Neuro exam #1 Flashcards
Excitability
ability to generate an impulse
Conductivity
ability to transmit an impulse within itself
Influence
ability to influence another neuron
Afferent
towards the CNS (ascending)
Efferent
away from the CNS
Interneruron
transmitting from one neuron to another
Oligodendrocytes
make myelin sheath
Astrocytes
accumulate where neurons have been damaged feed blood brain barrier
Ependymal cells
secretion and regulation of CSF
Microglia
remove waste
Nerve regeneration
damaged nerves try to regrow CNS: limited ability PNS: can regenerate
Nerve impulse conduction
travels by the electrical transmission along the axon and the chemical transition between neurons (synapse) until impulse reaches its destination Resting: K high, Na low Depolarization: Na channels open and become high in cell Repolarization: K channels open, slowly enter, K rises and become high in cell again
Action potential
impulse reaches the end of the nerve fiber then transmitted across the junction between nerve cells at the synapse chemical interaction generates another action potential in the next neuron. Repeated until the impulse reaches its destination or end organ
Saltatory conduction
-Nerve conduction of the myelinated cells -action potential jumps from 1 node of Ranvier to the next
Nodes of Ranvier
gaps in myelin sheath
Synapse
Junction where nerve impulse is transmitted from one neuron to another neuron
Synaptic Transmission
presynaptic knob: release impulse synaptic cleft: space between neurons neurontransmitter: chemical involved in impulse from one neuron to another receptor site: next neuron picks up impulse (neurontransmitter: have excitatory or inhibitory effects)
CNS consists of…
brain and spinal cord
PNS….
12 pairs of cranial nerves 31 pairs of spinal nerves
Foramen Magnum
largest hole in the skull. where the spinal cord enters and exits
Meninges
3 protective membranes surround the brain and spinal cord (epidural space: btwn skull and dura) Dura: outer layer. thickest and toughest. (subdural space: below dura. btwn dura and arach) Arachnoid: Middle layer. thinner and more delicate (subarachnoid space: CSF flows here) Pia mater: innermost layer. Mush-like and very vascular.
Falx cerebri
dural fold separates the 2 cerebral hemispheres
Tentoriun cerebelli
-double dura layer folds btwn cerebral hemispheres and cerebellum. -allow for expansion of the one structure w/o altering another.
CSF
clear, colorless, odorless fluid -fills ventricles and subarachnoid space -shock absorber, cushions brain and spinal cord from injury -consists of nutrients (water, protein, O2 , CO2, Na, K, Cl, glucose)- NO RBCs.
Choroids plexus
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Brain requires how much of the body’s oxygen and glucose?
25%
Venous drainage
-exit via 2 vascular channels created by the dural layers called the dural sinuses -empty into jugular veins. NO VALVES. work by gravity.
Anterior circulation
from the carotid (branch into internal and external carotid)
Posterior circulation
subclavian and basilar artery. Basilar artery: vertebral arteries unite to become this in posterior circulation.
Circle of Willis
allows blood to circulates from one hemisphere to the other. -protects from changes in pressure or occlusion. -main components are the basilar artery and internal carotids.
Autoregulation
brain can self regulate blood supply -does this by changes of blood vessel diameter (independent of systemic BP)
Blood brain barrier
-barrier between blood capillaries and brain tissue -made up of tight capillaries and astrocytes -protects brain from potentially damaging agents like toxins -lipid soluble
Gyrus
folds on surface of the brain
Fissure
deep, predictable separation of the cerebral hemispheres
Cerebrum
largest part of the brain associated with sensory, motor, and higher mental functions
Cerebral cortex
outer layer of the brain (white and gray matter)
Frontal lobe
contra-lateral (control opp. sides) motor function, memory, cog. func, judgement, Broc’s area
Broca’s area
-Necessary for expressive speech. -formation of the spoken word. — damage causes difficulty forming words –cerebral dominancy is in the left frontal lobe
Parietal lobe
sensory, spacial awareness, body awareness
Temporal lobe
auditory (wernicke’s area)
Wernicke’s area
in charge of understanding written and spoken speech (damage is receptive aphasia)
Occiptial Lobe
area for vision and visual association
Basal ganglia
initiation, execution, and completion of voluntary and automatic movement.
Diencephalons
area in the brain just above the brainstem -contains the thalamus and hypothalamus
Thalamus
relay station for all sensation
Hypothalamus
regulates 1) autonomic NS (involuntary body functions) and 2) endocrine (pit. secretion, temp control, fluid balance, repro, metab, hunger sensor that controls appetite)
Limbic system
responsible for primal human function (feeding, sex, and emotions)
Brain stem
-medulla oblongata, pons, and midbrain -connects spinal cord with cerebrum with cerebellum -contains ascending and descending pathways -attachment for CN 3 thru 12 -responsible for reflexes : cough, hiccup, swallow, and vom)
Medulla oblongata
primary rhythm center (repsirations, vasomotor functions like heart rate/function, BP)
Reticular formation
neurons control the sleep-wake cycle
Cerebellum
responsible for coordination of motor function, balance, spine smooth movements
Spinal cord
-mass of nerve fibers -extends from C1 to L1
Cauda equina
horse tail look at the bottom of the spinal cord. (non-myelinated)
Spinal cord matter
“H” wider arms are ventral, motor. send messages out thinner posterior and sensory and messages come in
Ascending tracts
Carries sensory input dorsal column: (posterior) enters at spinal cord crosses at medulla and stops in thalamus and terminates in cerebral cortex. (position, movement, deep touch, kinesthesia) Spinocerebellar: enters spinal cord and straight to cerebellum. No crossing. (muscle tension, body position for coordination of movement) Spinothalmic: enters spinal cord and crosses to the opposite terminates in the thalmus. (pain and temp sensations)
Descending tracts
carry motor messages corticospinal: cortex frontal lobe crosses the medulla then descends into spinal cord (voluntary motor function) Upper motor neurons: located in cerebral cortex. lesions cause weakness, paralysis, hyperreflexia Lower motor neurons: connect to CNS. lesions cause weakness, paralysis, flaccidity, and hyporeflexia
Reflexes
involuntary response to a stimulus monosynaptic reflex: receptor organ, sensory neuron, info processed in the spinal cord, motor neuron.
CN #1
-Olfactory -smell -identify familial odors (each nostril individually with eyes closed)
CN #2
Optic (sensory only) -vision/peripheral vision -use snellen chart -p. vision- look at examiners nose and identify when you see finger with one eye covered
CN #3, #4, #6
3: oculomotor 4: trochlear 6: abducens #3 function: eye movement, eyelid elevation, and pupil constriction. #4: eye movement test by have the pt follow the examiners finger while making an “N” and pen light for pupil constriction
CN #5
Trigeminal (sens & motor) function: facial sensation and chewing test: cotton ball on forhead, cheeks, jaw with eyes closed. clench teeth and open jaw against resistance
CN #7
Facial (sens & motor) function: taste and facial expression test: taste sugar and salt on tongue. smile, puff out cheeks, close eyes and examiner try to open.
CN #8
Acoustic or vestibulocochlear (sens only) function: hearing and equilibrium test: tuning fork, watch ticking, rustle fingers, whisper test. ask to walk in a straight line
CN #9 & #10
9: glossopharyngeal #10: vagus function: 9: taste on posterior tongue, pharynx, larynx. gag and swallow. 10: sensation of pharynx and larynx, smooth muscle sensation. gag and swallow. test: gag reflex with tongue depressor or make “k” sound. and ask to swallow.
CN #11
Spinal accessory (motor) function: sternocladi, trap, and neck muscles test: shrug shoulders and turn head (against resistance)
CN #12
Hypoglossal (motor) function: tongue muscle test: stick out tongue and see if it’s midline and not deviated.
Autonomic nervous system
effects voluntary function of cardiac, smooth muscles, and glands -maintain a relatively stable environment for the body. -Sympathetic: fight or flight -Parasympathetic: rest and digest
Roots of spinal nerves
dorsal root: sensory ventral root: motor fibers detach from ventral root dermatomes: area of skin innervated by a specific sensory spinal nerve root myotome: muscle group innervated by a single motor fiber