Neuro Final 2

Front 1

a lesion in the contralateral corticospinal tract below the pyramidal decussation results in what?

Back 1

ipsilateral motor loss of what is innvervated because the fibers have crossed => ipsilateral spastic pearesis and Babinski's sign

Front 2

a lesion in the contralateral corticospinal tract above the pyramidal decussation results in what?

Back 2

contralateral motor loss of the entire side because the fibers have not crossed => contralateral spastic paresis and Babinski's sign

Front 3

The pyramidal tracts synapse on what?

Back 3

directly onto visceral motor neurons; most synapse on intermediate neurons and not directly on the alpha motor neurons to act as inhibitor

Front 4

Which part of the brain is the main sensory receptor area?

Back 4

the thalamus

Front 5

which area of the brain serve as the motor discharge areas?

Back 5

basal ganglia and subthalamic nuclei

Front 6

What type of movements does the cerebral cortex start?

Back 6

complicated voluntary movements

Front 7

What part of the brain is in chrage of equilibrium?

Back 7

flocculonodular lobe of the cerebellum

Front 8

Why is the pyramidal system clinically important?

Back 8

strokes often affect the motor system so it is critical to understand its pathway

Front 9

What layer is most distinct in the postcentral gyrus?

Back 9

layer IV, which generally receives sensory information

Front 10

What layer is most distinct in the precentral gyrus?

Back 10

layer V, which is responsible for sending information down the brainstem and beyond

Front 11

Where does the corticospinal tract originate?

Back 11

axons of the pyramidal neurons in layer V of the primary motor cortex

Front 12

Are Betz cells the sole source of the corticospinal tract?

Back 12

nope! they're only a subset of pyramidal neurons that make up the tract

Front 13

Through what part of the internal capsule do the motor and somatosensory information travel?

Back 13

posterior limb of the internal capsule

Front 14

Stroke of which arteries can affect the internal capsule?

Back 14

lenticulostriate and middle cerebral

Front 15

What do the cerebral peduncles contain?

Back 15

make up the floor of the midbrain and contain all the descending axons going to the brainstem or spine

Front 16

What happens to the pyramidal tract when it gets to the pons?

Back 16

axons from the corticopontine tract get off and synapse and the remaining corticospinal axons get a little fragmented and are no longer seen as a nice tight bundle

Front 17

What are the pyramids of the medulla?

Back 17

run the entire length of the medulla; are large uninterupted axon tracts on the ventral surface of the medulla

Front 18

Which system has a better ability to synapse on the alpha motor neuron?

Back 18

the pyramidal tract

Front 19

What is the anterior corticospinal tract?

Back 19

fibers that did not cross at the pyramidal decussation. these fibers sit ventrally, on either side of the midline in the spinal cord

Front 20

Fine finger movements and tap dancing are exclusive domain to which tract?

Back 20

lateral corticospinal tract

Front 21

Which muscles does the anterior corticospinal tract innervate?

Back 21

muscles of the trunk

Front 22

What controls the girdle muscles?

Back 22

both the anterior and lateral corticospinal tracts

Front 23

The red nucleus receives ipsilateral topographical input from the motor cortex and functions as what?

Back 23

indirect corticospinal tract

Front 24

Where do axons of the rubrospinal tract cross?

Back 24

in the ventral tegmental decussation and descend in the lateral brain stem and lateral funiculus of the spinal cord (where they can intermix w/ the lateral corticospinal tract)

Front 25

Where does the rubrospinal tract terminate?

Back 25

directly or indirectly on the alpha LMN and gamma LMN in the spinal cord associated with it

Front 26

What type of movements are involved with the rubrospinal tract?

Back 26

flexor movements of the lower extremity

Front 27

Why does extensor spasticity occur with RST and CST lesions?

Back 27

the flexor system becomes inhibited so the extensor system acts unopposed

Front 28

Describe the pathway of the lateral vestibulospinal tract.

Back 28

originates from lateral vestibular nucleus and terminates directly or indirectly on the ipsilateral alpha LNM and ipsilateral gamma LMN associated with the extensor musculature, (especially proximal)

Front 29

What type of system is the lateral vestibulospinal tract?

Back 29

powerful antigravity extensor system => kept in check by rubrospinal tract and cerebellum => destruction of red nucleus or cerebellum leads to extensor hypertonia

Front 30

Describe the pathway of the medial vestibulospinal tract.

Back 30

arises from teh medial vestibular nucleus and provides inhibition of the alpha and gamma motor neurons that control the neck and axial musculature. they terminated on interneurons in the cervical spinal cord ventral horn

Front 31

Describe the pathway of the reticulospinal tract.

Back 31

arises from reticular formation, travels ipsilaterally, and terminates directly and indirectly on alpha and gamma motor neurons

Front 32

What is the medial reticulospinal tract involved with?

Back 32

distinct extensor bias with axial muscles and reinforces the action of the lateral vestibulospinal tract

Front 33

What drives the medial reticulospinal tract?

Back 33

poly sensory input from the trigeminal and somtosensory sources

Front 34

What is the medullary (lateral) reticulospinal tract?

Back 34

originates from the medial reticular formation and is driven by the cortical inpul, especially from the motor and premotor areas; terminates bilaterally directly and indirectly on the alpha and gamma motor neurons

Front 35

Describe the path of tectospinal tract.

Back 35

arises from the superior colliculus, decussates in the dorsal tegmental decussation, descendds contralaterally near the midline and terminates directly and indirectly on the alpha and gamma motor neurons

Front 36

Describe the path of the interstitiospinal tract.

Back 36

arises from the interstitial nucleus of Cajal and helps coordinate eye movements and gaze, it descends ipsilaterally in the MLF and terminates directly and indirectly on alpha and gamma motor neurons associated with axial musculature and trunk movements

Front 37

What is a Babinski sign?

Back 37

upper motor neuron lesion, clonus type syndrome; fanning out of toes when plantar surface of foot is stroked upwards

Front 38

What are the connections of the cerebellum?

Back 38

inferior cerebellar peduncle (contains spinocerebellum fibers); middle cerebellar peduncles (contains transverse pontine or pontocerebellar fibers); superior cerebellar peduncles (fibers from cerebellum to pons)

Front 39

What are some symptoms of cerebellar lesions?

Back 39

intention tremor, dysarthira, nystagmus, cerebellar ataxia

Front 40

What is Charcot's triad?

Back 40

nystagmus, dysarthria, and intention tremor

Front 41

Charcot's triad is associated with what?

Back 41

multiple sclerosis

Front 42

Unilateral lesions of the cerebellum cause symptoms on which side of the body?

Back 42

the same side

Front 43

Midline lesions of the cerebellum result in what?

Back 43

loss of postural control, making it impossible to stand or sit without topping over

Front 44

unilateral cerebellar hemispheric lesions cause what?

Back 44

ipsilateral loss of coordination of the arm (intention tremor) and of leg resulting in unsteady gait in the absence of weakness or sensory loss

Front 45

What is the difference between a cerebral and cerebellar lesion?

Back 45

cerebral lesion results in loss of motor or sensory while cerebellar lesion results in loss of fine movement

Front 46

What results from bilateral dysfunction of the cerebellum?

Back 46

dysarthria and cerebellar ataxia

Front 47

What are some key features of the cerebellum?

Back 47

largest part of hindbrain, originates from the dorsal aspect of the brain stem and overlies the fourth ventricle

Front 48

What does the cerebellum control?

Back 48

maintenance of equilibrium (balance), influences posture and muscle tone, coordinates movement

Front 49

What type of function does the cerebellum perform?

Back 49

entirely motor and operates on an unconscious level

Front 50

Where does the superior surface of the cerebellum lie?

Back 50

beneath the tnetorium cerebelli with the superior vermis raised forming a midline ridge

Front 51

Where does the inferior vermis of the cerebellum lie?

Back 51

in a deep groove between the hemispheres just underneath the nodule

Front 52

What does the primary fissure separate?

Back 52

anterior from the posterior lobe

Front 53

What does the posterior-lateral fissure demarcate?

Back 53

the location of the flocculonodular lobe

Front 54

Is the vermis a lobe?

Back 54

nah, son! it's a connection area between 2 sides

Front 55

Can you control or override the cerebellum?

Back 55

nope! it's unconscious

Front 56

What are the 2 components of the cerebellum?

Back 56

cerebellar cortex (outer layer of gray matter) and the inner core of white matter

Front 57

what consistutes the inner core of white matter of the cerebellum?

Back 57

largely afferent and efferent fibers that run to and from the cerebellum and 4 pairs of cerebellar nuclei that have important connections with the cerebellar cortex and certain nuclei of the brainstem and thalamus

Front 58

which is the only nucleus that can be seen without a microscope and with proper staining?

Back 58

dentate nucleus

Front 59

What are the 3 layers of the cerebellar cortex?

Back 59

molecular layer (outer, fiber rich); Purkinje layer(tight, narrow, well-defined); inner granular layer (dominated by granule cells)

Front 60

Are the granular cells in the cerebellum and cerebrum the same?

Back 60

no

Front 61

From where do the afferents to the cerebellum arise?

Back 61

spinocerebellar (spinal cord); olivocerebellar (inferior olivary sulcus); vestilocerebellar (vestibular nuclei); pontocerebellar/transverse pontine fibers (pons)

Front 62

What are mossy fibers?

Back 62

all afferents to the cerebellum except for the inferior olivary nucleus

Front 63

What is the path of the mossy fibers?

Back 63

supply several folia and end in the granule layer in synaptic contact with granule cells; axons then pass towards the aruface of the cortex and enter the molecular layer where they bifurcate to produce 2 parallel fibers that are oriented along the long axis of the folium; fibers synapse on the dendrites of Purkinje cells

Front 64

Describe the purkinje cell layer.

Back 64

consists of a unicellular layer of somata of Purkinje neuronsl with profuse dendritic arborizations that extend towards the surface of the cortex into the molecular layer

Front 65

Which axons are the only ones to leave the cerebellar cortex?

Back 65

axons of Purkinje layer, though a majority don't leave and end up in the deep cerebellar nuclei

Front 66

What are the output cells of the cerebellum?

Back 66

Purkinje cells; dendrites of purkinje cells go up and make connections w/ climbing and mossy fibers. information is processed in the cell body and output goes to nuclei

Front 67

What neurotransmitter do the Purkinje cells use, and what does this imply?

Back 67

GABA is an inhibitory NT, meaning that the output of almost all the cerebellar cortex is mediated through inhibtion cells in the cerebellar nuclei

Front 68

What are climbing fibers of the cerebellum?

Back 68

originate from the inferior olivary nucleus and provide excitatory input to the Purkinje cells

Front 69

Do climbing fibers excite or inhibit cerebellar nuclei?

Back 69

both! climbing fibers excite Purkinje cells, which inhibit cerebellar nuclei (indirect inhibition) and collaterals of climbing fibers excite the neurons of the deep cerebellar nuclei (direct excitation)

Front 70

What are the cerebellar nuclei, and where are they located?

Back 70

The nuclei are within the white matter above the roof of the forth ventricle: fastigial, globose, emboliform, dentate

Front 71

Where does the dentate nucleus receive its afferent input?

Back 71

inferior olivary nucleus => Purkinje cells and climbing fibers

Front 72

What constitutes the primary source of efferent fibers from the cerebellum to other parts of the brain?

Back 72

cerebellar nuclei =>the principle destination of these efferent fibers are reticular and vestibular nuclei of the medulla and pons, red nucleus of the midbrain, ventral lateral nucleus of the thalamus

Front 73

What are the 3 functional subdivisions of the cerebeluum?

Back 73

archicerebellum, paleocerebellum, neocerebellum

Front 74

What is the archicerebellum equated with and what is its function?

Back 74

equated with the flocculonodular lobe and associated with the fastigial nucleus; concerned with the maintenance of equilibrium

Front 75

The archicerebellum has extenisive connections with what nuclei?

Back 75

vestibular and reticular nuclei of the brainstem through the ingerior cerebellar peduncles (becomes intermixed w/ spinocerebellar fibers, which come up)

Front 76

Is the influence of the archicerebellum on the lower motor system bilateral?

Back 76

yerpz, it's principally mediated by means of descending vestibulospinal and reticulospinal projections.

Front 77

Is the archicerebellum ipsilateral?

Back 77

yessir, it's associated with Purkinje fibers, too.

Front 78

what does the paleocerebellum influence?

Back 78

muscle tone and posture

Front 79

Where do afferents of the paleocerebellum come from?

Back 79

dorsal and ventral spinocerebellar tract neurons that carry information from muscle, joint, and cutaneous receptors => enter cerebellum through the inferior (dorsal) and superior (ventral) cerebellar peduncles

Front 80

Where do the afferent fibers that go to the paleocerebellum terminate?

Back 80

ipsilateral vermis and paravermis

Front 81

Where do the cerebellar cortical efferents of the paleocerebellum go?

Back 81

globose and emboliform nucle and fastigial nucleus; globose and emboliform nuclei project via superior cerebellar peduncles to contralateral red nucleus where they influence the rubrospinal tract; after these fibers synapse on the red nucleus they cross back and go down ipsilaterally

Front 82

What is the neocerebellum concerned with?

Back 82

muscular coordination, including trajectory, speed, and force of movements; done primarily through action on cerebral cortical areas that give rise to descending corticospinal and corticobulbar pathways

Front 83

What are the principle afferents of the neocerebellum

Back 83

pontocerebellar fibers that originate in the pons, cross to the opposite side, and enter the cerebellum through the middle cerebellar peduncles

Front 84

Where is the output of the neocerebellum directed to?

Back 84

dentate nucleus, which in turn projects to the contralateral red nucleus and ventral lateral nucleus of the thalamus

Front 85

How does the archicerebellum and vestibular nuclei affect the vestibulospinal tract?

Back 85

vestibular nuclei sends info via mossy fibers to granule cells/fibers. granule fibers synapse on Purkinje fibers, which go down to synapse on the fastigial nucleus, goes back to vestibular nucleus and affects the vestibulospinal tract

Front 86

Where do most of the fibers from the dentate nucleus go?

Back 86

most bypass the red nucleus and pass directly to the ventral lateral thalamus, which projects to the cerebral cortex

Front 87

the neocerebellum corresponds to what part of the cerebellum?

Back 87

cerebellar hemisphere

Front 88

What is the basal ganglia?

Back 88

several cell groups embedded in cerebral hemispheres

Front 89

What are the functions of the basal ganglia?

Back 89

can modify and integrate info. coming from cortex and relay it to important thalamic nuclei, which can feedback to the cortex; can project to other areas of the brainstem and indirectly affect motor by indirect stimulation of motor neurons in spinal cord

Front 90

What is the role of the striatal motor system (extrapyramidal motor system)?

Back 90

palys a role in initiation and execution of somatic motor activity and is involved with automatic, stereotyped motor activity (postural activity)

Front 91

what does the dorsal division of the basal ganglia consist of?

Back 91

neostriatum (caudate and putamen); paleostriatum (globus pallidus); functionally: substantia nigra, subthalamic nucleus, parabrachial pontine reticular formation

Front 92

What constitues the ventral division of the basal gnaglia?

Back 92

substantia innominata, nucleus basalis of Meynert, nucleus accumbens, and olfactory tubercle; associated with portions of the amygdala and ventral tegmental area

Front 93

What are the 2 complexes of the basal ganglia?

Back 93

striatal and pallidal

Front 94

what are the divisions of the striatal complex?

Back 94

neostriatum (caudate and putamen) and ventral striatum (nucleus accumbens and olfactory tubercle)

Front 95

What are the divisions of the pallidal complex?

Back 95

globus pallidus and ventral pallidum/substantia innominata

Front 96

What are strisomes?

Back 96

patches in the striatal complex that are most prominent in the head of the caudate; they are poor in acetylcholinesterase and have neuropeptide and opiate receptors

Front 97

The matrix of the striatal complex has a high concentration of what?

Back 97

acetylcholinesterase

Front 98

do neurons within the patches and matrix ever cross?

Back 98

nope

Front 99

what are the primary cell type throughout the striatum?

Back 99

medium spiny neurons, which use GABA and neuropeptides as NT, meaning that the connection is inhibitory and neuromodulatory

Front 100

What type of axons do medium spiny neurons have?

Back 100

striatopallidal fibers (projections into pallidal complex)

Front 101

What are the afferents of the neostriatum?

Back 101

mainly corticostraiate from all regions of the cortex that travel via the internal and external capsule; the fibers from the somatomotor cortex project primarily between the putamen and the caudate nucleus receives afferents from the association areas

Front 102

What is the head of the caudate nucleus involved in?

Back 102

cognitive function b/c it receives heavy projectinos from the prefrontal cortex

Front 103

What are nigrostriatal afferents?

Back 103

originates from the pars compacta, is a very organized projection, and releases dopamine on its target.

Front 104

destruction of what system results in Parkinson's disease?

Back 104

nigrostriatal afferents

Front 105

What are the thalamostriate afferents?

Back 105

arise from the intralaminar nuclei of the thalamus (centromedian) with collaterals that go to the cerebral cortex and have an unknown function

Front 106

What are the 2 divisions of the paleostriatum (globus pallidus)?

Back 106

medial division (medial segment of GP) and lateral division (lateral segment of GP and ventral pallidum)

Front 107

How are the two division sof the paleostriatum connected?

Back 107

reciprocally through pallidopallidal fibers

Front 108

What type of neurons are present in the paleostriatum?

Back 108

GABAnergic neurons w/ spontaneous activity; these neurons are tonically active and, therefore, always exerting some kind of inhibitory control over the target

Front 109

The medial segment of GP subserves what?

Back 109

direct basal nuclear pathway

Front 110

What are the afferents of the medial segment of GP?

Back 110

striatal complex (GABA and substance P)

Front 111

What are the efferents of the medial segment of the GP?

Back 111

ansa lenticularis and lenticular fasciculus (both go to the thalamus); join the thalamic fasciculus and terminate on VA, VL, and CM

Front 112

The lateral division of GP subserves what?

Back 112

indirect basal nuclear pathway

Front 113

What are the afferents of the lateral division of GP?

Back 113

striatal complex (major input) and subthalamic nucleus and substantia nigra

Front 114

What are the efferents of the lateral division of GP?

Back 114

projects strongly to subtalamic nucleus and substantia nigra

Front 115

From where does the subthalamic nucleus receive input?

Back 115

lateral pallidal, cortex, nigral complex, and parabrachial pontine reticular formation

Front 116

Where does the subthalamic nucleus project to?

Back 116

pallidal divisions and substantia nigra

Front 117

what type of neurotransmitter does the subthalamic nucleus use?

Back 117

glutamate, but are mostly inhibited by external pallidal division => is tonically quiet

Front 118

What are the divisions of the substantia nigra?

Back 118

pars compacta and pars reticulata

Front 119

what is the pars compacta?

Back 119

dopamine neurons with neuromelanin projecting mainly to neostriatum

Front 120

what is the pars reticulata?

Back 120

GABA neurons projecting to neostriatum, thalamus, superior colliculus, and parabrachial pontine reticular formation

Front 121

What is the ventral tegmental area?

Back 121

part of the nigral complex (with the substantia nigra) that has dopamine neurons projecting to ventral striatum, amygdala and other limbic structures

Front 122

What is the modulatory loops of the substantia nigra?

Back 122

pars compacta and reticulata are interconnected: dendrites from dopamine neurons in pars compacta extend into the pars reticulata and release free dopamine which modulates the resting potentiall the pars reticulata neurons project collateral into the compacta forming GABAergic synapses

Front 123

The modulatory loop of the substantia nigra is regulated by segregated output fro the striatum.

Back 123

striosome --> pars compacta; matrix --> pars reticulata

Front 124

What nucleus does the parabrachial pontine reticular formation contain?

Back 124

pedunculopontine tegmental nucleus (PPTN), which contains cholinergic, glutamatergic, and GABAergic cells and lies in the lateral tegmentum

Front 125

What are the connections of the PPTN and basal nuclei and associated nuclei?

Back 125

receives GABAergic input from GP; projects glutamatergic fibers to GP and subtantia nigra; cholinergic projections to substantia nigra pars compacta