Descending Systems

Question 0

recent tracks utilize

Answer 0

older systems, which have more general effects and often influence reflex responses

Question 1

3 functions of descending tracts

Answer 1

control motor neurons
other motor functions (autonomic)
modify sensory transmission

Question 2

older systems directed as

Answer 2

postures

tone and proximal limb or trunk motions

Question 3

lateral funiculus

Answer 3

distal extremities

Question 4

anterior funiculus

Answer 4

movement of trunk

Question 5

ventrolateral funiculus

Answer 5

interneuron pools to axial and proximal limb muscles-bilateral effect

Question 6

descending tracts taht run mostly in MLF and what do they effect

Answer 6

tectospinal, medial vestibulospinal, pontine reticulospinal

trunk/neck movement

Question 7

what do medial motor tracts have in common?

Answer 7

terminate bilaterally
axial muscle control (control of neck and trunk)
located in anterior funiculus

Question 8

located in the MLF

Answer 8

medial vestibulospinal

pontine reticulospinal

Question 9

located immediately adjacnet to MLF

Answer 9

tectospinal tract

Question 10

4 things all MLF tracts have in common

Answer 10

enter anterior funiculus of cord (part of medial motor system)
only affect axial muscles
terminate only in cervical and upper thoracic spinal cord (only affect neck movement)
terminate bilaterally

Question 11

superior colliculus receives input from

Answer 11

cortex, visual systems, auditory systems, and somatic sensory systems (multisensory)

Question 12

two lateral motor systems

Answer 12

rubrospinal tract

lateral cortcospinal tract

Question 13

where are lateral motor systems located?

Answer 13

lateral funiculus and mostly involved in limb movement

Question 14

reticulospinal tract can function as..

Answer 14

indirect corticospinal projection pathway

–>indirect way for cerebral cortex to regulate activity in spinal motor neurons and interneurons

Question 15

what does reticulospinal tract control?

Answer 15

generalized, gross movements

Question 16

what does reticulospinal tract regulate?

Answer 16

gama motor neuron activity

sensory transmission

Question 17

what does RSP contain?

Answer 17

descending autonomic fibers and respiratory control fibers

Question 18

highest level of motor control in humans

Answer 18

cerebral cortex

Question 19

coricospinal functions

Answer 19

• voluntary command for movement

- can regulate sensory transmission through dorsal horn

Question 20

corticobulbar means

Answer 20

cortex to brainstem

Question 21

functions of corticobulbar

Answer 21

affect cranial nerve nuclei (voluntary movement of head and face)
-affect sensory transmission of nuclei
-activate brainstem nuclei involved in movement (indirect corticospinal projections)
project to pons (pontine nuclei) for relay to cerebellum

Question 22

brainstem projections to spinal cord (indirect pathway from cerebral cortex to spinal cord)

Answer 22

superior colliculus

corcioreticular projections

Question 23

precentral gyrus homunculus

Answer 23

feet on medial aspect, head on lateral

more motor cortex devoted to things with finer movements

Question 24

cortical motor neurons do NOT

Answer 24

control the activity of single muslces -->instead, encode particular directions of movement (activate motor neurons that control the several muscles involved in a particular movement and inhibit muscles that would antagonize movement)

Question 25

cortical neuron activity___movement

Answer 25

precedes

Question 26

premotor cortex (including supplementary motor areas)

Answer 26

active during preparations for movements or during rehearsal of movements

Question 27

primary motor cortex does not become active until

Answer 27

movement is actually initiated

Question 28

internal capsule contaisn

Answer 28

corticofugal axons that connect cerebral cortex with the brain stem and spinal cord Head, Arm, Leg

Question 29

corticobulbar fibers

Answer 29

control voluntary head movements--genu | control arm and leg--posterior limb

Question 30

small percentage of cerbral peduncles are occupied by fibers controlling

Answer 30

head and limb movements

Question 31

targets of corticobulbar tracts

Answer 31

``` pontine nuclei (relay to cerebellum) cranial nerve nuclei (esp facial) eye movement control indirect corticospinal tracts sensory nuclei (regulate transmission) visceral centers (respiration) ```

Question 32

hypermimia

Answer 32

some upper motor neurons in anterior cingulate cortex control emotional movements of face--do not project to facial nucleus, so sometimes severe paralysis of voluntary facial movements can lead to increased movement of face to emotional stimuli dont go through the internal capsule

Question 33

supranuclear facial weakness

Answer 33

lesion is above the level of facial nuclei therefore producing lower face weakness CNS lesions rostral to level of facial nucleus

Question 34

damage to facial nerve/nerve

Answer 34

entire face becomes weak

Question 35

cerebral cortex can influence

Answer 35

motor neurons

Question 36

activity in many supporting and stabilizing muscles produced by

Answer 36

indirect corticospinal projections

Question 37

descending motor tract functions

Answer 37

direct: directly influence alpha motor neurons via corticospinal tract indirect: reflex excitation via interneurons, gama loop (reflex contraction to new set point)

Question 38

lateral vs medial motor systems

Answer 38

lateral- precise, limb | medial- course, axial and proximal limb

Question 39

tectospinal tract

Answer 39

superior colliculus (midbrain)-->dorsal tegmental decussation-->MIF-->anterior funiculus-->upper thoracic levels--medial part of intermediate grey bilaterally

Question 40

job of tectospinal

Answer 40

reflex head and arm movement to visual and auditory stimuli

Question 41

medial vestibulo tract

Answer 41

medial vestibulonuclears-->MIF-->anterior funiculus

Question 42

job of medial vestibulotract

Answer 42

adjust of head to vestibular stimuli (stabilizes head when body moving)

Question 43

pontine reticulospinal tract

Answer 43

reticularformation of pons (paramedian pontine reticular formation)-->MLF

Question 44

job of pontine reticulospinal tracts

Answer 44

head turning with horizontal eye movements

Question 45

corticobulbar-->brainstem (superior colliclus, corticoreticular projections)

Answer 45

-->spinal cord | indirect pathway from cerebral cortex to spinal cord

Question 46

corticobulbar-->pontine nucleus

Answer 46

-->cerebellum

Question 47

corticospinal tract

Answer 47

motorcortex (precentral gyrus)-->internal capsule-->cerebral peduncle-->pass through pons-->medullary pyramids--> 90% decussate right at pyramidal decussation-->lateral funiculus-->lateral corticospinalt ract-->mostly interneurons but few motor neurons - ->10% go to anterior funiculus to move axial muscles and some go to dorsal horn for sensory transmissiona nd reflexes - ->

Question 48

cerebrocortical motor neurons

Answer 48

- ->motor neurons in spinal cord-->muscle | * *time lag**

Question 49

initaition of movement

Answer 49

movement that requires a decision premotor cortex (supplementary motor area)-->primary motor cortex

Question 50

latearl vestibulospinal

Answer 50

lateral vestibular nucleus-->in lateral VSTract-->anterior part of lateral funiculus-->all spinal levels

Question 51

fx lateral vestibulospinal

Answer 51

extensors! | vestibulo-righting reflex--increased activity in extensors in right side of body when head tips to right

Question 52

medullary reticulospinal/lateral reticulospinal

Answer 52

medulla-->courses bilaterally in anterior part of lateral funiculus to all spinal ells *mostly inhibitory interneurons in spinal cord--gross control via gama motor neurons and activity regulated by corticobulbar tract

Question 53

reticulospinal tracts

Answer 53

red nucleus (inputs from cortex & cerebellum)-->ventral tegmental decussation (midbrain)-->lateral funiculus->all spinal levels except cervical-->intermediate gray matter interneurons and in dorsal horn

Question 54

job of reticulospinal tract

Answer 54

proximal limb flexor muslces (crawling)

Question 55

cortico-reticulo-spinal

Answer 55

most important corticospinal pathway premotor & supplementary motor cortex (rostal to primary motor cortex)-->medullary reticulospinal pathway **inhibits spinal reflexes, so damage=increas inactivation