Neurology I Flashcards
Neural plate development mechanism
Notochord induces overlying ectoderm to differentiate into neuroectoderm and form neural plate –> neural plate gives rise to neural tube and neural crest cells.
What are neural crest cells derived from?
Neural plate
Hindbrain gives rise to..
mesencephalon + myelencephalon
CNS embryology
Code: /forebrain telencephalon + diencephalon. Eagle with talons into cerebral hemispheres on wall on left + between two ventricles/telencephalon cerebral hemispheres + lateral ventricles. Pile of dice on wall on left + Kai thaler on sitting on top + aqueduct lined with ham/diencephalon thalamus + third ventricle. Meso soup on wall across + brain in the middle + aqueduct behind it lined with brains/mesencephalon midbrain + cerebral aqueduct. /hindbrain metencephalon + myelencephalon. Metropolitan museum of art in right corner + pond in front of it + bell hanging above pond + covered in hair/metencephalon pons and cerebellum + 4th ventricle. Mylo in front of hair covered aqueduct on wall on right + medusa head/myelencephalon medulla + 4th ventricle.
Location: Computer lab in library
What are microglia derived from?
mesoderm
Origin of CNS and PNS neurons
CNS neurons from neuroectoderm.
PNS neurons from neural crest
Neural tube area of codebook is basically…
neuroectoderm
What are ependymal cells derived from?
neuroectoderm
When do NTD’s usually happen?
4th week
Caveat about spina bifida occulta
AFP won’t be increased.
spina bifida occulta characteristics
1) dura intact
2) no herniation
What commonly herniates in meningomyelocele?
Cauda equina
Anencephaly findings
1) increased AFP
2) polyhydramnios (due to lack of swallowing center in brain).
Anencephaly association
maternal type I diabetes
Holoprosencephaly
♣ Coded character: /failure of left and right hemispheres to separate. 2 sharks at a table by window, hailing on one, other one sitting on a mound of hash/usually occurs during weeks 5-6. Erica emms is the waitress + has a clef lip + a Cyclops head/moderate form has cleft lip/palate, most severe form results in cyclopia.
♣ Location: right side of park burger
Chiari I malformation
o Code: kiara with a top hat on driving/Chiari I. /often diagnosed in adults and adolescents (less severe so less likely to present earlier). big mouth with inflamed tonsils on fairway + worm crawling out/Type I = significant herniation of cerebellar tonsils and vermis through foramen magnum. /more common but less severe than Chiari II. Nail through head + tape over mouth + antlers/presentation = headache and neck pain + lower brainstem symptoms (dysarthria + dysphagia + nystagmus). /can by asymptomatic.
o Location: Driving range at woodlands
arnold chiari malformation
♣ Coded character: huge mouth with tonsils hanging out + worm crawling out + medusa head on top/type II = tonsils + vermis + medulla herniate into the foramen magnum. Arnold Palmer: Roman aqueduct surrounding putting green/aqueductal stenosis. Arnold dancing around/mostly asymptomatic. Geiser of water coming out of his head + he’s on a stretcher (paralysis code) + huge sack hanging out of his lumbosacral region/presentation = hydrocephalus + lumbosacral meningomyelocele (this is what generates the pressure gradient and causes the herniation) + paralysis below level of defect. Siamese twin kiaras putting/Chiari II. He’s naked but wearing a cloak/syringomyelia is common.
♣ Location: Putting green at the woodlands
Enlargement of 4th ventricle…
Dandy-Walker syndrome
Dandy walker associations…
1) noncommunicating hydrocephalus
2) spina bifida
anterior white commissure part of…
Spinothalamic tract
syringomyelia causes
1) chiari malformations
2) trauma
3) tumors
Chiari 1 presentation
headaches + cerebellar symptoms
Most common location of syrinx
C8-T1
neuro loss with syringomyelia?
Bilateral loss of pain and temperature sensation with fine touch sensation preserved.
Tongue brachial arch origins
o Code: big tongue stuck ito ground with arch overhead. Hat on top + chicken nesting on top/anterior 2/3s of tongue is associated with pharyngeal arches 1 and 2. Hambone stuck into bottom/posterior 1/3 of tongue associated with pharyngeal arch 3.
o Location: patio outside St. Marks
Taste innervation of tongue
anterior - CN VII
posterior - IX, X (extreme posterior)
Pain innervation of tungue
anterior - V3
posterior - IX,X
hyoglossus action
retracts and depresses tognue
genioglossus action
protrudes tongue
syloglossus action
draws sides of tongue upward to create a trough for swallowing.
Motor innervation of tongue
1) CN XII to hyoglossus + genioglosus + sytloglossus
2) CN X to palatoglossus.
What does Nissl staining stain?
RER
What does Nissl staining pick up and not pick up?
1) cell bodies + dendrites
2) can’t stain axon (No RER) or microglia
Wallerian degeneration
Any injury to axon.
1) degenerates distal to injury
2) axon retracts proximally
Astrocyte functions
1) physical support
2) repair
3) K+ metabolism
4) removal of excess neurotransmitter
5) BBB
6) glycogen fuel reserve buffer
7) reactive gliosis in response to neural injury
Why does GFAP a marker of?
astrocytes
Microglia relevance to HIV
When infected by HIV, they fuse to form multinucleate giant cells.
Microglia function
Phagocytic, scavenger cells. Activated in response to tissue damage.
Myelin affects on nerves
1) increase space constant
2) increase conduction velocity
space constant
AKA length constant. Distance electric potential will travel along a neurite via passive electrical conduction.
Schwann cells and myelination
Each schwann cell myelinated only 1 PNS axon
Significance of nodes of Ranvier?
High concentration of Na channels
Guillain-Barre injury
damaged Schwann cells
typical location of vestibular schwannoma
internal acoustic meatus
Oligodendroglia and number of axons myelinate
many (around 30)
White vs. grey matter
1) Grey matter contains numerous cell bodies and relatively few myelinated axons.
2) White matter contains mostly myelinated axons. Myelin is white.
Predominant glial cell type in white matter?
Oligodendroglia
Histologic appearance of oligodendroglia?
Fried eggs
What is damaged in leukodystrophies?
oligodendroglia
Sensory neuron fiber type in free nerve endings?
C fibers and AlphaDelta fibers
Where are free nerve endings?
All skin + epidermis + some viscera
C fiber characteristics?
Slow, unmyelinated
Alphadelta fiber characters?
Fast, myelinated
C and Alphadelta fibers sense?
Pain temperature
Difference in sensitivity between C and Alphadelta fibers?
1) Alphadelta are faster so sense quick shallow pain specific to one area.
2) C fibers are slow and respond to stronger intensities, so deeper and more spread out stimuli.
Meissner corpuscles characteristics
Large, myelinated fibers; adapt quickly
Meissner corpuscles expressed in…
Glabrous (hairless) skin
Meissner corpuscles functions
1) dynamic touch
2) fine/light touch
3) position sense
Pacinian corpuscles characteristics
1) large, myelinated
2) adapt quickly
Pacinian corpuscles expressed in
Deep skin layers, ligaments, joints
Pacinian corpuscles sense
Vibration + pressure
Merkel discs characteristics
1) large, myelinated
2) adapt quickly
Merkel discs expressed in…
Finger tips + superficial skin
Merkel discs sense
1) pressure
2) deep static touch (eg shapes, edges)
3) position sense
Ruffini corpuscles characteristics
1) Dendritic endings with capsule
2) adapt slowly
Ruffini corpuscles expressed in
Finger tips + joints
Ruffini corpuscles functons
1) pressure
2) slippage of objects along surface of skin
3) joint angle change
endo vs peri vs epineurium
1) Endoneurium surrounds single nerve fiber
2) Perineurium surrounds fascicle of nerve fibers
3) Epineurium is dense connective tissue surrounding entire nerve and contains fascicles and blood vessels.
perineurium function
permeability barrier
Where is the inflammatory infiltrate found in Guillain-Barre?
Endoneurium
What needs to be rejoined in microsurgery for limb reattachment?
Perineurium
