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Anatomy > Chapter 13 > Flashcards

Chapter 13 Flashcards

1
Q

can the spinal cord process info

A

yes

has some gray matter - a little

  • for somatic reflexes (instant responses- something too hot, primate)
  • common activities (walking/locomotion)
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2
Q

what does the spinal cord consist of

A

mostly white matter for transferring info (electrical signals) out of PNS to CNS and vice versa

some gray mater for minimal processing

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3
Q

the spinal cord it the _________ _________ that connects the brain with the _________ ________

A

the spinal cord is the information highway that connects the brain with the lower body

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4
Q

what are the functions of the spinal cord

A

Conduction
- nerve fibers conduct sensory/motor info in spinal cord

neural integration
- the neurons receive input multiple sources, integrate it, execute appropriate output

locomotion
- central pattern generators

Refelexes
-involuntary responses to stimuli that are vital to posture, coordination, protection (something hot/cut self = somativ reflexes )

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5
Q

central pattern generators

A

within spinal cord, give locomotion

groups of neurons that coordinate repetitive sequences of contractions for walking

they are little sections of gray matter in the spinal cord that put together muscle contraction processes from brain to tell when to contract when walking

begin to develop at 7months of age

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6
Q

describe the spinal cord/location

A

cylinder of nervous tissue arises from brainstem at the foramen magnum of skull

occupies upper 2/3 of vertebral canal

inferior margins end at L1 (varies)

gives rise to 31 pairs of spinal nerves (aka branches 31 times)

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7
Q

why does the spinal cord branch 31 times if there are only 25 vertebrae

A
  1. branch spinal nerve between occipital bone and C1 and is called spinal never 1
  2. past medullary cone, spinal cord begins to taper- spinal nerve branches begin to stick out of sacrum
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8
Q

what is the anterior median fissure and posterior median sulcus

A

longitudinal grooves on anterior and posterior sidees

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9
Q

what is the spinal cord divided into

A

cervical
thoracic
lumbar
sacral regions

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10
Q

what are the two areas of the spinal cord that are thicker than elsewhere (diameter wise)
buldge of white mater

A

cervical enlargement: nerves to and from upper appendages

lumbar enlargement: nerves to and from lower appendages

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11
Q

what is the medullary cone (conus medullaris)

A

where the cord tapers to a point inferior to lumbar enlargement

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12
Q

what is the cauda equina

A

bundle of nerve roots that occupy the vertebral canal from L2 to S5

spinal cord branches sticks out of inferior portion of apex

inervates lower appendages

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13
Q

what are meniges

A

three fibrous membranes that enclose the brain and spinal cord

separate soft tissue of central nervous system from bones of cranium and vertebral canal

contains dura mater, arachnoid mater, pia mater

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14
Q

what is the dural sheath

A

it is a part of the dura mater that surrounds the spinal cord and instead of binding to periosteum of cranium bones, it is separated from vertebrae by epidural space

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15
Q

what is epidural space for

A

has some blood vessels

its an air space

some protection

maybe flexibility

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16
Q

what is the arachnoid membrane

A

adheres to dura mater and is separated from pia by fibers spanning the subarachnoid space that is filled with cerebrospinal fluid

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17
Q

what is special about the subarachnoid space in spinal cord

A

varies in thickness due to varying volumes of CSF

small in cervical

large in lumbar

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18
Q

what is special about the subdural space in spinal cord

A

lots of blood vessels to allow stuff to go to CSF of subarachnoid space, filtered by arachnoid membrane

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19
Q

what is different about pia matter in spinal cord

A

connects to anterior/posterior fissures of spinal cord (adheres to spinal cords surface)

it also has parallel collagen fibers called ligaments

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20
Q

describe the ligaments in pia mater

A

ligaments- parallel collagen fibers

form three different ones

  1. denticulate ligament
    - the collagen extends from spinal cord, through all meniges to attach to the vertebral arches
    - prevents LATERAL movement of spinal cord
  2. coccygeal ligament
    - extension of the pia collagen fibers that attach to sacrum and coccyx
    - prevent SUP/INF movement of spinal cord
  3. occupital ligament
    - extension of pia collagen fibers that attach to occcipital bone
    - prevent SUP/INF movement of spinal cord
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21
Q

explain an epidural injection

A

given in the epidural space (usually lumbar region)

anesthetic

stops nerve impulses in that compartment and anything below

decreasing pain

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22
Q

what is spina bifida

A

congenital defect where one or more vertebrae fail to form a complete vertebral arch for enclosure of the spinal cord

spinal cord grows outside of vertebrae and even outside of skin

common in lumbosacral region

spinabifida cystica = most serious form

1- 1000 babies get

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23
Q

what causes spina bifida

A

b vitamin deficiency (folic acid )

now put in flour to prevent because important in reproductive women

defect occurs within first 4 weeks of development - must take folic acid 3 months before conception to help prevent

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24
Q

describe the cross section of the spinal cord

A

central area of gray mater (deep) - butterfly

surrounded by white mater in three columns

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25
Q

describe the gray matter of spinal cord generally

A

neuron cell bodies with little myelin (lots of nisel bodies, meant for info processing and synaptic integration)

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26
Q

white matter of the spinal cord generally

A

abundantly myelinated axons

thicker than gray

carry signals from one part of CNS to another (afferent and efferent)

27
Q

describe the buttefly of gray matter

A

has posterior (dorsal) horns

has anterior (ventral) horns (thicker)

posterior (dorsal) root and anterior (ventral) root

gray commisure:

lateral horns

28
Q

what are the posterior (dorsal) root and anterior (ventral) root

A

posterior root: spinal nerves carries only sensory fibers

anterior root: spinal nerves carry only motor fibers

29
Q

what is the gray commissure

A

connects left and right side of buttefly of gray matter

has central canal lined with ependymal cells and filled with CSF

transfers info back and forth

30
Q

what are the lateral horns

A

on the gray mater of spinal cord

visible from T2 to L1 only

contains neruons of sympathetic nervous system

31
Q

describe the white matter of the spinal cord and the columns

A

white matter surrounds gray mater

consist of bundles of axons that course up and down the cord providing communication between different levels of the CNS

contains columns (funiculi) - 3 pairs of thee white matter bundles
-posterior, lateral (2), and anterior on each side
32
Q

what are the tracts of fasciuli

A

each column of white matter is divided into four different tracts

they are more specific bundles of axons (either all afferent or all efferent)

33
Q

fibers in a given tract have similar….

A

origin, destination, and function

34
Q

what are the different tracts

A

ascending tract: carry sensory info up

descending tract: carry motor info down

35
Q

what is decussation

A

crossing the midline that occurs in many tracts so that brain senses and controls contralateral side of body

occurs in 2 places
1. superior to T6 = descussate at brainstem

  1. anything below T6= decussate at T6
36
Q

what is the difference between contralateral and ipsilateral

A

contralateral:

  • when the origin and destination of a tract are on opposite sides of the body
  • decussates

ipsilateral
- when the origin and destination of a tract are on the same side of the body
does not decussate

37
Q

where do ascending tracts carry sensory signls

A

up the spinal cord

38
Q

sensory signals must do what when traveling in an ascending tract

A

sensory signals must travel across three neurons from origin (receptors) to destination in the sensory areas of the brain

first order neurons
second order neurons
third order neurons

decussation occurs at the level of either T6 or brainstem

39
Q

what is the difference between the different neurons that a sensory signal must travel across to reach destination in an ascending tract

A

First-order neurons: -detect stimulus and transmit signal to spinal cord or brainstem
-gather sensory info

Second-order neurons:

  • continues to the thalamus at the upper end of the brainstem
  • carries info from 1st order to brainstem
  • synapses with 3rd order neuron

Third-order neurons:
-carries the signal the rest of the way to the sensory region of the cerebral cortex

most sensory info are 3rd order pathway

40
Q

what is a descending tract

A

carries motor signals down brainstem and spinal cord

involve two motor neurons

ALL decussation occurs in brainstem

41
Q

what are the two motor neurons involved in descending tracts

A

Upper motor neuron:
-originates in cerebral cortex or brainstem and terminates on a lower motor neuron

Lower motor neuron:

  • neurosoma is in brainstem or spinal cord
  • Axon of lower motor neuron leads to muscle or other target organ
42
Q

what is poliomyelitis

A

Disease causes destruction of motor neurons leading to skeletal muscles, causing muscle atrophy from lack of innervation

caused by poliovirus

destroys motor neurons in brainstem/anterior horn of spinal cord

signs: muscle pain, weakness, loss of some reflexes, paralysis, muscular atrophy, respiratory arrest

virus spreads by fecal contamination of water

43
Q

Lou Gehrig Disease/ALS

A

destruction of motor neurons and muscular atrophy

Also sclerosis (scarring) of lateral regions of the spinal cord

Astrocytes fail to reabsorb the neurotransmitter glutamate from the tissue fluid
-Accumulates to toxic levels

Early signs: muscular weakness; difficulty speaking, swallowing, and using hands

-Sensory and intellectual functions remain unaffected

44
Q

how does spinal cord communicate with the rest of the body

A

by way of spinal nerves

45
Q

what is a nerve

A

a cord-like organ composed of numerous nerve fibers (axons) bound together by connective tissue

46
Q

nerve fibers of the peripheral nervous system

A

surrounded by Schwann cells forming neurilemma and myelin sheath around the axon

47
Q

what are the difference between sensory, motor, and mixed nerves

A

sensory (afferent) nerves
-Carry signals from sensory receptors to the CNS

Motor (efferent) nerves
-Carry signals from CNS to muscles and glands

Mixed nerves
-Consists of both afferent and efferent fibers

48
Q

what can both sensory and motor fibers be described as

A

somatic or visceral

General or special

49
Q

what is a ganglion

A

cluster of neurosomas outside the CNS

Enveloped in an endoneurium continuous with that of the nerve and held together by Satellite cells

also bundles f nerve fibers leading into and out of the ganglion

posterior root ganglion associated with spinal nerves

50
Q

how many pairs of spinal nerves are there (mixed nerves)

A

31 pairs

8 cervical (C1–C8)

  • First cervical nerve exits between skull and atlas
  • Others exit at intervertebral foramina

12 thoracic (T1–T12)

5 lumbar (L1–L5)

5 sacral (S1–S5)

1 coccygeal (Co1)

51
Q

each spinal nerve is formed from two roots (proximal branches).

what are the two roots

(Repeat question, more info added)

A

posterior (dorsal) root

  • sensory input to spinal cord
  • has a posterior root ganglion: contains neurosomas of sensory neurons carrying signals to the spinal cord

anterior (ventral) root
- is motor output out of spinal cord

52
Q

what forms the cauda equina

A

formed from roots arising from L2 to Co1

53
Q

what is the cervical plexus

A

in the neck

C1-C5

supplies neck and phrenic nerve to the diaphram

54
Q

what is the brachial plexus

A

near the shoulder

C5-T1

supplies upper limbs and some of shoulder and neck

median nerve: associated with carpal tunnel syndrome

55
Q

what is the lumbar plexus

A

in the lower back

L1-L4

supplies abdominal wall, anterior thigh, and genetalia

56
Q

what is the sacral plexus

A

in the plevis

L4, L5, and S1 to S4

supplies remainder of lower trunk and lower limb

57
Q

coccygeal plexus

A

S4, S5, Co1

58
Q

describe chicken pox

A

common disease of early childhoodf

caused by varicella-zoster virus

produces itchy rash that clears up without any complications

59
Q

where is the chicken pox virus stored in the body

A

after chicken pox, the virus remains in body for life in the posterior root ganglia

it is kept in check by the immune system

60
Q

shingles

A

also called the herpes zoster

localized disease caused by the virus traveling down the sensory nerves when immune system is compromised

common after age 50

painful trail of skin discoloration and fluid filled vesciles along path of nerve

usually in chest and waist on one side of the body

pain and itching

childhood chickenpox vaccinations reduce the risk of shingles later in life

no sex link

61
Q

what is a dermatome

A

a specific area of the skin that conveys sensory input to a spinal nerve

detects fine touch and pressure

62
Q

dermatome map

A

diagram of the cutaneous regions innervated by each spinal nerve

63
Q

dermatomes do what with their edges

A

they ovelap edges as much as 50%

necessary t anestheize three successive spinal nerves to produce total loss of sensation in one dermatome

Anatomy (20 decks)

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