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126 Cards in this Set
- Front
- Back
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What is Grey Matter?
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Neuron Cell Bodies
Dendrites Synapses Axons (also contains glial cells and blood vessels) |
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What is white matter?
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mylinated tracts
(also contains glial cells and blood vessels) |
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What are the three "avenues" (long tracts & Pathways)
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Sensory: Pain/Temp vs. Proprioception/Vibration
Motor: Descending pyramidal tracts Coordination: pathways to and from the Cerebellum |
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What are the three "streets" in the Brain (horizontal/exiting pathways)
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Cerebral: cortical functions; homunculus
Brainstem: exiting cranial nerves define level Cord: exiting roots (dermatomes) define level |
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Anterior part of the brain controls?
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Motor
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What is at the precentral gyrus
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Primary motor cortex
(NO PLURIPOTENT CELLS) |
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What is at the postcentral gyrus
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Primary sensory cortex
(NO PLURIPOTENT CELLS) |
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What is aphasia, what hemisphere is dominant? and What are two types of aphasia?
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Aphasia is focal disturbances of language. Dominant hemisphere is usually the left. 2 Forms:
Broca's (Frontal): Motor/expressive - ergo cannot make language WErnicke's (posterior): sensory/receptive - cannot understand language |
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What is Sensory Neglect? What side is it on?
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It is focal disturbances of "sensory integration"... ergo you are unable to perceive a stimulus despite intact sensory pathways, "left hemineglect" (only draw half a clock) it affects the non-dominant hemisphere usually right)
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What is Visual Agnosias
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Unable to interpret that which you see "the man who mistook his wife for a hat" --> effects the occipital lobe
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Frontal Lobe Dysfunction?
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Behavior Syndromes:
Disinhibited, lewd, loud (See Mr. Gage, below) Poor planning, impaired complex thinking Flattened affect; motionless; “lobotomized” |
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Name three types of Glial cells
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Astrocytes
Oligodendrocytes Ependymal cells |
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What stain is used to see lipids (to see neurons)
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BIELSCHOWSKY STAIN
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What is a glial scar and what is it composed of?
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Glial scar is composed of reactive astrocytes.
Gliosis – the deposition of glial fibers (glial fibrillary acidic protein, GFAP) by astrocytes, a form of scar formation in the brain |
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Are the peripheral nerves and roots considered part of the CNS or PNS?
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PNS
(peripheral nervous system) |
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Where does zoster reactivate from?
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DORSAL ROOT GANGLIA
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What is a radiculopathy?
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Involvement of Nerves
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Name two diseases that "mimic" motor radiculopathies?
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ALS & Polio
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LMN symptoms
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marked atrophy
limbs are held in a flaccid posture Fasciculations loss of bulk, much loss of strength (pattern will tell you whether it is generalized, or limited to a single root) Dropped reflexes (areflexia) |
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UMN
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Rigid, spastic
Clonus hyperreflexia Babvinsky sign |
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What is
T5 T10 T8 L1 L5 S1 |
T5 - Nipple
T10 - UMBILICUS (Belly button) T8 - Costal Margin L1 - inguinal crease L5 - big toe S1 - sole of foot |
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CT scanning advantages
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Rapid (<sec)
Less patient cooperation LIfe support devices are okay in them Sensitive HEMORRHAGE detection Low radiation dose |
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How is intensity increased in the somatosensory pathway?
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increased number of action potential which leads to increased axons recruited
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When and how long do rapidly adapting neurons fire
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good at telling when things go on, when they go off and when things change
Don't continue... |
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Slow adapting neurons fire when?
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fire the ENTIRE time the stimulus is applied
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Where is the receptive field bigger? Finger or back?
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Back - not as sensitive to detect different stimuli
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What cutaneous neurons control Pain, crude touch, & Temperature
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alpha delta & C fibers
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Which cutaneous neurons control touch and pressure
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AB
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What muscle groups are fast and large conductors?
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I& II
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What muscle nerve groups control pain and temp
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III&IV
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What is the DC-ML system for?
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Dorsal Column Medial Lemniscus is for mechanosensation
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What is the Anteriolateral (spinothalamic tract system for)
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Pain & temperature
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What is Brown Sequard Syndrome?
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Brown-Séquard syndrome is an incomplete spinal cord lesion characterized by findings on clinical examination which reflect hemisection of the spinal cord (cutting the spinal cord in half on one or the other side). It is diagnosed by finding motor (muscle) paralysis on the same (ipsilateral) side as the lesion and deficits in pain and temperature sensation on the opposite (contralateral) side.
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What tract does pain and temp travel up?
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Lateral spinothalamic tract
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In the mid -medulla, what is more ventral? Legs or Neck?
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Legs
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In the midbrain what is more ventral? Legs or face
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Face
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In the mid upper pons, what is more medial - legs or face?
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Face
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Where is the spinothalamic tract in the spinal cord?
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Below each of the ventral horns
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Where is the spinothalamic tract in the Medulla?
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Above the Olives lateral to the center where the medial lemniscus is
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Where is the spinothalamic tract in the Midbrain
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Dorsal end; lateral
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Where does the principle trigeminal nucleus enter the thalamus (medial or lateral)
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VPM
Ventral Posterior Medial |
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Where do the dorsal nuclei (body, neck, back of head) enter the thalamus? (medial or lateral?)
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VPL
Ventral Posterior Lateral |
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Which system is has somatotropic organization? spinothalamic system or dorsal column - medial Lemniscus system?
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DCML system
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Which system is has large receptive fields? spinothalamic system or dorsal column - medial Lemniscus system?
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Spinothalamic System
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What subfields of S1 (primary sensory gyrus) are for proprioception?
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3a &2
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What subfields of S1 (primary sensory gyrus) are for cutaneous (touch)?
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3B&1
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What subfields of S1 (primary sensory gyrus) are for pain and temp?
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All of them: 1, 2, 3a, 3b
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What initiates movement?
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Basal Ganglia
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What is involved in coordination and timing of movement?
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Cerebellum
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Upper motor neurons are from what portions of the brain?
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cerebellum & basal ganglia
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What are the three principle sources of input that converge on the motor neurons
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The supraspinal or descending motor pathways.
Spinal neurons (segmental interneurons and intersegmental neurons). Primary afferent (sensory) fibers. |
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How does the upper motor neurons influence the lower motor neurons?
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**They SELDOM directly connect, but rather they influence via a network of local circuit neurons
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Role of Primary Motor Cortex (M1)
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Directs movement
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Role of Medial premotor area (M2)
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initiates movements specified by INTERNAL cues, i.e. spontaneous movements.
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Role of lateral premotor area (PM)
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selects movements based on EXTERNAL cues, i.e. events or context.
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Cingulate motor area (M3)
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selects movements based on emotional state or reward information.
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What type of Neurons and which lamina are located in the Dorsal Horn of the Spinal cord?
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Sensory Neurons
Lamina I-VI |
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What types of neurons and what lamina are located in the Intermediate zone of the spinal cord?
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terminations of descending and sensory neurons; upper portion of lamina VII
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What types of neurons and what lamina are located in the VENTRAL HORN of the spinal cord?
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interneurons and motor neurons; lower portion of lamina VII, and laminae VIII and IX
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What Lamina are the motor neurons localized to?
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IX in the motor nuclear columns
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Where are flexor muscles represented on the spinal cord?
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Dorsal
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Where are extensor muscles represented on the spinal cord?
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Ventrally
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Where are distal muscles represented on the spinal cord
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laterally
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Where are proximal muscles represented on the spinal cord?
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Medially
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What happens if muscle groups on either side of a joint contract at the same time?
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The joint becomes locked & no movement
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What are Cerebral cortical motor areas involved in?
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Voluntary motor behavior as well as in modulating (through brainstem pathways) postural and reflex motor patterns.
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What are Cortical motor areas involved in?
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Integrate information from somatosensory areas and visual and auditory association areas of the parietal and temporal lobes.
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Name the 4 corticomotor areas?
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1) Primary Motor Cortex (M1)
2) Supplementary Motor Area (M2) 3) Lateral premotor cortex (PM) 4) Cingulate motor area (M3) |
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Does the Corticol motor areas have a large or low threshold of excitability
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Low!
Which is indicative of the large and direct pathway from this area to the lower motor neurons in the brainstem and spinal cord. |
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Where does the UMN receive inputs from?
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Thalamus; which receives inputs from the basal ganglia and the cerebellum
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How can Corticomotor areas DIRECTLY influence spinal cord or cranial motor nuclei?
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Via the corticospinal tract;
(usually its indirectly) |
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How can Corticomotor areas INDIRECTLY influence spinal cord or cranial motor nuclei?
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Via the descending brainstem projections
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Large Beltz cells
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These are involved with ballistic, bidirectional movements; they show all or none firing and are uninfluenced by sensory feedback. They constitute approx. 10% of the pyramidal tract axons.
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Small Pyramidal cells
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These are involved with slow, accurate, controlled, unidirectional movements, and are under tight somatic sensory control. They show graded firing proportional to the force exerted. These constitute 90% of the pyramidal tract axons.
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corticomotoneuronal (CM) cells
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Corticospinal neurons from M1 that can synapse directly (monosynaptically) onto spinal motoneurons
--> usually innervate distal muscles (ex intrinsic muscles of hand) *minority of corticospinal neurons |
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Where doe the majority of corticospinal neurons synapse?
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On INTERNEURONS
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M1 LESIONS?
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Cause loss of fine motor skills (i.e. independent finger movements)
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What are high order cortical motor areas?
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supplementary motor area (M2)
lateral premotor cortex (PM) cingulate motor area (M3) eceive strong inputs from other higher-order cortical association areas, particularly somatosensory areas (i.e. information concerning extrapersonal space) and visual and auditory assoociation cortices via converging corticocortical inputs. * also receive heavy input from basal ganglia via thalamus |
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Do higher order cortical motor areas directly project on the spinal cord?
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Yes, via the corticospinal tract.
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SMA (M2) role
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planning and initiating self-generated movements.
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M2 lesions
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cause impairment in planning "self-initiated" motor tasks, esp bimanual (ex manipulating the fingers of both hands in order to button a shirt)
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The lateral premotor cortex (PM)
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It is important in planning and initiating movements that are sensory-guided (or externally-cued).
Contralateral... example: reaching for a target in extra-personal space based on visual or auditory cues which dictate the upcoming movement. |
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PM lesions
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apraxias.
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The cingulate motor area
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process reward information for motor selection...
Contains motor neurons of facial motor nucleus that innervate UPPER half of the face --> -->blood is from ANTERIOR cerebral artery (ergo spared in people w/ stroke of middle cerebral artery) |
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Where does the corticospinal tract primary descending pathway travel through?
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1) posterior limb of the internal capsule
2) the cerebral peduncle 3) the basis pontis 4) Ipsilateral medullary pyramid. |
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What percent of fibers from the corticospinal tract cross at the pyramidal decussation in the lower medulla?
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80%
20% are ipsilateral and form anterior corticospinal tract ; situated medially in spinal cord in white matter... |
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What do Direct monosynaptic connections control?
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Very fine movements such as movement btw fingers
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What is a motor unit?
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A motor neuron and all of the muscle fibers to which it connects
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Which motor neuron covers more muscle fibers - those to the finger or those to the back?
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That to the back -
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Which motor unit is activated first? Small or Large
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Small motor units are recruited first, followed by large ones. This is the size principle of motor neuron recruitment.
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Extrafusal Muscle Fibers
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force-generating
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Intrafusal
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no direct role in force generation, but rather are part of the muscle spindle.
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What type of neuron innervates extrafusal muscle fibers
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Alpha motor neurons
*alpha innervates force-generating muscle fibers |
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What type of neuron innervates intrafusal fibers?
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Gamma (or fusimotor) motor neurons
-->innervates muscle spindles which are stretch receptors and monitor changes in muscle length. |
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What are the two functional regions of a muscle spindle?
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1) Polar regions: composed of intrafusal muscle fibers and are contractile. They receive motor innervation from gamma-motoneurons.
2)equatorial region: non-contractile and receives sensory innervation from Group Ia and Group II sensory afferent fibers. |
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Which motor neurons control sensitivity of the spindle?
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GAMMA MOTORNEUONS
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Hemiplegic Gait - what does it look like and what causes it?
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*Arm is held in flexion with marked weakness of extensors of fingers, wrist and shoulder
*Hand and fingers tightly clenched with increased tone *There is specific weakness of hip flexion and ankle dorsiflexion a pattern known as “UMN weakness” *There is a swinging outwards of the leg There is hyperreflexia, clonus and upgoing plantar response |
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What is key thing to look for histologically when looking at strokes
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Hyper eosinophilic --> indicates dead cells and will be cleared by the body and become a glial scar
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How long does damage have to occur before see eosinophilia?
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6 hours (ergo if see it,know the person has been alive over 6 hours)
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What is cytotoxic edema?
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maintain normal osmotic pressures within the cells and they take on too much fluid – toxic to the cells; not fluid w/in the space between the cells, but the the cells themselves!!!
--> CANNOT USE MANNITOL (b/c its intracellular not extracellular swelling) |
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What cells phagocytose debri in the brain?
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Microglial cells
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What cells form the glial scar?
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Astrocytes!
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Where would you get a pure motor infarct?
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Internal capsule (posterior) or Pons lacunar (only at the pyramids of the pons)
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What percent of cardiac output goes to the brain?
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20%
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If get a "shower" of emboli with bilateral inracts, what is the most likely source of the emboli?
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Heart
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What do you see histologically in berry aneurysm?
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Lack of lamina!
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Are anneurysms more common in anterior or posterior circulation?
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Anterior (85% vs 15% posterior)
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What is a surgical third palsy?
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Surgical third nerve palsy is characterized by a sudden onset of unilateral ptosis and an enlarged or sluggish pupil to the light.
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What are common characteristics of Basilar Artery Aneurysms?
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Slow growing
Not subject to rupture Acts as a mass lesion |
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What is an Arterioveinous Malformation?
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A developmental abnormality with arteries emptying directly into veins without an intervening capillary bed
Recurits more and more blood vessels like a tumor |
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Why does blood show up as white on CT scan?
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b/c of its iron!
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What is an uncal herniation?
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a common subtype of transtentorial herniation, the innermost part of the temporal lobe, the uncus, can be squeezed so much that it goes by the tentorium and puts pressure on the brainstem, most notably the midbrain
---> part of cerebrum goes through tentorial notch into cerebellar area... --> causes 2ndary brainstem hemorrhage |
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Are regional infarcts involving the middle cerebral artery more often hemorrhagic or ischemic?
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Ischemic
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What is a common cause of hemorrhage into the subarachnoid space?
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Berry aneurysm
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What type of stroke is more common? Ischemic or Hemorrhagic?
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Ischemic (80%)
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What are immediate steps you take when someone has a stroke?
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ABC
Blood sugar (consider giving thiamine here as you don’t yet know it is a structural lesion) Glasgow Coma Scale Look for fever, neck stiffness Oxygen, IV access early! RAPID neuroexam:motor, speech,visual, sensory |
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True or false: Neuroimmagining is the only way to tell if stroke is hemorrhagic or ischemic
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True!
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What artery supplies the genu of corpus callousum?
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Anterior Cerebral artery
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What are signs of a dominant MCA stroke?
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Dense hemiplegia
With cortical localizing signs-aphasia, field cut |
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Weber's Syndrome
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is a form of stroke characterized by the presence of an oculomotor nerve palsy and contralateral hemiparesis or hemiplegia.
--> occlusion of branches of the PCA --> Know its in the Medulla b/c wiped out 3rd cranial nerve |
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Pyramids carry what sort of fibers?
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Motor!
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What cranial nerves come from the medulla?
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Lower 4: IX,X,XI,XII
--> if lesion in 12, tongue moves toward side of lesion |
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What is locked in syndrome?
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Complete stroke of the pons; only thing left is vertical eye gaze.
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Strokes involving PCA and Vertebrobasilar system are often from?
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The heart!!
Also consider verterbral dissection |
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What is a renshaw cell?
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Renshaw cells are spinal inhibitory interneurons --> inhibit original alpha neuron so doesn't continually fire
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What is Uhthoff’s phenomenon ?
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Sudden onset of neuorlogic symptoms in MS set off by high temperatures...
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