Exam 2 Material : Movement Flashcards
reflex
simple, stereotypes, unlearned response to a particular stimulus
used to automatically protect the body
How do reflexes work?
- stimulus activates a sensory receptor
- impulse travels via dorsal horn to spinal cord
- integration at spinal cord
- impulse travels by motor pathway to exit spinal cord
- an effector responds
What do reflexes do?
bypass the brain and go straight to the muscles
Movement has how many neuron processes?
2
motor plan (motor program)
set of muscle commands established BEFORE the action occurs
BRAIN!!
muscles interact with the nervous system via
motor neurons
upper motor neurons
cell bodies in motor cortex (voluntary movement)
synapse in spinal cord
lower motor neurons
cell bodies in spinal cord exit through ventral root
- directly command muscle contraction
- synapse on msucles
synapse between motor neurons and muscle fibers
neuromuscular junction
Motor neurons release _______ to cause muscle contraction at the neuromuscular junction
acetylcholine
primary motor cortex (M1)
- in precentral gyrus
- initiation of voluntary motor movements
“I want to pick up my pencil”
motor homunculus
lots in hands, lips, tongue (fine motor movements)
less in back
Parts of the motor cortex
- posterior parietal lobe
- prefrontal cortex
- premotor cortex
- supplementary motor area (SMA)
posterior parietal lobe
proprioceptive clues about body position
- to continue carrying out a movement, getting closer to picking something up
prefrontal cortex
decision making
- “should I pick this up”
premotor cortex
programs movement by combining information from prefrontal cortex and posterior parietal cortex
- integrates to know where you need to move to
- efferent project to supplementary movement area
supplementary motor area (SMA)
initiation of movement sequences, preplanned levels
- move fingers before your elbow when you are picking something up
Where are mirror neurons?
in a sub region of the premotor cortex (F5)
mirror neurons
the same neurons fire BEFORE making a movement as when observing another individual do the same movement
- activated when about to mimic someone’s actions
basal ganglia
group of interconnected forebrain nuclei that modulate movement
Where does the basal ganglia receive info from?
- primary and secondary motor areas
- somatosensory cortex
Functions of the basal ganglia
- smooth movements through the thalamus
- learning movement sequences preformed as a unit
- once a task is learned BG kicks in (automatic)
- like playing the violin, your fingers know where
to go after playing for years , no thought
rubrospinal tract : where are the upper motor neurons?
red nucleus
rubrospinal tract function
bending, straightening limbs
vestibulospinal tract : where are upper motor neurons?
vestibular nuclei
vestibulospinal tract function
balance, posture, compensates for tilting
tectospinal tract: where are upper motor neurons?
superior colliculi
tectospinal tract function
avoidance reflexes (dodging a ball thrown at you), turns neck so eyes can follow moving object (tracks visual movement)
reticulospinal tract: where are upper motor neurons?
reticular formation
reticulospinal tract function
startle and escape movements
- when scared
corticobulbar tract controls movement of
face, tongue, eye muscles
upper motor neurons originate in
motor cortex
upper motor neuron axons decussate…
in the pons and synapse on lower motor neurons in the pons and medulla
several ______ serve as lower motor neurons
cranial nerves
Cranial nerves involved in lower motor neurons
- trigeminal
- facial
- glossopharyngeal
- vagus
- spinal accessory
- hypoglossal
(5,7,9,10,11,12)
spinal cord _____ involved in voluntary movement of the face
is NOT
the cerebral cortex controls ______ via commands sent through 2 major pathways in spinal cord
body muscles
2 parts of the corticospinal system
- lateral corticospinal tract
- ventral corticospinal tract
movements of distal limbs (arms, hands, fingers, toes, lower legs, feet)
lateral corticospinal tract
movements of upper legs, upper arms, and trunk
ventral corticospinal tract
lateral corticospinal tract
upper motor neuron cell bodies originate in
primary motor cortex (M1)
lateral corticospinal tract
what is it called when axons descend through brain and decussate after the medulla
pyramidal decussation
lateral corticospinal tract
first synapse
spinal cord
lateral corticospinal tract
lower motor neurons innervate skeletal muscle
where is second synapse
muscles in extremities
what is the lateral corticospinal tract important for
grasping and manipulating objects
ventral corticospinal tract
upper motor neuron cell bodies originate in
primary motor cortex (M1)
ventral corticospinal tract
how do the axons decussate
ipsilaterally
right before synapsing on lower motor neurons in spinal cord
ventral corticospinal tract
lower motor neurons innervate…
skeletal muscle
what is the ventral corticospinal tract important for?
locomotion and posture
How does the basal ganglia indirectly influence the lower motor neurons?
thalamus and cortex
- it does not directly project to the spinal cord
In the absence of voluntary movement…
- no dopamine in system
2. circuitry driven by only glutamate from cortex
- chorea (brief, jerky movements)
- dystonia (abnormal postures)
- indirect pathway dysfunction (specific damage to GABA neurons controlled by D2 receptors
Huntington’s disease early motor signs
- executive function
- recent and remote memory
cognitive abnormalities associated with huntingtons disease
psychiatric changes in huntingtons diseases
- depression, psychosis (dementia)
Huntington’s disease pathology (pathway)
- GABA neurons with D2 receptor are gone
- get random glutamate from cortex
- GPe disinhibited since nothing from D2
- shuts down STN activity so GPi can not get glutamate
- no GABA to thalamus so thalamus is disinhibited
- thalamus wants to move so you will get involuntary movements
pathophysiology of Parkinson’s Disease
loss of nigrostriatal dopamine projection
3 broad categories of types of symptoms in PD
motor, mood, dementia/cognitive dysfunction
4 motor symptoms in PD
- tremor
- bradykinesia
- rigidity
- loss of postural reflexes
The cerebellum receives info from M1 about an intended movement and determines the _____
order and timing of muscle contractions
The cerebellum uses info from the vestibular system to…
- maintain posture and balance
- refine movements
- control eye movements that compensate for head movements
the cerebellum receives a copy of the motor plan that muscles will receive from the…
motor cortex
as movement proceeds, cerebellum gets proprioceptive signals about the actual motor performance from the…
vestibular system
cerebellum compares the plan to the
actual movements
cerebellum sends corrective signals to
cortex and brainstem
