Introduction to the Nervous System Flashcards

1
Q

nervous system is structurally divided into ___ & ___

A

central nervous system (CNS) - brain (encased in skull) & spinal cord (encased within vertebral column)

peripheral nervous system (PNS) - cranial nerves (12) & spinal nerves (31)

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2
Q

nervous system is functionally divided into ___ & ___ & is found throughout the ___ & ___ nervous systems

A

somatic nervous system (body wall) - innervates structures derived from embryonic somites or branchial arches (ex. skin & body wall, skeletal muscles, skeletal system, joints, etc.)

visceral nervous system (internal organs) - innervates visceral structures of body (ex. heart & blood vessels, digestive systems, respiratory system, urinary system, reproductive system, glands, smooth muscle, etc.)

central & peripheral

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3
Q

somatic & visceral nervous systems are both divided into ___ & ___, & further into ___

A

motor (efferent)

sensory (afferent)

visceral motor: autonomic nervous system –> sympathetic & parasympathetic

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4
Q

neuron (definition)

A

structural & functional unit of nervous system that’s specialized for rapid communication

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5
Q

neuron (components)

A

cell body

dendrites - carry impulses toward cell body (often, not always)

axon (fiber) - carries impulses away from cell body, neurons always have one and only one axon

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6
Q

neuron (communication)

A

neurons communicate w/ each other at synapses

communication occurs by means of chemical agents called neurotransmitters secreted by one of the neurons

neurotransmitter may either excite or inhibit another neuron

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7
Q

multipolar cell

A

contains many processes (dendrites & axons)

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8
Q

peripheral nervous system

A

consists of nerve fibers & cell bodies outside central nervous system

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9
Q

peripheral nerve

A

bundle of nerve fibers (axons) in PNS

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10
Q

ganglion

A

collection of nerve cell bodies in PNS

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11
Q

cranial nerves

A

originate from brain & exit cranial cavity through foramina (openings in skull bones)

12 sets of cranial nerves

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12
Q

spinal nerves

A

arise from spinal cord & exit through intervertebral foramina in vertebral column

31 sets of spinal nerves

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13
Q

typical spinal nerve

two roots: ___ & ___

A

arises from spinal cord by rootlets which converge to form two nerve roots

dorsal (sensory) root

ventral (motor) root

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14
Q

dorsal root:

carries ___ (___) impulses ___

sensory neuron cell bodies located in ___ located in ___

sensory neurons have a ___ process that ___, & these cells are termed ___

A

sensory, afferent, toward CNS

a swelling on the dorsal root called the dorsal root ganglion, intervertebral foramen

single, emanates from the cell body which splits in a t-like fashion into a peripheral & a central process, pseudounipolar neurons

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15
Q

central root:

carries ___ (___) impulses ___

motor neuron cell bodies located in ___

motor neurons have ___ processes & these cells are termed ___

A

motor, efferent, away from CNS toward some peripheral structure (muscle, gland, etc.)

central horn of spinal cord

many (numerous dendrites & one axon), multipolar neurons

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16
Q

immediately after the dorsal & ventral roots join forming the ___, it splits into a ___ & ___

both of these have ___ components

A

mixed (sensory & motor) spinal nerve

dorsal ramus - supplies skin & muscles of back

ventral ramus - supplies skin & muscles of anterior side of body & limbs

sensory & motor

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17
Q

somatic sensory fibers:

general somatic ___

reach ___ level

they may be ___ or ___ sensations

A

afferent (GSA)

conscious

exteroceptive (touch, pressure, vibration, pain, & temperature) from skin

pain & proprioceptive from muscles, tendons, & joints - convey info on joint position & tension of tendons & muscles, providing info on how body & limbs are oriented in space

18
Q

somatic motor fibers:

general somatic ___

sole target tissue of somatic motor fibers is ___ & their only effect is to ___ them & cause them to ___

A

efferent (GSE)

skeletal muscle fibers, stimulate, contract

19
Q

visceral sensory fibers:

general visceral ___

fibers transmit ___

reach ___ level

A

afferent (GVA)

pain or subconscious visceral reflex sensations (e.g. info concerning organ distension, blood gas & blood pressure levels, etc.)

not conscious (internal bodily functions)

20
Q

visceral motor fibers:

general visceral ___

aka ___

fibers innervate ___

fibers may have a ___effect on target tissue

A

efferent (GVE)

autonomic nervous system (ANS)

a wide variety of visceral structures (e.g. smooth muscle, glands, blood vessels, the heart, etc.)

stimulatory or inhibitory

21
Q

spinal cord

A

cylindrical structure extending from foramen magnum to intervertebral disc b/n L1 & L2 (not all the way to tip of coccyx)

22
Q

ordered segmented pattern throughout spinal cord’s length gives rise to 31 pairs of spinal nerves

A

8 cervical - 7 vertebrae, 1st nerve b/n skull & C1 (b/n occipital bone & atlas), 2nd-7th exit above vertebra, 8th nerve exits under vertebra

all following nerves exit under vertebra

12 thoracic

5 lumbar

5 sacral

1 coccygeal

23
Q

spinal cord & vertebral column grow at ___ rate until ___, after which the ___ grows much more ___ than the ___

A

same

end of 3rd month of fetal development

vertebral canal

rapidly

spinal cord

24
Q

at six months of fetal development, spinal cord ___

A

terminates at S1

25
at birth, spinal cord ___
terminates at L3
26
in adults, spinal cord terminates at ___
intervertebral disc b/n L1 & L2
27
in adults, the coccygeal spinal cord segment is located at the level of the intervertebral disc b/n ___ & ___ vertebrae dorsal & ventral roots of lower ___, ___, & ___ spinal nerves must descend ___ collection of spinal nerve roots forms ___
L1, L2 lumbar, sacral, coccygeal, a considerable distance within the vertebral canal to reach their respective intervertebral foramina cauda equina
28
two fusiform enlargements of spinal cord below the lower enlargement, the spinal cord tapers off into the ___
cervical enlargement (C4/C5 - T1) - reflects large number of neurons serving brachial plexus (upper limbs) lumbar enlargement (L1 - S3) - reflects large number of neurons serving lumbosacral plexus (lower limbs) conus medullaris (termination of cord) *refers to nerves, not vertebrae
29
meninges
protective barrier (membrane) b/n bone & soft tissue of CNS
30
dura mater: definition spinal dura is separated from vertebrae by ___ which contains ___ the dura forms the ___ which continues down to the ___ vertebrae
outermost tough, dense, fibrous layer of meninges epidural space, adipose tissue & a venous blood plexus (veins) dural sac (a long tubular sheath within the vertebral canal that houses both brain & spinal cord), S2
31
arachnoid mater: definition held against the___ of the dura by the pressure of ___ the subarachnoid space lies between the ___ & the ___ and contains ___ delicate strands of connective tissue called ___ span the ___
delicate membrane of meninges inner surface, cerebrospinal fluid arachnoid, pia mater, cerebrospinal fluid arachnoid trabeculae, subarachnoid space
32
pia mater: definition closely adherent to ___ spinal cord suspended in dural sac by ___ at apex of cord, a continuation of pia mater continues as ___ which continues to end of dural sac at ___, pierces the dural sac & receives an investment of arachnoid & dura mater & is now referred to as the ___ which attaches to the tip of the coccyx
delicate, highly vascular, innermost layers of meninges neural tissue saw-toothed denticulate ligaments - lateral extensions of pia mater midway b/n dorsal & ventral nerve roots, attach to inner surface of dura mater, anchor spinal cord within sac filum terminal interum (after conus medullaris), S2, filum terminale externum or coccygeal ligament
33
subarachnoid space: lies below ___ encloses ___ enlargement caudal to conus medullaris containing cauda equina is ___ which extends from ___ to ___
arachnoid mater spinal cord & spinal nerve roots lumbar cistern, L2, S2
34
lumbar puncture (spinal tap)
performed to withdraw a sample of cerebrospinal fluid for examination spinal cord terminates at level of L1/L2, while lumbar cistern of subarachnoid space extends down to lower border of S2 a needle introduced into lumbar cistern below L4 pushes nerve roots of cauda equina aside w/o causing damage
35
herniation of nucleus pulposes: herniation/protrusion of gelatinous nucleus pulposus into/through anulus fibrosus is a well-recognized cause of ___ flexion of the vertebral column produces ___ & ___, squeezing the nucleus pulposus further ___ toward the thinnest part of the annulus fibrosus if the annulus fibrosus has degenerated, the nucleus pulposus may ___ into the vertebral canal & ___ the spinal cord or the nerve roots of the cauda equina herniations of the nucleus pulposus usually extend ___, where the anulus fibrosus is relatively ___ & doesn't receive support from either the anterior or posterior longitudinal ___ a posterolateral herniated IV disc is more likely to be ___ b/c of the proximity of ___
lower back pain & lower limb pain compression anteriorly, stretching/tension posteriorly, posteriorly herniate, compress posterolaterally, thin, ligaments symptomatic, spinal nerve roots
36
spinal cord segment
region of spinal cord to which a spinal nerve is attached
37
dermatome
area of skin supplied by dorsal (sensory) root of spinal nerve
38
myotome
muscle mass innervated by ventral (motor) root of spinal nerve
39
nerve plexus
network of nerve fibers
40
somatic nerve plexus
nerve plexus formed by ventral rami of certain spinal nerves ex. cervical plexus, brachial plexus, lumbar plexus, sacral plexus does have autonomic components, but principally sensory
41
autonomic nerve plexus
network of sympathetic & parasympathetic nerve fibers