Descending Pathways Flashcards
List the descending motor pathways
Corticospinal/Pyramidal tract
Extrapyramidal tracts
Which descending motor pathways controls :
Crude/ fine movement
And which part of the body?
Corticospinal/Pyramidal tract
- discrete and detailed movement
- especially distal segments of the limbs like fingers and hands
Extrapyramidal tracts
-executing gross movements of trunk and proximal limb muscless
Which descending motor pathways controls posture
Extrapyramidal tracts
most important output pathway from motor cortex is the ——— tract
Pyramidal tract
Pyramidal tract descend from motor cortex with only a little interruption to spinal cord
T/F
F
ORIGIN OF THE pyramidal tract FIBERS
- ____% from primary motor cortex
- ____% from premotor and supplemental motor area
- 40% from———
- ___% from ____
30
30
somatosenory cortex
3; bertz cells
pyramidal cells are in the —— lamina of—— lobe
5th
parietal
bertz cells are ——cells that give rise to ——-fibers with a mean diameter of about—— and transmit impulse at a velocity of____
giant pyramidal
large myelinated
60um
70m/sec
other fibers of the pyramidal tract beside the bertz cells are less than——- in diameter
4um
COURSE OF PYRAMIDAL TRACTS
- motor area to ——- limb of ————-and then through—— to—— of the——( to —- nuclei) to——-to spinal cord
- most of the fibers terminate on—— and only few terminate——-
Posterior
internal capsule
crus cerebri
cerebral peduncle
pons; pontine
medulla pyramids
interneurones; directly on the anterior horn cells
——% —— of the ——- pyramidal tracts occur in at the medullary pyramids while the ——— pyramidal tracts go ——-
80
decussation
Lateral
Anterior
Ipsilateral
pontine nuclei sends fibers that passes through the—— to inform the—— of the action about to happen
middle cerebellar peduncle
contralateral cerebellum
some collateral cortico——-/——- fibers from the pyramidal tracts go to motor nuclei of some cranial nerves
bulbar; corticonuclear
Lateral pyramidal tracts control muscle that move ——- and ——-
Anterior pyramidal tracts control muscle that move ——— and ——-
Arms and legs
Axial and proximal limb
Proxima limb / ——- muscles
Postural
Anterior pyramidal tracts decussate eventually.
T/F
T
uppermotor neuron lesion
-can cause:
—-paralysis
——-
——-(enhanced—— reflex) in the absence of muscle atrophy
spastic
hypertonicity
hyperreflexia; stretch
lowermotor neuron lesion -can cause ——paralysis muscular—— ———stretch reflex
flaccid
atrophy
absent or reduced
Flaccid paralysis causes your muscles to—— and become—-. It results in——-
shrink; flabby
muscle weakness.
Spastic paralysis involves—— and—— muscles. It can cause your muscles to——-, or—-
tight; hard
twitch uncontrollably
spasm
The stretch reflex or—- reflex refers to the—— of a muscle in response to its—- stretching
myotatic
contraction
passive
Extrapyramidal tracts
-these include all descending motor pathways that comes from the brain and act on skeletal muscles but———
do not pass through the medullary pyramids
The vestibular nuclei are located in the—— and—- of the hindbrain
Red nucleus is located in the ——-
Location of reticular formation
medulla
pons
Midbrain
Through the whole brainstem
In extra pyramidal tract,
motor cortex,——,and——, all send axons that terminate in the—— where they synapse with motor nuclei of the——, the———, and——-
basal ganglia
cerebellum
brainstem
vestibular nuclei
red nucleus
In extrapyramidal pathway
Vestibulospinal(——motor neuron)(ipsi)
Reticulospinal(——motor neuron)(—-)
Rubrospinal(——motor neuron)(——)
alpha
gamma; ipsi
alpha; contra
in voluntary movements, there is co activation of alpha and gamma efferents
T/F
T
THE CEREBELLUM
-function includes—— and—— of movement of the body vital to control of——-
coordination; control
rapid muscular movements
The cerebellum initiates and modulates the tone and movements of joints
T/F
F. Doesn’t initiate
ANATOMICAL FUNCTIONAL AREAS of cerebellum
- divided into 3 lobes by 2—-
- anterior lobe(——cerebellum)
- posterior lobe( ——cerebellum)
- ____lobe(——cerebellum)
deep fissures
paleo
neo
flocullonodular; Archi
Cerebellum divided based on contribution from other parts of the motor system
- ____cerebellum
- _____cerebellum
- ____cerebellum
spino
cerebro
vestibulo
Cerebellum divided based on contribution from other parts of the motor system
- spinocerebellum :_____ +——- that receives info from the spinal cord
- cerebrocerebellum :——— that receives input from cerebral cortex
- vestibulocerebellum :____ is functionally related to the vestibular apparatus
whole anterior lobe; parts of posterior lobe
remaining part of posterior lobe
flocullonodular node
FUNCTIONAL AREAS of cerebellum
-_____
-____:divided into___ and____ zones
vermis
2 cerebral hemispheres
lateral
intermediate
FUNCTIONAL AREAS of cerebellum
- vermis:
- most cerebellar control of muscle movements of the_____ are located here
intermediate zones:
-control of muscular contractions in the——-
lateral zone:
-involved in overall planning of—— movements.
neck , axial body, shoulder and hips
distal portions of upper and lower limb like fingers , toes, hands, feet
sequential motor
Without the lateral zone of the cerebellum, most—— motor activities loose their—— and become——-
discrete
appropriate timing
incoordinate
BASAL GANGLIA
- ____input is from—-
- ___output goes to____
almost all ; cortex
all; cortex
List the Make up of basal ganglia —— ——- ——- ———
Caudate nuclei
Lenticular nuclei
Subthalamic nucleus
Substantial nigra
Lenticular nuclei is divided into :
——and——-(—-)
putamen
globus pallidus; pallidum
Subthalamic nucleus aka——-
body of leys)
_____+____ = dorsal striatum and the space between them is called the____
caudate nucleus
putamen
internal capsule
FUNCTIONS OF basal ganglia
- associates with pyramidal tract to control——- like——
- damage to basal ganglia produces—— writing patterns
- also involved in planning and programming of movement
complex patterns of motor activity
writing the alphabet
crude
LESIONS IN PARTS OF BASAL GANGLIA
(A) Globus pallidus:
-causes___ which is the______ and being unable to maintain____
(B) Subthalamus:
-cause_____ which is the_____
(C) Internal capsule:
-____which is the_______
(D) Substantial nigra:
-_____,xterized by_____
Athetosis; spontaneous writhing movement of a hand,arm, the neck, or face; postural support
hemiballismus; sudden or spontaneous , wild flinging ballistic movements of the limbs
Huntington’s chorea; flicking movement in the hand, face, or any other parts of the body
Parkinson’s disease; rigidity, hypokinesia, tremors
Difference between athetosis and chorea
Chorea typically involves the face, mouth, trunk, and limbs. Athetosis is a continuous stream of slow, flowing, writhing involuntary movements. It usually affects the hands and feet.
BRAIN STEM
- consist of____,___,___
- kind of an extension of____ into the____
mid brain; pons; medulla
spinal cord; cranial cavity
Brain stem contains only motor nuclei.
T/F
F. -contains motor and sensory nuclei
Location of pontine medullary nuclei
located in the pons but extends into the mid brain
PONTINE RETICULAR NUCLEI
- transmits—— signals to the cord through the pontine /———tract
- the fibers terminate on the——- neurons that—- the muscles that——
- receive—— signals from local circuits within the brainstem and also from—— and——-
excitatory
medial retuculospinal
medial anterior motor
excite
support the body against gravity
excitatory; vestibular; deep nuclei of cerebellum
control respiration
- control CVS
- control GI system
- control many stereotyped movements of the body
- control of eye movement
- control of equilibrium
Are all functions of ——
Brain stem
MEDULLARY RETICULAR NUCLEI
- transmits—— signals to the same ——-through the medullary/——-tract
- they also receive strong collaterals from——- tracts,—— tracts, and other motor pathways
- excitation of this—— pathway allows the muscles that are—— to——- that would be impossible if the antigravity muscles opposed the necessary movements
inhibitory; antigravity anterior motor neurons
lateral reticulospinal
corticospinal; rubrospinal
inhibitory; inhibited; perform other motor activities
Which on the reticulospinal tracts have high degree of natural excitability ?
Pontine
VESTIBULAR NUCLEI
-functions with—— to——- the antigravity muscles through the ——of the cord
-the vestibular nuclei’s role is to control selectively the excitatory signals to the different antigravity muscles to maintain equilibrium in response to signals from vestibular apparatus (learn this Iseoluwa)
pontine; excite
anterior columns
pontine reticular
without the support of the vestibular nuclei, the pontine reticular system doesn’t lose any of its force.
T/F
F. without the support of the vestibular nuclei, the pontine reticular system loses much of its force
CLINICAL ABNORMALITIES OF CEREBELLUM
- ataxia:——-
- intention tumor:——-
- hypotonia:——-
- Dysmetria : inability to—- leading to——
- asthenia:——
- rebound :———
- Dysarthria:——-
- Dysdiadochokinesia:——-. E.g——-
staggering gait
tremor at rest and initiation of movement
reduced muscle tone
judge distance; past- pointing
reduced force of phasic movement
loss of damping function of cerebellum
slurring of speech
inability to perform rapidly alternating movements; turning the palm front and bank or arm up and down
Pontine tract works on —- muscles while medullary tract works on —— muscles
Extensor
Flexor
for eye movements requiring fine control, motoneurons innervate alot of muscle fibers
T/F
F… only a few muscle fibers
For postural muscles involved in large movements, motoneurons innervate thousands of muscle fibers
T/F
T
A motoneuron pool is the———
set of motoneurons innervating fibers within the same muscle.
There are two types of motoneurons: —— motoneurons and —— motoneurons
α
γ
α Motoneurons innervate——— skeletal muscle fibers.
γ Motoneurons innervate specialized——- muscle fibers
extrafusal
intrafusal
α Motoneurons and γ motoneurons are coactivated .
T/F
T
Muscle spindles are especially abundant in muscles utilized for——- movements
fine
There are two types of intrafusal fibers present in muscle spindles:——- fibers and ———fibers
nuclear bag
nuclear chain
both types of fibers are present in every muscle spindle
T/F
T
Generally, which fibers are more, nuclear chain or nuclear bag?? And in what ration
nuclear chain fibers are more plentiful than nuclear bag fibers.
6:2
Compare nuclear bag and chain fibers in terms of:
Size
Arrangement of nucleus
Bag is bigger and its nucleus accumulated in a central region
Chain is smaller and its nucleus is arranged in rows
Sensory innervation of the muscle spindle consists of Ia afferent nerve, which innervates the—— region of———— fibers, and group II afferent nerves, which primarily innervate the ———fibers.
central
both the nuclear bag fibers and the nuclear chain
nuclear chain
Motor innervation of the muscle spindle consists of two types of γ motoneurons:——- and——-.
dynamic
static
Dynamic γ motoneurons synapse on —— fibers in “—— endings.”
Static γ motoneurons synapse on—— fibers in “——-endings,”
nuclear bag; plate
nuclear chain; trail
——- gamma motoneurons synapse in endings that go longer distances
Static
Which motor neuron is smaller and which is faster between gamma and alpha
Gamma is smaller and slower
The group Ia afferent fibers in a spindle detects the —— of length change, and the group II afferent fibers detect the ____ of the muscle fiber
velocity
length
The extrapyramidal rubrospinal tract originates in the ———and projects to motoneurons in the—— spinal cord. Stimulation of the ——produces activation of—— muscles and inhibition of——- muscles.
red nucleus
lateral
red nucleus
flexor; extensor
The pontine reticulospinal tract originates in ——-and projects to the——- spinal cord. Stimulation has a generalized——- effect on ———muscles
nuclei of the pons ; ventromedial
activating
both flexor and extensor
The pontine reticulospinal tract
Has its predominant effect on ——- muscles .
extensors
The medullary reticulospinal tract originates in the—— and projects to motoneurons in the spinal cord. Stimulation has a generalized——- effect on ——-muscles
medullary reticular formation
inhibitory
both flexor and extensor
The medullary reticulospinal tract
Has a predominant effect on —— muscles .
extensors
The lateral vestibulospinal tract originates in the——-and projects to —-lateral motoneurons in the spinal cord. Stimulation produces activation of——- and inhibition of——-.
lateral vestibular nucleus
ipsi
extensors
flexors
lateral vestibular nucleus
Is also know as the ———-nucleus
Deiters
The tectospinal tract originates in the——- and projects to the—— spinal cord. It is involved in control of—— muscles
superior colliculus
cervical
neck
The red nucleus is located in the——- ——- half of the———, dorsal to the——— complex
ventral; medial
midbrain tegmentum
substantia nigra
Lesions above the midbrain cause decerebrate rigidity.
T/F
F
lesions of the brain stem above the pontine reticular formation and lateral vestibular nucleus, but below the midbrain, cause a dramatic —— in extensor tone, called ——— rigidity.
increase
decerebrate
The cerebellum aka ——-
little brain
—— part of the brain controls synergy
Cerebellum
synergy is the ———-
rate, range, force, and direction of movements
Damage to the cerebellum results in lack of coordination.
T/F
T
The cerebellum is located in the—— fossa just below the—— lobe. It is connected to the brain stem by———-
posterior
occipital
three cerebellar peduncles
cerebellar peduncles contain only afferent nerve fibers.
T/F
F
They contain both afferent and Efferent
There are three main divisions of the cerebellum: the ——-cerebellum, the ——cerebellum, and the ——-cerebellum.
vestibulo
spino
ponto
The vestibulocerebellum is dominated by—— input and controls—— and—— movements.
The spinocerebellum is dominated by—— input and controls—— of movement.
The pontocerebellum is dominated by—— input, via—— nuclei, and controls ———and—— of movements.
vestibular; balance; eye
spinal cord; synergy
cerebral; pontine; the planning ; initiation
The cerebellar cortex has—— layers
While the cerebral cortex has —— layers
three
Six
Cerebellar output cells are the—— cells
Purkinje
List the layers of the cerebellar cortex saying which is innermost, middle, and outermost
Granular innermost
Purkinje middle
Molecular outermost
Of the cerebellum
The granular layer contains—— cells,—— cells, and———.
The Purkinje cell layer contains—— cells
The molecular layer contains ——-cells,—— cells,—— of Purkinje and Golgi II cells, and—— of granule cells.
granule; Golgi II; glomeruli
Purkinje
outer stellate ; basket
dendrites; axons
In the glomeruli, axons of—— fibers from the ——cerebellar and ——cerebellar tracts synapse on ——- of granule and Golgi type II cells.
mossy
spino; ponto
dendrites
output of the purkinje cerebellar cells are always inhibitory or excitatory???
Inhibitory
Two systems provide excitatory input to the cerebellar cortex: the—- fiber system and the—— fiber system. Each system also sends collateral branches directly to——-, in addition to their projections to the cerebellar cortex. Excitatory projections from the cerebellar cortex then activate secondary circuits, which modulate the output of the——- via the——— cells.
climbing; mossy
deep cerebellar nuclei
cerebellar nuclei
Purkinje
- Climbing fibers originate in the ——of the——- and project directly onto —— cells.
- These synaptic connections are powerful! A single action potential from a climbing fiber can elicit multiple excitatory bursts, called ——-.
inferior olive ; medulla; Purkinje
complex spikes
Climbing fibers make multiple synaptic connections along the dendrites of Purkinje cells
T/F
T
each Purkinje cell receives input from one or more climbing f iber.
T/F
F. Just one
climbing fibers “condition” the Purkinje cells
T/F
T
Climbing fibers modulate purkinje cells’ responses to ———input.
mossy f iber
Climbing fibers also may play a role in cerebellar learning.
T/F
T
——-fibers constitute the majority of the cerebellar input.
Mossy
Mossy fibers system includes——-,——-, and——- afferents.
vestibulocerebellar
spinocerebellar
pontocerebellar
Mossy fibers project to——- cells, which are—— interneurons located in collections of synapses called——.
granule
excitatory
glomeruli
Axons from these granule cells then——- to the——- layer, where they——- and give rise to——— fibers.
ascend
molecular
bifurcate
parallel
Parallel fibers from the granule cells contact the—— of many—— cells, producing a “beam” of—— along the row of Purkinje cells.
dendrites
Purkinje
excitation
Purkinje cell may receive input from as many as 250,000 parallel fibers
T/F
T
Mossy fibers produce —— spikes
Climbing fibers produce ——- spikes
Simple
Complex
With the exception of—- cells, all of the cerebellar interneurons are———.
granule
inhibitory
Say if the following inhibit or excite the purkinje cells
Granule cells
Basket cells
stellate cells
Excite
Inhibit
Inhibit
Effect of granule cells on stellate, golgi 2, and basket cells
Excites them
——-cells inhibit granule cells, thereby——- their excitatory effect on Purkinje cells.
Golgi II
reducing
Basket cells and stellate cells inhibit Purkinje cells via——- fibers
parallel
NT released at axon terminal of purkinje cells is ——-
GABA
Cerebellar lesions result in an abnormality of movement called ——-. This is a lack of ——— and can be exhibited in one of several ways. There may be a ——- of movement or ———of a movement, causing the movement to appear uncoordinated.
ataxia
Synergy
delayed onset
poor execution of the sequence
Ataxia may be expressed as dysdiadochokinesia, in which a person is unable to————
perform rapid, alternating movements
Intention tremors may occur perpendicular to the————, increasing near the———
direction of a voluntary movement
end of the movement.
Intention tremors seen in cerebellar disease = resting tremors seen in Parkinson disease.
T/F
F. They are different
The rebound phenomenon is the——— a movement; for example, if a person with cerebellar disease f lexes his forearm against a resistance, he may be unable to————
inability to stop
stop the flexion when the resistance is removed.
The supplementary motor cortex programs ——— motor sequences
complex
——- motor cortex is active during “mental rehearsal” of a movement, even in the absence of movement.
Supplemental motor cortex
motor homunculus is dramatically illustrated in——- seizures, which are epileptic events originating in the ———cortex. The epileptic event usually begins in the———, progresses to the———, and eventually spreads ——-(i.e., the “————-”).
jacksonian
primary motor
fingers of one hand
hand and arms
over the entire body
jacksonian march
