Normal Neuro Flashcards
The electrical activity flows from cell body down to the
synapse
Na is normally found ____ the cell
Outside
K is normally found ____ the cell
inside
What helps increase the speed on conduction?
Myelin
What is myelin produced by in CNS?
Oligodendroglial cells
What is fast action potential propagation along myelin channels called?
Saltatory conduction
WHat type channels allow Na to flow in and K to flow out?
Voltage gated ion channels
What type things determine the action potential conduction in nerve axons?
Axon diameter (larger is better for conduction) Myelin
What produces myelin in the PNS?
Schwann cell
What type of axons are pain, thermal, autonomic axons associated with?
small diameter unmyelinated axons
When diseases affect myelin, what happens?
Leads to dysfunction due to lack of myelin regeneration, signal can’t be transmitted as quickly
What are proprioception axons associated with?
Large diameter myelinated axons
What are tactile, motor axons associated with in terms of axon?
Medium diameter, lightly myelinated
When nerve impulse arrives at terminal what happens with calcium?
Binds to the receptor and causes the synaptic vesicles to release their neurotransmitter (NT) into the synaptic cleft
How is NT taken out of synaptic cleft?
By a enzymes in post-synaptic terminal
Reuptake in pre-synaptic terminal
These are all common what?
Acetylcholine, Norepinephrine, Dopamine, Serotonin, GABA, Glycine, Glutamate, Substance P
Neurotransmitters
What is the sites of actions of many drugs?
Synaptic cleft and associated receptors
What are the slowest conducting fibers?
Pain
slowest are the suffering aspect
larger fibers associated with pain allow you to what?
Localize the pain (why you can tell where the pain is before you feel the pain)
When type of fibers cross at the spinal cord?
Pain; go from grey matter to white matter at this point
What type of fibers do not cross at the spinal cord?
Proprioception, tactile
How much overlap is there on midline for somatic dermatomes?
3-5 cm
What is the pain and termal pathway from the body called?
Spinothalamic (starts in spinal cord, goes to thalamus)
What is the thalamus?
Integrator of all sensory information coming in
After going through the thalamus, where does the spinothalamic tract go?
To postcentral gyrus
If you have a lesion in the medulla, where will you lose pain sensation?
Contralateral side
If you have a lesion in the medulla, where will you lose motor movement?
Ipsilateral side
In the spinothalamic (anterior, lateral) tract what happens are neurons come up from spinal cord?
They collect together
What position does the pain pathway (spinothalamic tract) maintain up through the brainstem?
Lateral position
Where does pain come to conscious appreciated?
Contralateral cerebral cortex (post central gyrus)
What cerebral artery services the lateral surface of the post central gyrus?
Middle cerebral artery
Why is there referred pain?
Skin and developing organ get innervated by the same level, but then organ descends
Where can you have pain from the gallbladder and liver?
Right shoulder
Visceral pain is poorly _____
Localized
What is visceral pain originating in an organ and “felt” on the body surface?
Referred pain
Where does pain with the appendix usually start?
Umbilical area because appendix first irritates visceral peritoneum
Onces irritation of appendix spreads to parietal peritoneum and body wall- where does it “moves” (this is somatic pain)
RLQ
What is involved in the conscious proprioception pathway?
Discriminative tactile
Vibratory
Position Sense
What is discriminative tactile sensation?
Being able to discriminate things based on feel alone
Where does conscious proprioception pathway go to
Post central gyrus
What is know where your body parts are in space?
Proprioception
Ways to test proprioception
Identify items in hand w/o looking
Identify a number on traced on your hand
Big toe moved by clinical and patient reports toe position (has whole pathway)
Where is the conscious proprioception pathway?
Dorsal columns of the cord
Where do the dorsal columns cross?
Brainstem (medulla)
doesn’t cross in spinal cord
What are the two aspects of the dorsal columns?
Fasciculus gracilis (lower half of body) Faciculus cuneatus (upper half of body)
What is a sign where patient looses sense of balance w/ feet together and eyes closed (indicated dysfunction of dorsal columns)
Rhomberg sign
What type patient is a Rhomberg sign seen in?
Multiple sclerosis (tend to fall as soon as they close their eyes)
Where are the synaptic nuclei in the dorsal columns pathway?
Medulla
In the medulla, where is the dorsal columns pathway located?
Medially
Where do pain and thermal pathway of trigeminal enter then go?
Enter at pons then go down through the lateral aspect of the brainstem, crossing at the medulla then coming up medially
If an individual losses pain and thermal sensation on the ipsilateral side of the face, but on the contralateral side of the body- where is the lesion?
Pons/ medulla lateral region
When do tactile and proprioception fibers of the trigeminal cross?
Right when entering the medulla
Where do non-conscious proprioception fibers go?
cerebellum and vesicular nuclei in the brainstem
An injury to the spinocerebellar tract causes what?
Ataxia
What direction does the voluntary motor pathway go?
Descending
What controls the reticular formation?
Hypothalamus
What type neurons does the reticular formation affect?
Parasympathetic,
What do descending axons of the reticular formation modulate?
Pain
What are the three things that modulate pain?
Reticular formation
Periaquiductal gray
Raphe’ nuclei (center of brainstem)
What sends axons to the Raphe nuclei?
Trigeminal
Ascending pain path from contralateral body
(Raphne nuclei is where most of these end)
Pain pathways send tremendous amounts of axons into the…
Raphe nuclei, which go up to the thalamus and hypothalamus
Raphe nuclei project _____ to the trigeminal nuclei & dorsal horns enkephalin neurons.
serotonin
_____ inhibits trigmenial and dorsal horn pain transmission neurons.
Enkephalin
Serotonin goes down the enkephalin neuron which then synapses with a neuron in the DRG causing it to be____
inhibited
What other fibers also activate enkephalin inhibitory neuron?
Tactile fibers (why massaging a injured muscle can help, acupuncture)
Where is the precentral gyrus located?
Anterior to the central fissure
The motor areas serve the _____ aspect of the body
Contralateral
What neurons do the precentral gyrus contain?
Neurons for initiating a movement
Where do you deposit information of how to do a learned movement?
Supplemental Motor Area (SMA)
Which area “integrates visual, spatial, tactile and proprioceptive sensory data; important in sequencing and visual guidance of complex movements.”
Somatosensory area (SSA)
What artery supplies the lateral side of the brain?
Middle cerebral anterior
What artery supplies the medial side of the brain?
Anterior cerebral artery
The lower extremity is located on the _____ aspect of the precentral gyrus.
Medial
What is the internal capsule?
Continuation of white matter of the central hemisphere.
Within this structure are the axons from the cortex going down to form the motor pathway
What are the three components of the basal ganglia?
Caudate
Putamen
Globus pallidus
What are the two parts of the internal capsule?
Anterior part (limbic) Posterior part (fibers than innervate CNs)
What are the two tracts of the upper motor neurons of the descending motor pathway?
Corticospinal tract to spinal cord
Corticonuclear tract to cranial nerves
What descending motor pathway has mostly crossed axons serving the contralateral face, but with some cranial nerves receiving ipsilateral input?
Corticonuclear tract
What descending motor pathway has axons that cross to the contralateral spinal cord in the medulla, and innervate motor neurons in the contralateral cord?
Corticospinal tract
What two aspects make up the lower motor neurons of the descending motor pathway?
Motor neurons of cranial nerves
Motor neurons of spinal cord
Does the descending motor pathway (corticospinal tracts) synapse in the brain stem?
No- don’t synapse until they reach the lower motor neuron
What do lower motor neurons innervate?
Skeletal muscle
Both cortices innervate what part of the face equally?
Forehead
What cortex innervates the lower Right side of the face?
Left cortex
What does a peripheral lesion involving the facial muscles effect?
Motor neuron going to the muscle. Lose all function on that side of the face
What does a central lesion involving the facial muscles effect?
Upper motor pathway, rostral to facial nucleus (pons).
What symptoms will you have with a central lesion involving the facial muscles?
Lose movement of the lower, contralateral side of the face
What lobe of the cerebellum receives input from the musculoskeletal system and controls non-conscious proprioception and position sense?
Anterior lobe
What lobe of the cerebellum gets input from the motor cortex about the next intended movement?
Posterior lobe
What lobe of the cerebellum receives input from the vestibular system for balance and reflexes related to gravity & movement?
Fllocculonodular lobe
What are the three cerebellar peduncles?
Superior
Middle
Inferior
What is found in a peduncle?
Largely myelinated axons
What would a lesion to the cerebellum result in?
Inability to make a movement accurate, strong, and in time
Ataxia, intension tremor
What cerebellar peduncle gives input to the cerebellum from the vestibular system and spinocerebellar tracts?
Inferior peduncle
What cerebellar peduncle gives input to the cerebellum from the motor cortex concerning the next motor movement?
Middle peduncle
What cerebellar peduncle gives output of the cerebellum to the thalamus and motor cortex. Informs cortex of body position, limb orientation, movement and tension on musculoskeletal structures?
Superior peduncle
What peduncle does an intension (action) tremor usually involve
Superior peduncle
What is an intension (action) tremor?
Individual is fine standing still, but start to shake as soon as they move. Only shows up when they try to make a movement. Seen mostly on one side
What side of the body does the cerebellum take care of?
Ipsilateral
What do patients with cerebellar dysfunction often complain of?
Dizziness and weakness with eyes open
What is an essential tremor?
Where an individual has a tremor at all times. Head and upper extremities affected first than moves downward
Do lesions in the cerebellum result in paralysis?
NO
What 2 components make up the corpus striatum?
Putamen
Caudate
What does the basal ganglia help with?
Learning and memory of complex motor behaviors
How you orient your body to do a movement
What do lesions in the basal ganglia result in?
Inability to learn a new motor activity or use one you have learned before
What is dyskinesia?
Motor movements that aren’t normal
Ex- shaking, abnormal gait, many different forms
Where is the lesion most likely when an individual has a tremor at rest but the tremor goes away when they make a movement?
lesion in basal ganglia
What part of the basal ganglia gives output of the striatum to the thalamus?
Globus pallidus
In Huntington’s disease, what part of the basal ganglia is destroyed?
Caudate nucleus
What is related to behavior function. When you have a certain emotion there is a particular position you assume.
Ventral striatum
What gives doapmine input to the caudate and putamen?
Substantia niagra
What disease causes you to lose dopamine receptors?
Parkinson’s Disease
Where do the function of the basal ganglia and cerebellum come together?
Thalamus
The basal ganglia regulate and integrate movements on the _______ side of the body?
Contralateral
What part of the basal ganglia is involved in retaining and applying patterns related to learned skill movements?
Putamen
What part of the basal ganglia controls sequencing and speed of movements and selection of appropriate movement pattern?
Caudate
What is ballismus?
Wild flinging movements of extremities
Lesions in the _______ lead to ballismus (usually only on one side of the body)
Subthalamic nucleus
Lesions in the caudate-putamen lead to what?
Corea- brisk movements of all extremities
What is a variant of chorea, but movements are slow and writhing?
Athetosis
What is a twisted movement where an individual is stuck in a position. Can do a movement but will always go back to that position.
Dystonia
What disease is caused by an injury to the basal ganglia during birth?
Cerebral palsy
What is hyperextended antigravity posture due to?
Vestibulospinal nuclei and tracts being unopposed (result of injury to basal ganglia)
A lesion in what type motor neuron will result in hyperreflexia?
Upper motor neuron
Lower motor neuron symptoms are ______?
Ipsilateral
A lesion in what type motor neuron will result in hyporeflexia?
Lower motor neuron lesion
What is ALS a disease of?
Lower motor neurons
What is the extensor-plantar reflex (Babinski reflex) due to?
Interruption of the corticospinal tract somewhere along it scourse
A lesion in what type motor neuron will result in a Babinski response?
Upper motor neuron
