Lecture 18 (Corticospinal)

Question 1

M1

Answer 1

Primary motor cortex

Question 2

CST

Answer 2

Corticospinal tract

Question 3

PMC

Answer 3

Premotor cortex

Question 4

SMA

Answer 4

Supplementary motor area

Question 5

BA

Answer 5

Brodman’s area

Question 6

MC

Answer 6

Motor cortex

Question 7

RF

Answer 7

Reticular formation

Question 8

SC

Answer 8

Spinal cord

Question 9

SS ctx

Answer 9

Somatosensory cortex

Question 10

m.

Answer 10

Muscle

Question 11

LCST

Answer 11

Lateral CST

Question 12

VCST

Answer 12

Ventral CST

Question 13

FF

Answer 13

Feedforward

Question 14

FB

Answer 14

Feedback

Question 15

p/w

Answer 15

Pathway

Question 16

Mvt

Answer 16

Movement

Question 17

M1 location

Answer 17

Precentral gyrus of the frontal lobe - BA4

Question 18

M1 cells

Answer 18

Pyramidal cells (layer V)

Question 19

M1 projections

Answer 19

Afferent projections from PMC & SMA
- predominantly ipsilateral
Afferents also from 1* sensory cortex
Basal nuclei & cerebellum function as “consultants”

Question 20

M1 functions

Answer 20

• Mvts coordinated by M1 & BA 6
• Simple muscle contraction combinations
• BA 6 helps combine those combinations into complex mvts

Question 21

Premotor Cortex

Answer 21

Somatotopic representation of complete body musculature

Question 22

PMC - input

Answer 22

Sensory areas of parietal cortex

Question 23

PMC - output

Answer 23

M1 & spinal cord

Question 24

PMC - function

Answer 24

Involved in control of proximal limb - used to position arm for movement tasks

Question 25

Supplementary Motor Area

Answer 25

Contains complete map of body musculature

Question 26

SMA - function

Answer 26

Planning & learning complex, internally generated movements - Blood flow increases even if movement is mentally rehearsed - Bilateral movements are produced

Question 27

SMA - input

Answer 27

Parietal lobe

Question 28

SMA - output

Answer 28

M1 & spinal cord

Question 29

Posterior Parietal Cortex

Answer 29

BA 5 & 7

Question 30

Posterior Parietal Cortex - function

Answer 30

Carries out background computation BA 5 - receives input from somatosensory & vestibular systems BA 7 - processes visual info related to location of objects in space

Question 31

Posterior Parietal Cortex - output

Answer 31

SMA & PMA - few BS & spinal cord projections

Question 32

Pyramidal system

Answer 32

Descending pathway from motor cortex - UMN and LMN - Corticospinal and corticonuclear tracts

Question 33

Functional divisions motor system

Answer 33

- direct activation p/w - indirect activation p/w - control circuits - final common p/w

Question 34

Corticospinal p/w

Answer 34

- Corticonuclear tracts - Lateral CS tracts - Anterior CS tracts

Question 35

Medial p/w

Answer 35

- Vestibulospinal tracts - Tectospinal tracts - Reticulospinal tracts

Question 36

Lateral p/w

Answer 36

- Rubrospinal tracts

Question 37

CST

Answer 37

Corticospinal Tract - Corona radiata - Internal capsule - Cerebral peduncle of the midbrain - Pontine nuclei - Decussation at the medulla - Uncrossed: anterior corticospinal tract (ACST) - Crossed: lateral corticospinal tract (LCST)

Question 38

LCST

Answer 38

- Terminates in ventral horn or intermediate gray matter - Topographically organized - Fractionation of movement - Influence exerted depend on # of synapses

Question 39

ACST

Answer 39

- Terminates on MN or interneurons in medial region of ventral horn or intermediate gray matter - Affects activity of MN for axial muscles

Question 40

How is voluntary movement accurate?

Answer 40

Tactile, visual, proprioceptive information

Question 41

Corticonuclear Tracts

Answer 41

- Bilateral projection: UMN descend bilaterally, majority fibers project to contralateral LMN - Except for to the facial motor nucleus

Question 42

Facial nucleus

Answer 42

Upper face: both crossed and uncrossed corticobulbar input Lower face: only crossed corticobulbar input

Question 43

Motor Cortex - nuclei

Answer 43

- Tectum: mainly contralateral, tectospinal - Red nucleus: mainly contralateral, rubrospinal - Reticular formation: bilateral projection, reticulospinal - Vestibular nuclei: mainly ipsilateral, vestibulospinal

Question 44

Positive vs. negative signs

Answer 44

negative: loss of capacity positive: abnormal, stereotyped responses

Question 45

UMN lesions

Answer 45

- spasticity - denervation atrophy, reduced muscle volume - distributed diffusely, large group of muscles

Question 46

LMN lesions

Answer 46

- no spasticity - affects muscles in achy way - may be limited to single muscles

Question 47

Pyramidal tract - damage (corticospinal)

Answer 47

- above decussation: contralateral paralysis - below decussation: ipsilateral paralysis

Question 48

Pyramidal tract - damage (corticonuclear)

Answer 48

- effects are less severe than effects of corticospinal lesions - symptoms vary depending on cranial nerve

Question 49

Rhythmic motor patterns

Answer 49

- chewing, swallowing, scratching, walking - circuits lie in spinal cord & brain stem - usually triggered by stimulus