2-4 sensorimotor system

Question 1

what type of arrangement does the sensorimotor system have

Answer 1

somatotopic

Question 2

sensory info is processed by what 2 main pathways

Answer 2

pain & temp

touch & position

Question 3

motor info is mediated by what 2 main pathways

Answer 3

corticospinal tracts go to the body

corticobulbar tracts go to the head & neck

Question 4

what is the final common pathway to the muscle

Answer 4

the lower motorneuron

Question 5

the cranial nerves control muscles that are important for what

Answer 5

voice & speech

Question 6

where do motorneurons have their nuclei

Answer 6

anterior horn

Question 7

where do sensory neurons have their nuclei

Answer 7

posterior horn

Question 8

dorsal root ganglion

Answer 8

before the dorsal root fibers join the spinal column

contains sensory nerve bodies

Question 9

dorsal root

Answer 9

consists of the fibers that transmit impulses to the CNS

afferent

Question 10

dorsal columns pathway

Answer 10

come into spinal cord on ipsilateral side & travels up to medulla

2nd order neuron cross in medulla then onto thalamus
- becomes medial lemniscus

thalamus projects to primary sensory areas

Question 11

dorsal columns sensory info

Answer 11

ascending tracts w/ info about touch & limb position

lesions cause ipsilateral damage

Question 12

spinothalamic tract pathway

Answer 12

immediately crosses over at spinal cord

2nd axon travels to thalamus

Question 13

spinothalamic tract sensory info

Answer 13

carries pain & temp info

lession will causes contralateral pain & temp deficits

Question 14

innervation ratio

Answer 14

the number of fibers controlled by 1 neuron

Question 15

low innervation ratio =

Answer 15

very fine motion

Question 16

large innervation ratio =

Answer 16

large force & motion

Question 17

how is a muscle action potential generated

Answer 17

acetylcholine opens gates allowing Ca2+ ions in

this release causes small filaments within muscle fiber to shorten – muscle contraction

Question 18

myasthenia gravis

Answer 18

chronic autoimmune disorder

weakness of skeletal muscles

reduced efficiency in muscle contraction, they cannot contract repeatedly

eye fatigue

Question 19

MG cause

Answer 19

dysfunction at the neuromuscular junction

decrease in the ability of Ach to act as a neurotransmitter

receptor sites for Ach do not function

Question 20

reflex

Answer 20

involuntary - in response to sensory stimulation

simple stretch reflex - sensory neuron –> motor neuron

pain reflex - pain neuron –> interneuron –> motor neuron

Question 21

central pattern generator

Answer 21

network of neurons capable of carrying out patterned motor response

more complex than a reflex

voluntary but don’t really have to think about it

Question 22

volitional movement

Answer 22

organized around the performance of a purposeful task

improves w/ experience/practice

Question 23

lower motor neuron

Answer 23

lesion at a brainstem spinal motor nucleus or in the nerves leading out to the muscles

Question 24

composition of LMN

Answer 24

cell body - brainstem or spinal cord

axon

motor end plate - synapse onto muscle

controls ipsilateral muscles

Question 25

LMN integration

Answer 25

peripheral sensory system - reflexes, ongoing modulation

direct activation system - UMN / cortical system activates LMN, volitional movement

indirect activation system - extrapyramidal influences LMN

Question 26

damage to LMN

Answer 26

weakness

paralysis if muscles if deprives of all input

hyporeflexia - reflexes are diminished

atrophy

fasiculation - spontaneous motor unit discharges that can be seen as twitches

fibrillation - muscles contract regularly, can’t be seen through skin

Question 27

upper motor neuron

Answer 27

neurons that form the descending motor pathways from the brain to the spinal cord or brainstem

corticobulbar & corticospinal fibers (pyramidal tracts)

Question 28

effects of damage from UMN

Answer 28

weakness (spastic – tight & stiff)

increased background muscle activity – additional firing

lack of muscle control

hyper-reflexia

Question 29

corticobulbar tract

Answer 29

fibers originate from the cerebral cortex & descend

fibers branch off at the medulla, pons, & midbrain

cross over at the brainstem at the level of thee CN nuclei they innervate

most bilateral, some unilateral

Question 30

direct activation pathways

Answer 30

UMN inervates LMN bilaterally or contralaterally

Question 31

pyramidal tract

Answer 31

direct

originated form primary motor area & descends through internal capsule

cortiobulbar or corticospinal tracts

Question 32

damage to direct activation pathways

Answer 32

loss or reduction of skilled movements

Question 33

indirect pathways

Answer 33

descending projections from cortex (BG) to gamma motor neurons

reticular formation of pons & medulla that project to spinal cord (reticulospinal tract)

Question 34

gamma motorneurons

Answer 34

set the background muscle activity & excitability

Question 35

indirect pathways functions

Answer 35

reflexes

posture

background muscle activity

skilled, discrete actions

Question 36

extrapyramidal system

Answer 36

complex

functions for speech & swallowing

UMN

influenced by BG, cerebellum, sensory cortical areas, vestibular nuceli

Question 37

tectospinal tract

Answer 37

extrapyramidal

regulates neck & body twisting movements w/ support from visual & auditory startle reflexes

Question 38

rubrospinal tract

Answer 38

regulates muscle tone for limb extension to support body against gravity

Question 39

vestibulospinal tract

Answer 39

regulates reflexive adjustment of the body & limbs to keep the head stable

Question 40

how does primary motor cortex contribute to movement

Answer 40

motor commands for execution of movement

only cortical area w/ a direct projection to corticospinal tract

Question 41

how does premotor cortecx contribute to movement

Answer 41

plans skilled movements w/ external targets

projects to primary motor cortex & extrapyramidal brainstem

Question 42

how does supplemental motor cortex contribute to movement

Answer 42

plans sequences of actions

Question 43

basal ganglia functions

Answer 43

regulates background muscle activity

supports goal directed movements

postural adjustments during skilled movements

learning new movements

initiates movements

Question 44

BG input

Answer 44

cortical from areas involved in planning & execution of movements

Question 45

BG output

Answer 45

via thalamus to the motor cortical areas

Question 46

BG controls

Answer 46

contralateral

Question 47

BG input structures

Answer 47

striatum

caudate
putamen

Question 48

BG output structures

Answer 48

globus pallidus

internal & external segment

substantial nigra

Question 49

other BG structures

Answer 49

substania nigra
pars compacta (dopamine)
pars reticula

subthalamic nucleus

nucleus accumbens

Question 50

neurotransmitters in BG

Answer 50

dopamine – modulatory

acetylcholine – high concentrations

glutamate (excitatory)

GABA (inhibitoty)

Question 51

Parkinson’s Disease

Answer 51

rigidity

initiation difficulties

slowness

olfaction, cognition, autonomic, mood, sleep

Question 52

Parkinson’s treatments

Answer 52

drugs - levodopa, dopamine

behavioral - exercise

surgical - ablation, transplantation, deep brain stimulation

Question 53

how is huntington’s inherited

Answer 53

autosomal dominant genetic disorder

typically develops around 35-45 yrs

Question 54

huntington’s symptoms

Answer 54

chorea, jerky & involuntary movements

cognitive deficits

psychiatric disorders

Question 55

huntington’s treatment

Answer 55

tetrabenzine (VMAT inhibitor) & other drugs

functional therapy

Question 56

function of cerebellum

Answer 56

process info from all parts of the brain to produce coordinated, smooth movement

balance
hand-eye coordination

IPSILATERAL

Question 57

cerebellum input

Answer 57

from sensory systems & sensorimotor systems like cortex & BG

Question 58

cerebellum output

Answer 58

to the brainstem, extrapyramidal system, & cerebral motor cortices

Question 59

4 main pathways of cerebellum

Answer 59

cerebrocerebellar

spinocerebellar

vestibuloscerebellar

pontocerebellar