Neurology Flashcards Preview

USMLE > Neurology > Flashcards

Flashcards in Neurology Deck (176)
Loading flashcards...
1

Neural tube development

1) Notochord induces ectoderm to differentiate into neuroectoderm and form neural plate
2) Neural plate gives rise to neural tube and neural crest cells
3) Notochord becomes nucleus pulposus of intervertbral disc

Alar plate- dorsal, sensory
Basal plate- ventral, motor

2

Regionalization of the brain

PRimary vesicles: prosencephalon (forebrain), mesencephalon (midbrain), rhombencephalon (hindbrain)

Secondary vescles
-prosencephalon -- telencephalon (cerebral hemispheres and lateral venticles) and diencephalon (thalamus and third ventricle)
-mesencephalon -- midbrain and cerebral aqueduct
rhombencephalon --metencephalon (pons and cerebellum) and myelencephalon (medulla); both contribute to fourth ventricle

3

Neuroectoderm derivatives

CNS neurons, epednymal cells that line the ventricles and make CSF, oligodendroglia, astrocytes

4

Neural crest derivatives

PNS neurons and schwann cells

5

mesoderm derivatives

microglia (hematopoietic lineage)

6

Testing for neural tube defects

Elevated AFP in maternal serum and amniotic fliud
Elevated AChE in amniotic fluid

7

Spina bifida occulta

Failure of bony spinal canal to close without any structural herniation and with dura intact. AFP is normal. Least severe neural tube defect.

8

Meningocele and Meningomyelocele

Meningocele: meninges only herniate through bony defect
Meningomyelocele: meninges and nural tissue hernate through bony defect; associated with chiari II malformation

both have risk of ascending infection
Look like plaquode on skin

9

Holoprosencephaly

Not a neural tube defect. Failure of left and right hemispheres to separate. Can be caused by sonic hedgehog mutations. Associated with Patau syndrome and FAS. Associated with cleft palate/lip, cyclopia

10

Chiari II

Hernation of cerebellar tonsils and vermis through foramen magnum. Aqueductal sternosis and hydrocephalus as result. Meningomyelocele (neural tube defect) is associatd

11

Dandy Walker malformation

Agenesis of cerebellar vermis with cystic enlargement of the fourth ventricle. Associated with hydrocephalus and spina bifida

12

Syringomyelia

Cystic cavity in spinal cord. Typicall damages corssing anterior spinal commisurral fibers leading to cape like loss of pain and temp in upper extremities. Associated with chiari I

13

Chiari I malformation

Cerebellar tonsils herniate. Associated with syringomyelia. Usually asymptomatic in childhood

14

Tongue development

1st and second branchial arches: anterior 2/3 with sensation from V3, taste from VII
3rd and 4th arches form posterior 1/3 with sensation and taste from IX and X
Motor from X (palatoglossus) and XII (all others)

15

Nissl stain

Stains RER and can be used to visualize cell bodies and dendrites of neurons. Doesn't stain axon as RER is not present: proteins are synthesized in the cell body and transported down the axon

16

Wallerian degeneration

In response to axonal injury, the nerve degenerates distal to the injury and the axon retracts proximally, allowing for regeneration if in the PNS. Regeneration occurs slowly over weeks to months.

17

Astrocytes

Functions: physical support, repair, potassium metabolism, removal of excess neurotransmitter (take up glutamate and convert to glutamine), component of BBB, reactive gliosis in response to neuronal injury, match cerebral blood flow to synaptic activity

Marker: GFAP

Derivative of neuroectoderm

18

HIV in the brain

Infect microglia, which fuse to form multinucleated giant cells in the CNS

19

Scwann cells

Each Schwann cell myelinates 1 PNS axon. Promote axonal regeneration. Derived from neural crest

20

Oligodendroglia

Myelinate axons of CNS. Each oligodendrocyte can myelinate many axons. Derived from neuroectoderm. Fried egg appearance

21

Types of sensory receptors: free nerve endings, meissner corpuscles, pacinian corpuscles, merkel discs, ruffini corpuscles

Free nerve endings: Carry pain on C fibers, temp on Adelta fibers. Located in skin and seome viscera

Meissner corpuscles: Carry fine touch and position on large myelinated fibers that adapt quickly. Found on hairless skin

Pacinian corpuscles: Carry vibration and pressure on large myelinated fibiers that adapt quickly. Found in deep skin layers, ligaments, and joints.

Merkel discs: Carry pressure, deep touch, and position on large myelinated fibers that adapt slowly. Found in fingertips and superficial skin

Ruffini corpuscles: Carry pressure information on slow adapting dendritic endings within the capsule

22

Layers of a peripheral nerve

Endoneurium: surrounds single nerve fibers
Perineurium: surround fasicle of nerve fibers
Epineurium: dense connective tissue surrounding entire nerve

23

Location of neurotransmitter synthesis: NE, DA, 5-HT, ACh, GABA

NE: locus ceruleus of the pons
Dopamine: ventral tegmentum and substantia niagra of midbrain
5-HT: Raphe nuclei in brainstem
ACh: Basal nucleus of Meynert
GABA: nucleus accumbens

24

Components of BBB

1. Tight junctions between nonfenestrated capillary endothelial cells
2. Basement membrane
3. Astrocyte foot processes

25

OVLT

Area of hypothalamus not protected by BBB that senses changes in osmolarity.

26

Area postrema

Area of hypothalamus not protected by BBB that responds to emetics

27

Supraoptic nucleus

Part of hypothalamus that makes ADH

28

PAraventricular nucleus

Part of hypothalamus that makes oxytocin

29

Hypothalamus: lateral, ventromedial, anterior, posterior, suprachiasmic nucleus

Lateral area: hunger, inhibited by leptin
Ventromedial area: Satiety, stimulated by leptin
Anterior hypothalamus: Cooling, parasympathetic
Posterior hypothalamus: Heating, sympathetic
Suprachiasmic nucleus: Circadian rhythm

30

Circadan rhythm

Controlled by suprachiasmic nucleus. Drives nocturnal release of ACTH, prolactin, melatonin, norepinephrin.