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Flashcards in Introduction to the Nervous System Deck (41)
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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)

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

3
Q

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

A

motor (efferent)

sensory (afferent)

visceral motor: autonomic nervous system –> sympathetic & parasympathetic

4
Q

neuron (definition)

A

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

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

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

7
Q

multipolar cell

A

contains many processes (dendrites & axons)

8
Q

peripheral nervous system

A

consists of nerve fibers & cell bodies outside central nervous system

9
Q

peripheral nerve

A

bundle of nerve fibers (axons) in PNS

10
Q

ganglion

A

collection of nerve cell bodies in PNS

11
Q

cranial nerves

A

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

12 sets of cranial nerves

12
Q

spinal nerves

A

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

31 sets of spinal nerves

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

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

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

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

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
Q

at birth, spinal cord ___

A

terminates at L3

26
Q

in adults, spinal cord terminates at ___

A

intervertebral disc b/n L1 & L2

27
Q

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 ___

A

L1, L2

lumbar, sacral, coccygeal, a considerable distance within the vertebral canal to reach their respective intervertebral foramina

cauda equina

28
Q

two fusiform enlargements of spinal cord

below the lower enlargement, the spinal cord tapers off into the ___

A

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
Q

meninges

A

protective barrier (membrane) b/n bone & soft tissue of CNS

30
Q

dura mater:

definition

spinal dura is separated from vertebrae by ___ which contains ___

the dura forms the ___ which continues down to the ___ vertebrae

A

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
Q

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 ___

A

delicate membrane of meninges

inner surface, cerebrospinal fluid

arachnoid, pia mater, cerebrospinal fluid

arachnoid trabeculae, subarachnoid space

32
Q

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

A

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
Q

subarachnoid space:

lies below ___

encloses ___

enlargement caudal to conus medullaris containing cauda equina is ___ which extends from ___ to ___

A

arachnoid mater

spinal cord & spinal nerve roots

lumbar cistern, L2, S2

34
Q

lumbar puncture (spinal tap)

A

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
Q

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 ___

A

lower back pain & lower limb pain

compression anteriorly, stretching/tension posteriorly, posteriorly

herniate, compress

posterolaterally, thin, ligaments

symptomatic, spinal nerve roots

36
Q

spinal cord segment

A

region of spinal cord to which a spinal nerve is attached

37
Q

dermatome

A

area of skin supplied by dorsal (sensory) root of spinal nerve

38
Q

myotome

A

muscle mass innervated by ventral (motor) root of spinal nerve

39
Q

nerve plexus

A

network of nerve fibers

40
Q

somatic nerve plexus

A

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
Q

autonomic nerve plexus

A

network of sympathetic & parasympathetic nerve fibers

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