5 and 7, integrates somatosensory inputs to recognize body parts and position. Damage results in inability to recognize objects by touch, astereogenesis
Term
primary visual cortex
Definition
occipital lobe, area 17. Lesion results in loss of vision in contralateral visual field.
Term
visual association area
Definition
areas 18, 19. Interpreting visual impressions and integrating visual inputs with other sensory inputs, i.e. seeing colors and detecting motion.
Term
Primary auditory cortex
Definition
located in the temporal lobe at the transverse gyri of Heschl, area 41. Bilateral lesions result in deafness. Unilateral lesion produces difficulty localizing sounds and distinguishing sounds from background noise. Hearing deficits mainly in contralateral ear.
Term
Auditory association cortex
Definition
area 22, superior temporal gyrus, understanding what is heard
Term
Wernicke's area
Definition
parietal and temporal lobes, areas 39, 40, 22 (auditory association). Damage in dominant cerebral hemisphere results in aphasia = difficulty understanding speech and producing speech that can be understood.
Term
Broca's area
Definition
inferior frontal gyrus, areas 44, 45 in dominant cerebral hemisphere. Lesions result in difficulty producing fluent sentences, telegraphic speech.
Term
Dominant hemisphere for language
Definition
left hemisphere for right-handed patient. Variable for left-handed patients
Term
primary motor cortex
Definition
precentral gyrus, area 4. Receives input from the thalamus
Term
Prefrontal cortex
Definition
9,10,11,12. Anterior end of the frontal lobe. Higher intellectual capacities such as planning, ambition, drive, and personality. Lesion results in loss of ambition and personality
Term
symptoms of cerebellar lesion
Definition
disequilibrium: inability to maintain proper balance
hypotonia: decreased muscle tone and difficulty maintaining posture
asynergia: lack of coordination of muscles which usually work together
ataxia: inability to coordinate voluntary movements
intention tremor: most apparent during a planned movement just prior to reaching the target
dysmetria: patient tends to overshoot or undershoot target
Term
flocconodular lobe of cerebellum
Definition
vestibulocerebellum; major inputs from vestibular system
Term
anterior lobe of cerebellum
Definition
spinocerebellum, major inputs from spinal cord
Term
posterior lobe of cerebellum
Definition
cerebrocerebellum/neocerebellum; inputs mainly from cerebral cortex via pons
Term
inferior cerebellar peduncle
Definition
contains fibers entering the cerebellum, and outputs to medulla oblongata, vestibular nuclei, and reticular formation; attaches cerebellum to medulla oblongata
Term
middle cerebellar peduncle
Definition
contains fibers entering the cerebellum from the pons; attaches the cerebellum to the pons
Term
superior cerebellar peduncle
Definition
contains outputs of cerebellum to the red nucleus and VA/VL thalamus
Term
deep cerebellar nuclei (4)
Definition
1. fastigial nucleus 2. globose nucleus 3. emoboliform nucleus 4. dentate nucleus
Term
Mossy fibers
Definition
originate from neurons in spinal cord, reticular formation, vestibular system, and pons;
Synapse with granule cells;
send collateral axons to deep cerebellar nuclei neurons;
excitatory
Term
climbing fibers
Definition
originate from neurons in the inferior olive; synapse mainly on dendrites of Purkinje cells in the molecular layer; send collateral axons to deep cerebellar nuclei neurons; excitatory
Term
Molecular layer of cerebellar cortex
Definition
located next to surface of cerebellum under the pia mater; large bundles of parallel fibers and dendrites of the Purkinje cells
Term
Purkinje cell layer of cerebellar cortex
Definition
monolayer of Purkinje cell bodies; dendrites of purkinje cells spread out in the molecular layer where they receive excitatory synapses from parallel fibers and climbing fibers; Purkinje cell axons leave the cerebellar cortex to synapse on deep cerebellar nuclei neurons; all inhibitory
Term
Granular layer of cerebellar cortex
Definition
contains granule cells whose axons form the parallel fibers which run in the molecular layer and synapse on dendrites of Purkinje cells; parallel fibers are excitatory
Term
fastigial nucleus
Definition
lies close to the midline of the cerebellum; receives inputs from the Purkinje cells of the vermis, vestibular nuclei, and vestibular ganglion cells. Output mainly to vestibular nuclei and reticular formation. Concerned with extensor muscle tone and adjusting posture.
Term
Globose nucleus
Definition
consists of several small groups of grey matter found lateral to the fastigial nucleus; receives input from Purkinje cells in intermediate zone; Output to red nucleus mainly, also to VA/VL thalamus; concerned with flexor muscle tone and limb movements
Term
emboliform nucleus
Definition
wedge-shaped, grey matter found lateral to globose nucleus. Has the same inputs, outputs and functions as the globose nucleus.
Term
dentate nucleus
Definition
largest and most laterally places of deep cerebellar nuclei. Receives most inputs from Purkinje cells located in the lateral cerebellar hemispheres. Output goes to red nucleus and VA/VL thalamus. Concerned with coordinating somatic motor activity by influencing motor regions of cerebral cortex. Coordinates finger movements and skilled movements.
Term
petrous part of carotid artery
Definition
where internal carotid artery enters the carotid canal in the temporal bone
Term
cavernous part of internal carotid artery
Definition
where artery runs anteriorly in the cavernous sinus before making a hair-pin turn to enter the subarachnoid space
Term
carotid siphon
Definition
sinuous course taken by cavernous and cerebral parts of carotid artery; forms a U-shaped bend
Term
branches of internal carotid artery
Definition
opthalmic artery, anterior cerebral artery, middle cerebral artery, lenticulostriate arteries and penetrating arteries
Term
central retinal artery
Definition
the most important branch of the ophthalmic artery; obstruction of main artery or branches results in total or partial blindness
Term
anterior cerebral artery
Definition
-supplies medial surface of the frontal and parietal lobes of the brain; occlusion causes restricted contralateral motor and somatosensory deficits usually limited to distal portions of the lower limb
Term
middle cerebral artery
Definition
supplies virtually the entire lateral surface of the cerebral hemispheres;
supplies portions of basal ganglia and internal capsule and insula
occlusion causes major motor and somatosensory deficits, language deficits if left hemisphere is involved
Term
lenticulostriate and penetrating arteries
Definition
very small branches of middle cerebral arteries that supply deep structures of the diencephalon and telencephalon;
frequently involved in strokes with neurological deficits
Term
vertebral arteries
Definition
first branches off of subclavian arteries in neck;
S-shaped siphon before entering cranial cavity
Term
vertebrobasilar system
Definition
includes the vertebral arteries which fuse to form the basilar artery
Term
major branches of vertebral arteries
Definition
anterior spinal arteries, posterior spinal arteries, posterior inferior cerebellar arteries, medullary branches
Term
anterior spinal arteries
Definition
each joins its mate from the other side and runs caadually along ventral midline of spinal cord; anastomose with radicular arteries
Term
great radicular artery
Definition
aka artery of Adamkiewicz;
present at spinal cord level T12 to L2;
may supply entire caudal two thirds of the spinal cord
Term
posterior spinal arteries
Definition
supplies posterior third of dorsolateral aspect of the spinal cord on each side
Term
posterior inferior cerebellar arteries
Definition
aka PICA,
-inferior surface of the cerebellar hemispheres
-branches to much of the lateral medulla
Term
branches of basilar artery
Definition
anterior inferior cerebellar artery, superior cerebellar artery, pontine artery, posterior cerebral arteries
Term
anterior inferior cerebellar arteries
Definition
inferior surfaces of cerebellum
parts of caudal pons
Term
superior cerebellar arteries
Definition
superior surface of cerebellum
much of caudal midbrain and rostral pons
Term
pontine artery
Definition
includes labrynthine artery: supplies inner ear
Term
posterior cerebral arteries
Definition
portions of temporal lobe
medial aspect of occipital lobe (visual cortex)
posterior and lateral parts of thalamus and rostral midbrain
Term
Circle of Willis
Definition
includes posterior communicating artery
posterior cerebral artery
anterior communicating artery
anterior cerebral artery
-normal in less than 50% of people
Term
cerebral veins
Definition
-no valves, very thin walls
-pierce arachnoid mater and inner layer of dura
-includes great cerebral vein of Galen
Term
symptoms of MCA occlusion
Definition
-contralateral facial and arm weakness, hemiplegia
-contralateral facial and arm sensory deficits
-homonymous hemianopsia
-conjugate deviation of eyes ipsilateral to side of lesion
-Wernicke's or Broca's aphasia
-may include apraxia if dominant lobe is affected
Term
Anterior Cerebral artery occlusion
Definition
-contralateral leg weakness
-contralateral leg sensory deficits
-behavioral abnormalities
Term
Posterior cerebral artery occlusion
Definition

-contralateral homonymous hemianopsia with macular sparing

-contralateral hemiplegia due to damage of internal capsule

-ipsilateral 3rd nerve palsy

-contralateral sensory loss

Term
fasciculi of dorsal columns
Definition
fasciculus gracilius: lower limbs
fasciculus cuneatus: upper limbs
Term
medial lemniscus
Definition
axons from the cells of the dorsal column nuclei (gracilis and cuneatus) that ascend as the brainstem tract
Term
ventral posterolateral nucleus
Definition
where the fibers of the medial lemniscus carrying touch, vibration, and proprioceptive information synapse in the thalamus; responsible for conscious awareness of pain and temperature
Term
dorsal column signs
Definition
impaired vibration sense, inability to determine limb position, impaired stereognosis, impaired two point tactile discrimination, shuffling uncoordinated gait, Romberg's sign (fall toward side of lesion)
Term
spinothalamic tract
Definition
primary pathway for pain, temperature, and non-discriminative touch
Term
destination of axons of spinothalamic tract
Definition
contralateral brainstem reticular formation and thalamus
Term
spinocerebellar tracts
Definition
transmit non-conscious proprioception information about limb position, joint angles, and muscle tension and length to the cerebellum
Term
dorsal spinocerebellar tract
Definition
carries proprioceptive information from muscles spindles from the trunk and lower limbs;
use inferior cerebellar peduncle to enter the cerebellum; segments T1-L2
Term
ventral spinocerebellar tract
Definition
-carries information from Golgi tendon organs; axons cross in anterior white commissure and ascend in the contralateral ventral spinocerebellar tract; recross in midbrain and enter ipsilateral cerebellum via superior cerebellar peduncle (2 crossings of axons)
Term
cuneocerebellar tracts
Definition
dorsal root fibers from C2-T4;
synapse in lateral cuneate nucleus in medulla
Term
rostral cerebellar tract
Definition
axons arise from cells in intermediate fray of C4-C8
Term
functions of basal ganglia
Definition
planning, speed, motivation of movements; contributes to movements learned by repetition
Term
basal ganglia structures
Definition
caudate nucleus, putamen, globus pallidus
Term
striatum
Definition
caudate + putamen; receiving portion
-excitatory input from cortex, thalamus, and substantia nigra
Term
lentiform nucleus
Definition
putamen + globus pallidus
Term
putamen
Definition
receives organized inputs from primary motor and sensory cortical areas
Term
caudate nucleus
Definition
receives fibers from association cortex
Term
substantia nigra
Definition
uses dopamine as a transmitter for communication with cortex, thalamus, and striatum
Term
efferent output from basal ganglia to thalamus
Definition
inhibitory
Term
output from thalamus to cortex
Definition
excitatory
Term
Parkinson's disease
Definition
pronounced loss of dopamine in the striatum due to death of substantia nigra neurons;
akinesia (reduced initiation of movement)
bradykinesia
lack of facial movements
increased muscle resting tone
resting tremor
a HYPOKINETIC disorder
Term
Huntington's Disease
Definition
a HYPERKINETIC DISEASE
-loss of GABA neurons in striatum and frontal lobe of cortex
-rapid, involuntary movements of face, arms, legs
-rapid mental deterioration
Term
Hemiballismus
Definition
wild, flailing movements of arms and legs due to lesion in the subthalamic nucleus
Term
Tourette's syndrome
Definition
involuntary movements/tics and/or explosive inappropriate vocalizations
-dopamine-related condition in basal ganglia
Term
association fibers
Definition
connect various areas of cortex within the same hemisphere
Term
short association fibers
Definition
connect adjacent gyri
Term
long association fibers
Definition
connect distant areas of cortex; i.e. uncinate fasciculus, superior longitudinal fasciculus, arcuate fasciculus
Term
uncinate fasciculus
Definition
frontal to temporal
lobe connection
Term
superior longitudinal fasciculus
Definition
frontal, parietal and occipital cortices
Term
arcuate fasciculus
Definition
frontal and temporal lobes
Term
commissural fibers
Definition
interconnect corresponding structures on either side of the neuraxis
Term
corticofugal fibers
Definition
originate from cerebral cortex and project to outside targets
Term
corticopetal fibers
Definition
arise from outside the cerebrum and project to the cortex
Term
internal capsule
Definition
a large compact bundle of projection fibers; v-shaped and divided into three parts: anterior, posterior, and genu
Term
anterior limb of internal capsule
Definition
between caudate nucleus and lenticular nucleus; fibers interconnect anterior thalamic nuclei with areas of the frontal lobe and cingulate gyrus
Term
genu of internal capsule
Definition
located at the intersection of anterior and posterior limbs; contains corticonuclear fibers that arise in the precentral gyrus and project to the motor nuclei of cranial nerves; lesions give rise to motor deficits of cranial nerves
Term
posterior limb of internal capsule
Definition
between thalamus and lenticular nucleus; corticospinal tracts arising from motor cortex and projecting to contralateral spinal cord; optic radiations
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