L11: Central Control of Movement Flashcards
4 lobes of the cerebral cortex
- Parietal (tactile sensations)
- occipital (visual)
- temporal (auditory, memory)
- frontal lobe (motor processing, decision making , mood)
UMNs start in the motor cortex & reach lower motor neurons via what two tracts
corticospinal or corticobulbar
where do the corticobulbar pathways terminate
brain stem
where do the corticospinal pathways terminate
spinal cord
what cranial nerves are exclusively efferent motor pathways
III: oculomotor
XI: accessory
XII: hypoglossal
what cranial nerves are mixed pathways (sensory and motor)
IV: Trochlear and VI: Abducens
what cranial nerves are exclusively afferent sensory nerves
I: olfactory
II: optic nerves
VIII: vestibulochlear
neurons of the corticobulbar tract arise from the ______ and synapse on the LMNs of the _______
lateral primary motor cortex
synapse on LMNs of the brainstem
which CNs are LMNs
III-VII, IX-XII
which cranial nerves are tested in the pupillary light reflex
II and III
LMNs of the _______ tract run through the cranial nerves and determine motor control of the head and neck
Corticobulbar tract
The corticospinal tracts arise from the ______ and synapse with LMNs in the ______
motor cortex
ventral horns
LMNs then exit the CNS
UMNs decussate at the caudal end of the medulla near medullary structures called the ?
Pyramids (hence Pyramidal tract)
LMNs from the _____ part of the ventral horn innervate muscles of the distal limbs
lateral
LMNs from the _____ part of the ventral horn innervate muscles of the proximal limbs
ventral
neurons of the extrapyramidal system are located where
nuclei of the brainstem
- red nucleus
- reticular formation
- vestibular nucleus
- tectum
damage to any of the extrapyramidal tracts is associated with what
hypertonic and hypotonic pathology (depending on which tract is affected)
condition caused by increased muscle tone and stretch reflexes, particularly the extensor muscles, resulting in extensor hypertonia
seen in hit by car accidents
Decerebrate rigidity
what is opisthotonus
spasm of muscles causing backward arching of the head and neck
the red nucleus forms the _______ tract
Rubrospinal
the reticular formation forms the _____tract
reticulospinal
the vestibular nucleus forms the _____tract
vestibulospinal
the tectum forms the _____tract
tectospinal
the rubrospinal tract sends input down the _____ white matter and the _____ part of the gray matter to the _____ musculature
lateral
lateral
distal
the reticulospinal, tectospinal and vestibuospinal tracts all send input through the ____ white matter, and the ______ part of the gray matter to the _____ musculature
medial
medial
axial and proximal musculature
the red nucleus receives input from the _______ and _______
motor cortex and cerebellum
Rubrospinal tract neurons provide _____ to LMNs that control _____ muscles in the neck and proximal lumbs, buts inhibition to _______ muscles in the limbs
excitation
flexor
extensor
is rubrospinal activation voluntary or involuntary
involuntary
damage to the rubrospinal tract causes _________
extensor hypertonia
Pontine reticulospinal tract neurons _____ alpha and gamma neurons to extensor muscles
excite
medullar reticulospinal tract neurons _____ the pontine tract, therefore _____ extensor muscles
inhibit
inhibiting
lesions to the excitatory fibers of the reticular formation can result in ________ and this tends to occur in the ______ reticulospinal tract
hypotonia (flaccidity)
Pontine
lesions to the inhibitory fibers of the reticular formation can result in ________ and this tends to occur in the _____ reticulospinal tract
hypertonia (and spasticity)
medullar tract
the vestibular nuclues receives input from the vestibular appartarus of the _____ and ______
inner ear and cerebellum
what tract contains sensory info on the position of the head
vestibulospinal
what tract controls body position and disturbances in balance
vestibulospinal
damage to the vestibulospinal tract causes ?
extensor hypotonia
this allows for a balance in the descending influences onto extensor and flexor muscles AND alpha gamma coactivation
pontine tract neurons excite extensor muscles while medullar tract neurons inhibit the pontine tract to inhibit extensor muscles
in the tectospinal tract, the superior (rostral) colliculus receives what input
visual, auditory and somatosensory input
about environmental stimuli
this tract is involved in reflex orientation of the head and eyes towards environmental stimuli and controls the axial and proximal musculature of the head
tectospinal tract
Damage to this tract may cause disruption in the ability to orient the head towards and fix gaze on an object
tectospinal
damage to ____neurons can cause an inability to move; hyperreflexia; increased muscle tone or muscle atrophy
UMNs
Extrapyramidal tracts exert control on _____neurons to increase _____ control
they can also interact with ____ nuclei and the ______ to fine tune motor control
Lower Motor Neurons
Fine control
Basal nuclei & the cerebellum
cerebral palsy results in spasticity of skeletal muscles, this is an example of damage caused to _____neurons
Upper motor
what three things are lower motor neurons innervated by
- Upper motor neurons
- extrapyramidal neurons
- reflex arcs
what is the function of LMNs
stimulate muscles
what can be caused from damage to LMNs?
- innapropriate or absence of movement (hyporeflexia, flaccid muscles, paraplegia)
- muscle atrophy
- reduced muscle tone
what is muscle tone
the resting level of tension in a muscle as a result of alpha motor neurons
reduced muscle tone results from damage of an _____motor neuron
alpha (LMN)
increased muscle tone can result from damage to a ___neuron
upper motor neuron
disturbs the balance of supraspinal inhibitory and excitatory inputs, producing a state of net disinhibition
Decerebrate rigidity results from a ____ lesion
midbrain
what is the major regulator of alpha motor neuron discharge
activity of muscle spindles
explain alpha gamma coactivation
the gamma efferent sytem regulates the resting level of activity in spindle afferenta dn establishes a baseline level of alpha motor neuron activity in the absence of muscle stretch
