Neurophysiology 5: Motor System (Lecture 79)

Question 1

What is the function of the cerebellum?

Answer 1

Coordinates timing and smooth movements

DOES NOT INITIATE MOVEMENT (instead it corrects errors)

Question 2

The cerebellum in conjunction with the vestibular system helps maintain ______ _____. It also helps regulate muscle ________.

Answer 2

Vestibular system
Tone

Question 3

What is the importance of cerebellar peduncles?

Answer 3

Path for cerebellar efferents and afferent

Question 4

Cerebellar afferents coming from the spinal cord are what pathways/which info?

Answer 4

Spinocerebellar and spinocuneocerebellar pathways
Proprioceptive information and LMN

Question 5

Cerebellar afferents coming from the cerebral cortex are what pathways/which info?

Answer 5

Corticopontocerebellar pathway
Motor plan

Question 6

Cerebellar afferents coming from the brain stem are what pathways/which info?

Answer 6

Extrapyramidal action, eyes, ears
Brainstem UMN, tectum and vestibular nuclei

Question 7

What is the function of the spinocerebellum? Where does it send info to?

Answer 7

Coordinated movement and posture
Sends info to brainstem UMN

Question 8

What is the function of the pontocerebellum? Where does it send info?

Answer 8

Coordinated and properly timed skilled movement (limbs)
To motor cortex

Question 9

What is the function of vestibulocerebellum? Where does it send info?

Answer 9

Coordinated balance and eye movement
To vestibular nuclei

Question 10

Where are cerebellar efferents?

Answer 10

Deep cerebellar nuclei

Question 11

Cerebellar efferents do NOT have _____ ______ path. Meaning it is unable to initiate ______ or directly impact muscle ______.

Answer 11

Descending spinal path

Movement

Strength

Question 12

What is hypermetria?

Answer 12

Toy soldier walk

Question 13

What is ataxia?

Answer 13

Spinal walk

Question 14

What are signs of cerebellar dysfunction in spinocerebellar?

Answer 14

Hypermetria and ataxia

Question 15

What are signs of cerebellar dysfunction in pontocerebellar?

Answer 15

Intention tremors

Question 16

What are signs of cerebellar dysfunction in vestibulocerebellar?

Answer 16

Wide based stance

Question 17

Where is the vestibular apparatus? What is the function? What receptor does it house?

Answer 17

Located in the inner ear

Sets body equilibrium or balance

Houses the receptor organs for detecting head position and movement

Question 18

The vestibular apparatus stabilizes what and coordinates what?

Answer 18

Stabilizes position of the head and trunk

Coordinates eye movements

Question 19

Where are the receptors found in the vestibular apparatus?

Answer 19

Three semicircular ducts
Vestibule

Question 20

Which receptor if found in the three semicircular ducts? What does it sense?

Answer 20

Crista apmullaris

Sense angular acceleration

Question 21

What are the receptors found in the vestibule? What do they sense?

Answer 21

Macula saccule and macula utricle

Sense static equilibrium/balance and linear acceleration

Question 22

What is the 1st order neuron in the vestibular apparatus? What is the 2nd order neuron?

Answer 22

1st : vestibulocochlear nerve and vestibular ganglion
2nd: vestibular nuclei in medulla

Question 23

Describe the structure of crista ampullaris

Answer 23

Bathed in endolymph (high in K)
Hair cells embedded in gelatinous cupola
Lag behind endolymph during movement
Sterocilia tip toward kinocilium to induce AP

Question 24

How does the crista ampullaris induce AP

Answer 24

Stereocilia tip toward kinocilium to induce AP

Question 25

Describe the structure of the macula saccule and macula utricle

Answer 25

Hair cells imbedded in gelatinous layer with otholiths
Otholiths (ear rocks) weigh down membrane and stimulate hair cells

Question 26

What are the vestibular nuclei projections?

Answer 26

Vestibulospinal tract
Medial longitudinal fasciculus
Cerebellum
Emetic Center

Question 27

How does the vestibulospinal tract function?

Answer 27

Ipsilateral ventral funiculus
Activates extensor and inhibits flexors

Question 28

Where does the medial longitudinal fasciculus go to? What is the function?

Answer 28

Goes to CNS III IV VI which innervate extraocular muscles

Helps eye fix on target- ‘Gazes stabilization’

Question 29

What are the two pathways from vestibular system to cerebellum?

Answer 29

Direct: primary vestibular axons to cerebellar flocculonodular lobe
Indirect: vestibular nuclei project to cerebellar flocculonodular lobe

Question 30

What is the peripheral vestibular subdivision?

Answer 30

Receptors (hair cells), vestibular nerve (inner ear structure)

Question 31

What is the central vestibular subdivision?

Answer 31

Brain stem and cerebellar vestibular structure

Question 32

Classic sign of vestibular disease? Which side is the lesion on?

Answer 32

Head tilt

Head tilt is towards lesion (because ipsilateral effect)

Question 33

Signs of vestibular disease

Answer 33

Nystagmus
Head Tilt
Leaning/Falling/

Question 34

How can you decide which side the vestibular system is damaged on, just based on nystagmus?

Answer 34

Vestibular system damaged on slower side of eye movement

Question 35

Describe cerebellar ataxia?

Answer 35

Not knowing where you are in space, exaggerated movements, wide base stance

Question 36

Describe vestibular ataxia

Answer 36

Head tilt with ataxia, horizontal eye movements, balance issues, falling to one side

Question 37

Describe spinal/ proprioceptive ataxia

Answer 37

Crossing over, feet tangled up, thoracic/pelvic limb moving at different paces