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Physiology 190 > The Spinal Cord > Flashcards

The Spinal Cord Flashcards

1
Q

What is the spinal cord (SC)?

A

= bundles of nervous tissue and supporting cells
> extends from the medulla oblongata to the superior border of the lumbar 2 vertebra

  • integration center = provides quick, reflexive responses to stimuli
  • sc is the pathway for sensory input to the brain and motor output away from the brain
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2
Q

Define conus medullaris

A

= the lower end of the sc

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3
Q

Define filum terminale

A

=secures the sc to the coccyx (is a pia mater extension)

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4
Q

What does the sc look like?

A

it is oval shaped slightly, and flattened posteriorly- anteriorly

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5
Q

What protects the sc? (4)

A
  • vertebral colum
  • spinal meninges
  • CSF
  • fat/connective tissue
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6
Q

Vertebral column provides?

A

the back bone, skeletal support/protection

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7
Q

Spinal meninges provide? What are the three membranes?

A
  1. dura mater (superficial)
  2. arachnoid layer
  3. pia mater (deepest)
  • is connective tissue surrounding the core
  • are continuations of the cranial meninges encircling the brain
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8
Q

CSF provides? Where does it lay?

A

lies between the inner and middle meninges (arachnoid and pia)

  • reduces friction
  • absorbs shock
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9
Q

Fat/ connective tissue layer provides?

A

insulation, cushion.

lies in the epidural space (on top of dura) between the dura and vertebral canal

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10
Q

Define spinal nerves

A

= the paths of communication between sc and body

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11
Q

How many spinal nerves do we have?

A

31 pairs > one pair from each vertebra set

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12
Q

What are the 5 sections these nerves are divided into?

A 
cervical (8)
thoracic (12)
lumbar (5)
sacral (5)
coccygeal (1)
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13
Q

What does each nerve contain?

A

a sensory neuron that supplies part of the body

|&raquo_space; dermatomes

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14
Q

Define dermatome

A

area of skin on body that supplies enery input to a given spinal segment in the CNS

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15
Q

Where do spinal nerves connect?

A

to the sc via ROOTs and ROOTLETS

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16
Q

What is the posterior root ganglion?

A

= dorsal root ganglion

contains the cell bodies of sensory neurons

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17
Q

What is the anterior root ganglion? and rootlets?

A

= ventral root ganglion

contains axons of motor neurons > conduct nerve impulses from the CNS to the effectors

18
Q

each root also ha rootlets. what are rootlets?

A

even smaller bundles of axons

19
Q

What are the steps of processing sensory input? (8)

A
  1. sensory receptors detect and input e.g. pain
  2. sensory neurons convey info > impulses to 3 places
  3. info goes to WM of sc and extends to brain
  4. info > posterior gray horn/ synapses with interneuron
  5. synapse with somatic motor neuron > sc reflex
  6. synapse with motor neurones from anterior gray horn
  7. somatic motor neurons convey output along neurons > thru anterior gray horn/root > enters sc > extends to skeletal muscles
  8. autonomic motor neurons extend to cardiac muscle, smooth muscle and glands
20
Q

What are the two grooves diving the white matter of the sc?

A
  1. posterior median sulcus

2. anterior median fissure

21
Q

Describe the shape of the gray matter in the sc

A

like a butterfly/ ‘letter h’

22
Q

What is the cross bar?

A

the gray commissure

23
Q

What is the central canal?

A

is full of CSF (continuous of the 4th ventricle), extends the length of the sc (right down the middle)

24
Q

What are the characteristics of gray matter?

A
  • contains dendrites and cell bodies
  • contains nuclei
    » motor nuclei provides output via motor neuron
    » sensory nuclei receives inout via sensory neuron
  • is unmyleinated
    -splits into horns
    > posterior (sensory)
    > anterior (motor)
    > lateral
25
What are the characteristics of white matter?
``` is bundles of white, myleinated axons - splits into horns > anterior white > posterior white > lateral white >>> each contain specific bundles of axons which can span long stances of sc and are called 'tracts' ```
26
What are the two functions of the SC?
1. nerve impulse propagation: WM contains ascending and descending tracts >> are the highways for nerve impulse propagation 2. integration of information: sc is an integration centre for some reflexes
27
What are two sensory tracts of the sc?
1. posterior column | 2. spinothalamic tract
28
Posterior column receives information on...
- touch - light pressure - vibration - proprioception
29
Spinothalamic tract receives information on...
- pain - warmth - crude touch - coolness - itching - tickling - deep pressure
30
The ascending tracts are of ___ information
SENSORY - keep CNS informed of changes in internal environment - are integrated in sc and brain by interneurons
31
the descending tracts are of ___ information
MOTOR - convey nerve impulses in from the cerebral cortex and brain stem - cause voluntary and automatic movements - where output to muscles travels
32
Define reflex. Can they be learned? Or are they innate?
= fast, involuntary sequence of events can be learned and innate - when integration occurs in sc: spinal reflex e.g. knee jerk - when integration occurs in brain stem: cranial reflex e.g. eye tracking
33
reflex arc
pathway followed by a nerve impulse, that produces a reflex
34
What are 4 examples of somatic spinal reflexes?
1. stretch reflex 2. tendon reflex 3. flexor (withdrawal) reflex 4. crossed-extensor reflex
35
Stretch reflex - what does it cause/control - how can it occur
causes contraction of the muscle that has been stretched can occur by 'tapping tendons' controls muscle length by contraction
36
Stretch reflex - stimulus - receptor - integration - nerve impulse - effect
S: muscle stretch or lengthen R: muscle spindles >> generate impulse I: sensory neuron > motor neuron in anterior gray horn (excitatory synapse) N: leaves the sc via the anterior root E: muscle contraction of the SAME muscle stimulated (ACH released > AP > contraction; antagonist relaxed)
37
Tendon reflex - what does it control - how can it occur
controls muscle tension by causing muscle relaxation before the force becomes SO GREAT that the tendons could be torn
38
Tendon reflex - stimulus - receptor - integration - nerve impulse - effect
S: increase in tendon tension R: golgi tendon organs I: sensory neuron > activates an inhibitory motor neuron (motor neuron synapse) N: inhibitory neuron inhibits (hyper.) the neuron THEREBY decreasing impulses generated E: muscle relaxation > relieves tension ( antagonist muscle contracts)
39
Flexor (withdrawal) reflex - what causes it - what does it cause
occurs with stepping on a tack (for example) stimulates pain neurons… is involved in the intersegmental reflex arc
40
Flexor (withdrawal) reflex - stimulus - receptor - integration - nerve impulse - effect
S: pain R: pain sensitive neuron receptors I: sensory neurons > activate interneurons > that extend to several sc segments N: interneurons > activate motor neurons > generate nerve impulse E: contraction of flexors in the IPSILATERAL thigh
41
Crossed- extensor reflex - what causes it - what does it cause
e.g. stepping on a tack >> causing you to lose BALANCE | synchronized flexion of stimulated leg and extension of contralateral leg
42
Crossed-extensor reflex - stimulus - receptor - integration - nerve impulse - effect
S: pain R: pain sensitive neuron receptors I: sensory neuron > activates several interneurons (synapse with motor neuron… - on the OPPOSITE side - and in several segments of the sc) N: interneurons activate motor neurons > generate nerve impulse E: contraction of extensors in thigh of UNstimulated leg switching the weight to the opposite leg

Physiology 190 (6 decks)

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