Final Flashcards
Name the 6 parts of the CNS that are involved in complex movements
Cerebral Cortex Basal Ganglia Cerebellum Thalamus Brain stem Spinal Cord
What kind of arrangement does the primary cortex have
Somatotopic
What sections of the primary motor cortex is considered premotor
anterior and lateral portions
Where does the premotor area of the primary motor cortex project to?
Primary order motor cortex and basal ganglia
Does the primary motor cortex stimulate movements or contract single muscles?
Stimulate movements
What part of the brain does the supplemental motor area lie in?
Mainly in longitudinal fissure
What are the 4 functions of the supplemental motor area
attitudinal movements
fixation movements
positional movements of head and eyes
background for finer motor control of arms/hands
What are the 3 areas the corticospinal tract originates
Primary motor cortex (30%)
Premotor and supplemental areas (30%)
Somatic sensory areas (40%)
What spinal tract makes up the pyramids and medulla
cotricospinal tract
Where do most corticospinal tract fibers run? Do they all run in same area
They cross midline and form the lateral corticospinal tract
No; some fibers stay ipsilateral and form ventral corticospinal tract
True or false the corticospinal tract lies between the caudate and putamen
True
If all the spinal tracts were cut and the spinal cord was completely separated from brain what would happen?
Flaccidity or “floppy paralysis”
What would happen if spinal cord was cut at mid collicular level? (Decerebrate preparation)
Extensors would be tonically hyperactive “decerebrate rigidity”
What would happen if there was destruction of the cerebral cortex (Decorticate preparation)
Different type of rigidity - “Decorticate spasticity” - tonic excitation from upper area of the reticular formation no longer under inhibitory cortical influence.
What percentage of intracerebral hemorrhages result in decorticate spasticity?
60%
What is decerebration? What does it result in?
Experimental procedure; transection of midbrain at intercollicular level
Loss of sensation; and motor control is profoundly altered
In decerebration does the brain stem control stay intact? Are cortical descending pathways interrupted?
Yes it stays intact
yes they are interrupted
In decerebration what happens to flexion reflexes? What about stretch reflexes?
Flexion reflexes are suppressed
Stretch reflexes are exaggerated
If a patient showed signs of decerebration what would their prognosis be?
Poor
What is “spinal shock”
Initial reaction to cord transection
All cord functions including spinal reflexes are depressed (lack of tonic excitation)
At the onset of clockwise rotation (to the right), what would you expect happens in the VIII cranial nerve on the left side?
Decrease in firing rate
After 20 clockwise (to the right) rotations with the eyes closed on a revolving stool, the subject is abruptly stopped, and the eyes are opened.
What is observed?
Lateral nystagmus with the slow component clockwise
When supine, head tilt is best detected by what?
Saccule
When standing, head tilt is best detected by what?
Utricle
True or false, signals from neck proprioceptors typically augment signals from the vestibular apparatus as the head and neck are rotated and have similar effects on limb flexion and extension. What would make this statement the opposite of the answer?
False
Signals from neck proprioceptors would oppose not augment (assist)
In backward sway, what sequence of contraction of muscles to maintain balance would occur?
Tibialis, then quadriceps, then abdominals
In forward sway, what sequence of contraction of muscles to maintain balance would occur?
Gastrocnemius, then hamstrings, then paraspinals
What would happen to a repetitive simple stretch reflex, if when the muscle contracts it destabilizes posture?
it would be inhibited
What would happen to a repetitive simple stretch reflex, if when the muscle contracts it stabilizes posture?
It would be facilitated
Of the four pathways: striatospinal spinocerebellar nigralstriatal rubrospinal
Which pathway doesn’t exist?
Striatospinal
Which basal ganglia circuit plays a major role in cognitive control of motor activity?
Caudate circuit
Which basal ganglia circuit plays a major role in subconscious control of motor activity?
Putamen circuit
True or false; one’s sense of upright is generally a combination of cues that include both visual and vestibular information
True
What effect does the striatum have on the substantia nigra?
inhibitory GABA projections
What effect does the substantia nigra have on the striatum
inhibitory dopamine projections
Which area acts as a comparator, comparing intention with actual motor performance, and can effect the cerebellum via climbing fiber input?
Inferior olivary nucleus
Strong stimulation of one climbing fiber would elicit what response
complex action potential from a few purkinje cells
Strong stimulation of one mossy fiber would elicit what response?
simple action potential from many purkinje cells
Spontaneous and continuous writhing movements (athetosis) is associated with a lesion in what area?
globus pallidus
Hemibalistic movements are associated with a lesion in what area?
Subthalamus
A patient presents with a resting tremor, lead pipe rigidity in the extremities. Voluntary movements are accurate but slow. Where is a lesion likely to be found?
Basal ganglia
A patient presents with a intention tremor, where is a lesion likely to be found?
Cerebellum
A patient presents with ataxia, upon examination they are unable to perform rapid alternating movements, and unable to check movements (rebound) of the right arm. Where is a lesion likely to be found?
Right side of cerebellum (cerebellum always ipsilateral)
Is the pathway correct?
Corticopontocerebellorubrothalamocorticospinal
yes
Remember: Correct Pathway Certainly Rough, This Could Suck
CorticoPontoCerebelloRubroThalamoCorticoSpinal
Is the pathway correct?
Corticorubrocerebellopontothalamocorticospinal
No
The ventral spinocerebellar tract gains access to the cerebellum primarily via which peduncle?
Superior
The dorsal spinocerebellar tract gains access to the cerebellum primarily via which peduncle?
Inferior
If you administer yohimbine (an alpha 2 receptor blocker) and then stimulate the sympathetic nervous system, what effect do you expect on the amount of norepinephrine released?
Increased
True or false decreased rate of blood coagulation is associated with SNS (sympathetic nervous system)
False, increased rate of blood coagulation is
Denervation supersensitivity is likely associated with what?
Up regulation of receptors by the target tissue
What is the effect of the SNS stimulation on most vascular smooth muscle
constrict
Inhibitory motor neurons from the myenteric plexus release what neurotransmitters?
Dynorphin
Vasoactive intestinal peptide
A patient presents with a slight ptosis of the left eye, but the right pupil appears dilated compared to the left, and they report that the let side of their face never sweats. What’s your opinion doctor?
Interruption of the left sympathetic supply to the face
On EMG (electromyography), what is the clinical significance of an decreased number of motor units activated during a voluntary muslce contraction?
Possible neuropathy (“n” is less)
On EMG (electromyography), what is the clinical significance of an increased number of motor units activated during a voluntary muslce contraction?
Possible myopathy (“m” is more)
In primary cultures of postganglonic SNS neurons, what inhibits the release of norepinephrine?
GABA
If there is a facilitated spinal segment at T6. What would you expect when 3 kg of pressure is applied to the spinous process at T10 which is not in a state of segmental facilitation
Exaggerated response in adjacent paraspinal muscles at only T6
How much pressure can be applied to a normal vertebrae eliciting only a minimal response in the adjacent paraspinal muscles/
7 kg
True or false the CNS coordinates host defense activity
true
In a spinal cord transection how long does it take for spinal cord neurons to regain excitability. Will the reflexes be normal?
days to weeks
some will be hyperactive
What happens in a spinal mass reflex?
Spinal cord becoming excessively active
flexor spasm and evacuation of bladder and colon
What happens to blood pressure during spinal shock? What about skeletal muscle? Sacral reflexes?
Blood pressure falls dramatically
All skeletal muscle reflexes in cord are blocked
Sacral reflexes for bladder and colon evacuation control are suppressed
What tract transmits excitatory signals in the pontine reticular nuclei?
pontine (medial) reticulospinal tract
What does the pontine reticular nuclei stimulate?
axial trunk and extensor muscles that support body against gravity
Where does the pontine reticular nuclei receive stimulation from?
vestibular nuclei and deep nuclei of cerebellum
True or false, the pontine reticular nuclei has a low degree of natural excitability
False, it has a high degree
What tract transmits inhibitory signals in the medullary nuclei? And what muscles does it communicate with?
Medullary (lateral) reticulospinal tract
and it inhibits the same anti-gravity muscles that the pontine reticular nuclei stimulates
Where does the medullary nuclei receive it’s input?
cortex, red nucleus, and other motor pathways
What are 6 roles of the brain stem in controlling motor function?
Controls: Respiration cardiovascular system GI function stereotyped movements equilibrium eye movement
What are 3 very important ipsilateral descending tracts from brain to spinal cord?
Ventral corticospinal tract
Reticulospinal tract
Vestibulospinal tract
What tract are the pontine (medial) reticular formation and medullary (lateral) reticular formation a part of
Reticulospinal tracts
Where does the vestibulospinal tract get it’s origin
lateral vestibular nucleus to extensors
Name 3 very important contralateral descending tracts from brain to spinal cord
Lateral corticospinal tract
Rubrospinal-innervate mainly flexors
Trecto-spinal-innervate cervical musculature only
What are the two lateral motor descending spinal tracts?
Lateral corticospinal and Rubrospinal
What does the rubrospinal tract mainly control?
distal muscles
What are the 4 medial motor descending spinal tracts, what do they mainly control?
Reticulospinal, vestibulospinal, tectospinal and ventral corticospinal
mainly axial and girdle muscles
Which corticospinal tract fibers form the lateral corticospinal tract
contralateral fibers
What percentage of corticospinal tract fibers originate from areas behind the central sulcus, including the primary somatosensory cortex
40%
Greater than 1/2 of the primary motor cortex is devoted to control of what?
hands and speech (homunculus)
A stroke that lesions the posterior limb of the internal capsule would be associated with what?
loss of voluntary movement
A lesion of high brain stem will result in what?
spasticity
A lesion of middle brain stem will result in what?
rigidity
A lesion of low brain stem will result in what?
flaccidity
Which brainstem area that receives stimulation from the vestibular nuclei and transmits excitatory signals to stimulate the axial trunk and extensor muscles that support the body against gravity/
Pontine reticular nuclei
What does dynamic signals from pyramidal cells cause?
Initiates contraction
What does static signal from pyramidal cells cause?
fire at a slower rate to maintain contraction
Signals for movement originate in the sensory association cortex and output to premotor cortex directly and indirectly via:
Basal ganglia and cerebrocerebellum
Excitatory motor neurons from the myenteric plexus (auerbach) releases what neurotransmitters?
ACH and Substance P
What would a normal muscle look like during activity on a EMG?
no spontaneous electrical activity except at end-plate regions (neuromuscular junctions)
What would an abnormal muscle look like during activity on a EMG?
Spontaneous activation of individual motor units, sharp waves (characteristic of neuropathic disorders like ALS)
What two kinds of movements are included when trying to maintain posture
Static reflexes (sustained contraction) and dynamic short term phasic (transient movements)
What happens to a muscle as muscle spindles lengthen?
muscle contracts
What are the 3 types of postural reflexes?
vestibular
tonic neck
and righting reflexes
What does your vestibular apparatus detect?
sensations of equilibrium
What part of your CNS that is involved in equilibrium contains sacules, utricles, and semicircular canals
Vestibular apparatus
What part of your CNS involved in postural reflexes is embedded in the petrous portion of temporal bone?
Vestibular apparatus
What is the macula? what is it covered in?
Sensory area of the vestibular apparatus (utricle and saccule)
covered in a gelatinous layer
How does the macula detect directional sensitivity?
Hair cells that project in macula project cilia into gelatinous layer
directional sensitive hair cells cause depolarization or hyper polarization
True or false, the utricle and saccule macula can detect linear velocity
False, it can detect linear acceleration though (when in car can tell when accelerating but cannot tell difference between 40 mph or 80 mph)
The macula of the utricle lies mainly in what plane?
horizontal plane
The macula of saccule lies mainly in what plane?
vertical plane
Semicircular canals of the vestibular apparatus contains what structure?
What is that made up of?
Crista ampularis (swelling/ampulla) Cupula loose gelatinous tissue mass
When are the semicircular canals of the vestibular apparatus stimulated?
when head begins to rotate
How many pairs of semicircular canals are there? What are their names?
3
anterior, horizontal and posterior
What are the semicircular canals filled with? What is that substance enriched with?
Endolymph which is enriched with potassium ions
As your head begins to rotate, what is happening in the semicircular canals
fluid lags behind and bends cupula
This generates a receptor potential altering firing rate of CN VIII (projecting onto the vestibular nuclei)
What does CN VIII detect when receptor potentials are altered by fluid lagging in the semicircular canals
detects rotational acceleration and deceleration
What does stimulation of your semicircular canals do to your extensors? What about your eyes?
Causes increased extensor tone Causes nystagmus (slow tracking component)
The vestibular nuclei which receives information from CN VIII and the semicircular canals makes connections with what other cranial nerves and brain structure?
CN associated with ocular movements (III, IV, VI) and cerebellum
This is what can stimulate Nystagmus (drunk eyes)
What can initiate the slow component nystagmus (tracking)
semicircular canals
What can initiate the fast component nystagmus (jump ahead to new focal spot)
brain stem nuclei
What other brain structure does the semicircular canals work closely with to make anticipatory corrections to for equilibrium
the cerebellum (specifically the flocculonodular lobe)
Where does proprioceptive information from the neck project onto?
the vestibular nucleus and cerebellum
True or false cervical joint proprioceptors can override signals from vestibular apparatus to prevent the feeling of dis-equilibrium
true
What is the most common cause of vertigo? What causes it?
Benign paroxysmal positional vertigo
Sudden sensation of spinning, usually when moving head
What would you do for a patient who presented with benign paroxysmal positional vertigo? What is the success rate of this maneuver?
“Epley’s maneuver”
This causes any free floating particles in semicircular canal to relocated (via gravity) and therefore can no longer stimulate cupula relieving vertigo
90 to 95%
True or false, one’s sense of upright is only derived from vestibular information?
False
it is generally a combination of visual cues and vestibular information
(tilting room and chair example from class)
What evokes vestibular reflexes?
changes in head position
What triggers neck reflexes?
tilting or turning of the neck
What are the two major mechanisms of postural adjustments?
anticipatory (feed forward) - predicts disturbance
Compensatory (feedback)
How does your body build anticipatory (feed forward) postural adjustments?
modified by experience; improves with practice
What evokes compensatory (feedback) postural adjustments
sensory events following loss of balance
What would be an example of a extremely rapid postural adjustment?
simple stretch reflex
Would proprioceptive information from your joints and muscles be considered short latency or longer latency information in regards to postural mechanisms
Short latency (~70-100 ms)
What would be an example of longer latency in regards to information in your postural mechanisms
Vestibular or Visual signals (twice as long as proprioceptive information)
True or false, receptors in your skin are not involved in postural adjustments?
False, very high in your feet
Does extension of your neck reflexes facilitate or inhibit extensors of your arms and legs
facilitates
Does flexion of your neck reflexes facilitate or inhibit flexors of your arms and legs?
facilitates
How will rotation or lateral bending of your neck reflexes affect your extensors and flexors
It will facilitate extensors on ipsilateral side
It will facilitate flexors on contralateral side
What are the 4 principle nuclei of the basal ganglia
striatum (caudate and putamen)
globus pallidus
substantia nigra
subthalmic nucleus
What are the 3 input nuclei of basal ganglia
Caudate
Putamen (together striatum)
Nucleus accumbens
What are the 4 output nuclei of basal ganglia
Globus pallidus (external segment)
subthalamic nucleus
substantia nigra
ventral segmental area
True or false, basal ganglia has direct input/output with spinal cord
False, it does not have direct input/output
Disorders of the basal ganglia have 3 characteristic types; what are they?
tremor and other involuntary movements
changes in posture and muscle tone
poverty and slowness of movement
What is athetosis? What causes it?
spontaneous and continuous writhing movements
lesion in globus pallidus
What is hemiballismus? What causes it?
sudden violent flailing movements of limbs
lesion of sub thalamus
What is chorea? What causes it?
flicking movements in hands, face (“dance” from CNS)
multiple small lesions of putamen
Rigidity, akinesia, resting tremors (parkinson’s) are all associated with issues of what area?
Substantia nigra
What % of the brain’s mass comes from the cerebellum?
10%
True or false, the cerebellum contains greater than half of the brains neurons
True
True or false, complete destruction of the cerebellum would produce severe impairment on sensory processes, and result in loss of muscle strength
False, it wouldn’t effect either of those
What does the vestibulocerebellum govern? What is its input/output nuclei? What is another name for it?
Governs eye movement and body equilibrium
Vestibular nuclei (input and output)
Floculonodular lobe
What does the spinocerebellum play a major role in? What is its input/output? What is another name for it?
Major role in movement, influencing descending motor systems
Input: periphery and spinal cord
Output: cortex
Vermis and intermediate lobes
What does the cerebrocerebellum control? (3 things)
Planning and initiation of movement and extra motor prediction
Mental rehearsal of complex motor actions
conscious assessment of movement errors
What is the input/output of the cerebrocerebeullum? What is another name for it?
Input: pontine nucleus
output: pre and motor cortex
Lateral zone
What is the major inhibitory cell of the cerebellar cortex? (inhibits and projects to the deep cerebellar nuclei)
purkinje cells
How do complex action potentials differ from simple action potentials from purkinje cells? (hint: what fibers do each travel in, ratio of fiber to purkinje?)
Complex AP: from climbing fibers via inferior olivary nucleus (1:1 ratio of climbing fibers to purkinje)
Simple AP: from mossy fibers via granule cells (1 mossy fiber excites hundreds-thousands of purkinje cells)
Mossy fibers come from everywhere EXCEPT inferior olivary nucleus
A patient with lesions of the cerebellum would present with symptoms on which side of the body compared to the lesion?
Ipsilateral
True or false the cerebellum is loaded by the integrity of joint mechanoreceptors
True
Name the 3 deep nuclei of the cerebellum
Fastigial
Interposed (globose and emboliform)
Dentate
Does the superior peduncle of the brain stem project afferent or efferent fibers or both?
Both afferent and efferent
Does the middle peduncle of the brain stem project afferent or efferent fibers or both?
Efferent only
Does the inferior peduncle of the brain stem project afferent or efferent fibers or both?
Afferent
True or false, the cerebellum receives info about plans for movement from brain structures concerned with programming and executing movement? If so, what is this called?
True
corollary discharge/internal feedback
True or false, the cerebellum receives info about motor performance from peripheral feedback while you’re moving. If so, what is this called?
True
reafference/external feedback
Who proposed the idea of homeostasis?
Walter Cannon in 1932
During the same time Walter Cannon proposed the idea of homeostasis, what other idea did Cannon introduce?
negative feedback regulation
What are the 3 major divisions of the autonomic nervous system (ANS)
Sympathetic (Fight or Flight)
Parasympathetic (Rest and Digest)
Enteric (GI tract)
Smooth muscle, heart muscle, and exocrine glands are all controlled by what system?
Autonomic Nervous System (ANS)
Pre-ganglionic sympathetic cells release mainly what neurotransmitter?
acetylcholine (ACH)
sometimes releases neuropeptides (LHRH)
Post-ganglionic sympathetic cells release mainly what neurotransmitter?
norepinephrine
sometimes releases neuropeptides (NPY)
Pre-ganglionic sympathetic cells reside in the lateral horn at what spinal nerve levels?
C8-L2 or L3
Paravertebral and Prevertebral ganglia are associated with what kind of ganglionic cells?
Post-ganglionic sympathetic cells
True or false, post-ganglionic sympathetic cells that release norepinephrine can regulate them selves? (negative feedback) If so, what makes this possible?
true
the presence of alpha 2 receptors allows norepinephrine to bind to the receptors and regulate itself
What substance can block alpha 2 receptors that would regulate the breakdown of norepinephrine? What would the presence of this substance do to the amount of norepinephrine released?
Yohimbine
It would increase
How many impulses a second are there in a normal sympathetic tone?
1/2 to 2 impulses a second
What is sympathocotonia?
Increased sympathetic activity (hyperactivity)
What is Horner’s syndrome? what are 4 symptoms?
Interruption of sympathetic supply to head Partial ptosis (drooping eyelid) Pupillary constriction Anhydosis (in ability to sweat) Enophthalmos (retraction of eyeball into socket due to lack of innervation to smooth muscles of eye)
Edinger-Westphal nucleus is a part of what parasympathetic CN
III
The superior salivatory nucleus is a part of what parasympathetic CN
VII
The inferior salivatory nucleus is a part of what parasympathetic CN
IX
The dorsal motor, and nucleus ambiguus is a part of what parasympathetic CN
X
What does the nucleus ambiguus do?
bradycardia or slows heart rate
The ciliary, pterygopalaine, submandibular, and otic ganglia are all post-ganglionic or pre-ganglionic parasympathetic ganglia?
Post-ganglionic parasympathetic
Which parasympathetic CN innervates the heart, lungs, bronchi, liver, pancreas, and almost all of the GI tract?
X the Vagus nerve
What affect does Norepinephrine have on intestinal motility and sphincters?
Slows/Contracts
Norepinephrine and Somatostatin have what effect on intestinal secretion?
inhibit
Pre-ganglioninc parasympathetic stimulation of the GI tract will cause what?
increase motility and tone
relax sphincters
stimulate secretion
(remember Parasympathetic = Rest and Digest)
The myenteric plexus (Auerbach) controls peristalsis by releasing what hormones?
Excitatory = ACH and Sub P Inhibitory = Dynorphin and vasoactive intestinal peptide (VIP)
What excitatory neurotransmitter do visceral afferent fibers release?
Glutamate
Can also release neuropeptides (VIP, Sub P, Somatostatin, CCK, etc.)
True or false, release of norepinephrine can increase membrane permeability
True
It effects G proteins —-> releasing cAMP —> increases protein kinases —–> increasing permeability
Sympathetic effect on eyes
dilate pupils
Sympathetic effect on glands
increases concentrate secretion because decreases blood flow to area
Causes sweat glands to stimulate
Sympathetic effect on GI
inhibit
Sympathetic effect on heart
stimulate
Sympathetic effect on blood vessels
constrict
Parasympathetic effect on eyes
constrict pupil, ciliary muscles, and increase lens strength
Parasympathetic effect on glands
stimulated
Parasympathetic effect on GI tract
stimulated
Parasympathetic effect on heart
inhibit
Parasympathetic effect on blood vessels
largely absent
Parasympathetic effect on airways
constrict
Parasympathetic effect on ducts
constriction
Parasympathetic effect on immune
unknown
Sympathetic effect on airway
dilation
Sympathetic effect on ducts
dilation
Sympathetic effect on immune
inhibits
Tyrosine is the precursor for what?
Dopamine, norepinephrine and epinephrine
Nicotinic and muscarinic are both receptors for what neurotransmitter?
ACH
