Neuro Flashcards
cells that line the ventricles & central canal of spinal cord, are ciliated and direct flow of CSF
ependymal cells
derived from neuroectoderm
embryonic derivation of peripheral nervous system structures: DRG, cranial nerves, melanocytes, chromaffin cells (adrenal medulla), C cells of thyroid, odontoblasts, pia & arachnoid
neural crest
Not CNS but PNS
midline sulcus of the pons contains what?
basilar artery
cranial nerves that exit the midbrain
CN III and IV
connects the two hemispheres of the brain
corpus callosum
comprise the striatum
caudate nucleus & putamen
bridge that connects them is the nucleus accumbens
responsible for the emotional significance of experiences
amygdala
Note: seizures involving the amygdala cause powerful emotions of fear and panic
surrounds the third ventricle
thalamus
connects the third and fourth ventricles
cerebral aqueduct
channel between the lateral ventricles and third ventricle
foramen of Munro (interventricular foramen)
produces CSF
choroid plexus
spatial awareness of surroundings, taste, somatosensation
parietal lobe
hearing, language comprehension (Wernicke’s area), object and face recognition
temporal lobe
vision, visual spacial awareness, color perception
occipital lobe
movement (primary motor), speech (Broca’s area), motor association cortex
frontal lobe
dominant hemisphere -> speech comprehension and production
left hemisphere
bilateral damage to the amygdala producing the inability to perceive situations as dangerous other features: -visual agnosia -place objects in mouth -increased sexual behavior -decreased facial expressions
Kluver-Bucy syndrome
long-term memory
hippocampus
caudate nucleus, putamen, and globus pallidus
basal ganglia
function: initiation and maintenance of actions
damage to basal ganglia results in movement disorders
suspicious for neural tube defects
elevated AFP in amniotic fluid and maternal serum
elevated AChE in amniotic fluid
failure of bony spinal canal to close
intact dura
tuft of hair or dimple
spina bifida occulta
meninges herniate through spinal canal defect
AFP normal
meningocele
meninges and spinal cord herniate through spinal canal defect
meningomyelocele
no forebrain
open calvarium -> looks “frog-like”
elevated AFP
polyhydramnios
anencephaly
associated with maternal type 1 DM
herniation of cerebellar tonsils through foramen magnum
aqueductal stenosis
paralysis below defect
Arnold-Chiari malformation (Chiari II)
parts of cerebellar vermis develop abnormally
hydrocephalus & macrocephaly within first year
delayed: crawling, walking, coordinated movements
cystic enlargement of 4th ventricle
Dandy-Walker
- cystic cavity within spinal cord
- capelike bilateral loss of pain and temperature sensation in the upper extremities
- preservation of fine touch
- most common at C8-T1
syringomyelia
Associated with Chiari I malformation (headaches & cerebellar symptoms in presentation but usually asymptomatic in childhood)
syrinx in the central canal
hydromyelia
motor innervation of the tongue
CN XII
taste and sensation innervation of the tongue
Taste: CN VII (ant), CN IX (post)
Sensation: V3 (ant), CN IX (post)
degeneration of axon distal to injury and axonal retraction proximally
Wallerian degeneration
Group of infections transmitted from the mother to the fetus with similar clinical manifestations.
Involves skin, heart, eye, CNS & causes chorioretinitis
TORCH complex: Toxoplasma Rubella CMV Herpes
GFAP
astrocyte marker
phagocytes of CNS that are scavenger cells; when activated these become antigen-presenting cells and produce cytokines
microglia
physical support cells of CNS
- repair
- potassium metabolism
- remove excess NT
- component of BBB
- glycogen fuel reserve
- perform reactive gliosis in response to injury (scar tissue)
astrocytes
produce myelin in the CNS; can myelinate several axons
oligodendrocytes
produce myelin in the PNS; myelinates a single axon
Schwann cells
Where are there high concentrations of sodium channels?
nodes of Ranvier
derived from neuroectoderm
- astrocytes
2. oligodendrocytes
derived from mesoderm
microglia
derived from neural crest
schwann cells
injured in multiple sclerosis, PML, & leukodystrophies
oligodendocytes
destroyed in Guillain-Barre
schwann cells
myelinated fibers that sense Pressure & Vibration
- deep skin layers
- ligaments
- joints
Pacinian corpuscles
Pacinian = Pressure
myelinated fibers in hairless skin
dynamic, fine/light touch
position sense
Meissner corpuscles
myelinated fibers in basal epidermal layer & hair follicles
Senses pressure, deep static touch, position sense
Merkel discs
direct outgrowth of the hypothalamus
posterior pituitary
regulates:
- sleep-wake cycles
- thermoregulation
- fluid intake
- growth
- metabolic energy expenditure
- reproduction
hypothalamus
hypothalamic nucleus that controls circadian rhythms via connections with the pineal gland
suprachiasmatic nucleus
“you need to sleep to be charismatic”
thirst centers nucleus
supraoptic nucleus
divisions of the Peripheral Nervous System
- somatic nervous system
2. autonomic nervous system
hemisection of spinal cord resulting in ipsilateral loss of sensation and voluntary muscle movement at level of the injury (stab or gunshot); ipsilateral spastic paresis below level of lesion; ipsilateral loss of light touch, vibration & proprioception below level of lesion; contralateral loss of pain & temperature below level of the lesion
Brown-Sequard syndrome
Mean Arterial Pressure - ICP
Cerebral Perfusion Pressure
metabolic mechanisms regulate arteriole size to maintain constant cerebral blood flow over a pressure range of 60-150 mm Hg
autoregulation
cause increased cerebral blood flow
hypoxia
hypercarbia
decreases cerebral blood flow
hypocarbia
causes cerebral vasoconstriction
How does too much oxygen produce deleterious effects on brain cells?
formation of free radicals
oxidation of NTs
major cerebral branches of the internal carotid arteries
MCA & ACA
These supply 80% of blood to the brain.
MCA receives 80% of carotid blood flow
Which arteries supply the spinal cord? From what arteries?
Anterior and Posterior spinal arteries.
Branches of Vertebral arteries which branch from the brachiocephalic (on R) and subclavian (on L)
Functional areas of the posterior cerebral arteries
- Visual cortex
- hippocampus
- thalamus
- hypothalamus
most important cause of ischemic stroke
atherosclerosis
most common site for hypertensive intracerebral hemorrhage
basal ganglia
mechanisms of brain death in ischemia
excitotoxicity, inflammation, programmed cell death
brain hypoxia -> decreased ATP -> Na+ pumps fail -> sodium enters cell -> depolarization -> more sodium influx & water = edema
-extracellular K+ rise causes depolarization ->glutamate release -> activation of NMDA receptor -> calcium influx -> free radical generation & apoptosis pathway activation
hyperreflexia
spasticity
positive Babinski
upper motor neuron damage
Note: + Babinski is normal in children up to age 2 yr
Which cranial nerve? shrug shoulders or turn face to each side against resistance
CN XI
ATPases which are motor molecules for anterograde transport
kinesin and kinesin-related proteins
positive membrane potential
depolarization
membrane potential that is more negative
hyperpolarization
What produces neuronal resting membrane potential?
continual efflux of K+
The membrane is only permeable to potassium under normal resting conditions. It becomes transiently permeable to sodium during rising phase and overshoot phase of action potential.
What causes papilledema?
increased ICP
What prevents backward propagation of the action potential?
inactivation of sodium channels = refractory period
- two or more deficits separated in neuroanatomical space and time
- autoimmune inflammation & demyelination of brain & spinal cord while sparing PNS
- white matter lesions
- oligoclonal bands in CSF**
- MRI is gold standard
- Marcus Gunn pupils
- nystagmus
Multiple sclerosis Presentation: -female: age 20-30 -vision loss -internuclear ophthalmoplegia -hemiparesis -bladder/bowel incontinence -relapsing/remitting
- autoimmune destruction of Schwann cells triggered by Campylobacter jejuni & CMV
- molecular mimicry
- symmetric ascending weakness/paralysis
- majority recover completely after weeks or months
Guillain Barre
Acute Inflammatory demyelinating polyradiculopathy
virus that infects and kills oligodendrocytes, causing demyelination
associated with immunocompromised (10% AIDS pts)
Causes progressive multifocal leukoencephalopathy PML)
virus replicates in the epithelial cells of the capillaries
JC virus
reward nucleus
nucleus accumbens
slow progressive demyelination in CNS ending in death
Persistence of defective measles virus in brain
most prevalent in children who were infected before age 2
lack of M component of measles virus, which is required for extracellular spread -> slow infection -> no anti-M antibodies present
monoclonic jerks, blindness, spasticity
Subacute Sclerosing Panencephalitis (SSPE)
California encephalitis virus spread by mosquitos
reservoir: chipmunk or squirrel
seizures in 50%
LaCrosse Virus
amyloid plaques in CNS
PrP resistant to degradation -> no DNA or RNA
small cysts in gray matter with absence of inflammatory response
long incubation period
progressive dementia, ataxia, myoclonus & death in 5-12months
Host is cattle
Creutzfeldt-Jakob disease
spongiform encephalopathies
Note: CJD can be transmitted by corneal transplant
anterograde amnesia vs retrograde amnesia
anterograde: inability to make new memories after neuro insult
retrograde: inability to retrieve memories prior to neuro insult
Forms BBB
- tight junctions of capillary endothelial cells
- basement membrane
- astrocyte foot processes
region of the hypothalamus that stimulates appetite
lateral
“I have to go out laterally to find food when I’m hungry”
area of the hypothalamus that dissipates heat
anterior
the posterior conserves heat -> “hot posterior!”
functions of limbic system: HOME
Homeostatic functions -> autonomic & neuroendocrine
Olfaction
Memory
Emotions and drives
nucleus that contains the major cholinergic innervation of the cerebral cortex
nucleus basalis
What lobe contains the amygdala?
temporal
loss of emotional expression in speech
aprosodia
Emotion is lateralized to the right hemisphere
contains medium spiny neurons that modulate the influence of dopamine
nucleus accumbens
Receives projections from the ventral tegmental area (VTA)
which hemisphere is involved in attention to both sides of the body?
Right (typically parietal lobe)
lesion to the right hemisphere can result in Left hemineglect.
areas not protected by the BBB
OVLT
area postrema
motor deficit
apraxis
area for planning, control and execution of actions
personality
Frontal Association Cortex
term and area for difficulty recognizing and NAMING objects
agnosia -> mismatch of verbal or cognitive symbols with sensory stimuli
temporal association cortex
inability to recognize and identify faces
prosopagnosia
What is thought to be defective in understanding the intentions of others by a child with autism?
mirror neurons
separates the outer ear from the middle ear
tympanic membrane
muscles that move the malleus, incus & stapes
tensor tympani (trigeminal nerve) tensor stapedius (facial nerve)
part of the ear involved in balance
vestibular apparatus
Balance receptors are located within the semicircular canals & vestibule
auditory receptor organ
organ of Corti
has hair cells with stereocilia
main auditory nucleus of the thalamus
medial geniculate nucleus
The inferior colliculus projects to this
inability to carry out an action in response to a verbal command
apraxia
nonfluent effortful speech
right hemiparesis
comprehends language (simple)
Broca’s aphasia
fluent speech but nonsense
impaired comprehension
Wernicke’s aphasia
inability to understand written words
alexia
crossed eyes
esotropia
wall eyes
exotropia
two eyes cannot be aligned
strabismus
critical period for language
0-12 years
children can speak a second language with fluent grammar until age 7-8 yr
unilateral hearing loss indicates
damage to the ipsilateral nerve or ear
damage to the cortex or thalamus presents as poor speech discrimination, poor sound localization, poor selective attention
in newborns: hydrocephalus, mental retardation
on radiograph: periventricular calcifications
Sites of involvement: cortex, basal ganglia, retinae, heart, lungs & liver
mom ingested food contaminated by animal urine or feces
Toxoplasmosis
infection of the meninges
fever, headache, nuchal rigidity
CSF: increased lymphocytes, mod increased protein, normal glucose
VIRAL meningitis
Degeneration and necrosis of anterior horn cells or spinal cord
fecal-oral transmission
replicates in oropharynx and small intestine
hematogenous spread
Presents with weakness, hypotonia, flaccid paralysis, fasciculations, hyporeflexia, muscle atrophy
poliomyelitis
CSF: increased protein, increased WBCs, normal glucose
AD
numerous benign neuromas & optic nerve gliomas
neuromas can develop later into malignant peripheral nerve sheath tumors
mutation of NF1 (encodes neurofibromin -> loss results in active RAS signaling -> expressed in all tissues but especially brain, spinal cord and PNS)
“two hit” hypothesis
neurofibromatosis 1
• Criteria for diagnosis of NF1 (need at least 2)
○ Six or more café au lait spots measuring 5 mm in diameter prepubertal or 15 mm postpubertal
○ Two or more neurofibromas of any type
○ One plexiform neurofibroma
○ Axillary of inguinal freckling
○ Optic glioma
○ 2 or more Lisch nodules
○ Sphenoid dysplasia or thinning of long bone cortex with or without pseudoarthrosis
○ First-degree relative with NF1
AD
bilateral benign schwannomas of the acoustic nerve
protein product of mutant allele is merlin
NF2
○ Develops at 6 months age
○ Affected children become blind and regress mentally and physically
○ Fatal in early childhood (2-4 years)
○ Motor development plateaus and regresses at 8 months; loss of voluntary movement by age 2
-Causes a deficiency of hexosaminidase A, an enzyme required for catabolism of GM2 ganglioside
AR
Tay-Sachs
Ashkenazi Jewish population
degeneration of dorsal columns and roots impaired sensation & proprioception progressive sensory ataxia Charcot joints, shooting pains Argyll Robertson pupils Absence of DTRs \+ Romberg
Tabes dorsalis
Tertiary syphilis
weakness atrophy fasciculations flaccid paralysis diminished reflexes and muscle tone
LMN lesion
weakness Babinski spastic paralysis clasp knife spasticity increased reflexes and muscle tone
UMN lesion
ascending: pressure, vibration, fine touch, proprioception
Dorsal column
ipsilateral dorsal column -> nucleus cuneatus or gracilis in medulla -> decussates and ascends in the medial lemniscus -> VPL in thalamus to sensory cortex
portion of the dorsal column for lower body/legs
Fasciculus gracilis
portion of the dorsal column for upper body and arms
Fasciculus cuneatus
Lateral: Pain, temperature
Anterior: Crude touch, pressure
Spinothalamic tract
sensory nerve -> ipsilateral gray matter of spinal cord -> decussates anterior white commissure -> contralateral ascends -> VPL thalamus
descending: voluntary movement of contralateral limb
lateral corticospinal tract
- combined UMN & LMN defects with no sensory, cognitive or oculomotor defects
- defect in SOD1
- fasciculations with atrophy and weakness of hands
- fatal
amyotrophic lateral sclerosis
tx: riluzole
level where the spinal cord ends
L1-L2 in the adult
Lumbar puncture is performed between L3-L4 or L4-L5
AR kyphoscoliosis in childhood GAA repeat -> frataxin -> iron metabolism muscle weakness & loss of DTRs, vibratory sense, proprioception Staggering gait Frequent falls nystagmus hammer toes hypertrophic cardiomyopathy
Friedreich ataxia
○ Onset: typically before adolescence and characterized by incoordination of limb movements, difficulty with speech, diminished or absent tendon reflexes, impairment of position and vibratory senses, cardiomyopathy, scoliosis, foot deformities , type 2 diabetes
Ptosis
Anhidrosis
Miosis
associated with lesion of spinal cord above T1: Pancoast tumor, Brown-Sequard, late-stage syringomyelia
Horner syndrome
sympathetic loss of the face
levels of nipple and umbilicus
level of the penis
nipple T4 teat pore at T4
umbilicus T10 is at belly butTEN”
penis: S2-S4 “S2, 3, 4 keep the penis off the floor”
colliculus corresponding functions
superior?
inferior?
superior colliculus: conjugate vertical gaze
inferior colliculus: auditory
“your eyes are above your ears”
corneal reflex
afferent CN? efferent CN?
afferent: V1 (ophthalmic)
efferent: VII (temporal branch)
lacrimation
Afferent CN?
Efferent CN?
A: V1
E: VII
jaw jerk reflex
Afferent CN?
Efferent CN?
A: V3 sensory
E: V3 motor
Pupillary reflex
Afferent CN?
Efferent CN?
A: II
E: III
Gag reflex
Afferent?
Efferent?
A: IX
E: X
produces aqueous humor
ciliary processes of the posterior chamber
gelatinous substance between the back of the lens and retina
Maintains the shape of the eye
vitreous humor
Why does increased ICP make the optic disk swell (papilledema)?
the subarachnoid space surrounding the optic nerve is continuous with the subarachnoid space of the brain. Increased ICP will make the optic disk swell.
Changes the shape of the lens for focusing
ciliary muscles
produced by the ciliary body and flows through the pupil to the anterior chamber to provide nutrients to the cornea & lens
aqueous humor
this drains into the venous blood via the canal of Schlemm. Blockage of the canal of Schlemm leads to glaucoma.
crystallin proteins become oxidized and aggregate, usually due to older age
cataract
Complication of measles.
Lethal changes in personality, behavior, memory, myoclonic jerks, blindness and spasticity
Subacute sclerosing panencephalitis
Location where CN III, CN IV and CN VI enter the orbit of the eye
Superior orbital fissure
