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BIOL 1191 > Ch. 13 - Spinal Cord > Flashcards

Ch. 13 - Spinal Cord Flashcards

1
Q

What are some functions of the spinal cord?

A
  1. process reflexes
  2. integrate EPSPs and IPSPs
  3. conduct sensory impulses to brain and motor impulses to effectors
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2
Q

What are the meninges and spaces from superficial to deep?

A 
epidural space
dura mater
subdural space
arachnoid mater
subarachnoid space
pia mater
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3
Q

What is the removal of CSF called and why is this done?

A

spinal tap/lumbar puncture; used to diagnose pathologies, administer drugs

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4
Q

Why are spinal taps usually performed between L3-L4 or L4-L5 in adults?

A

to avoid damaging the spinal cord that ends at L1-L2

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5
Q

Where is the cervical enlargement in the spinal cord? Where is the lumbar enlargement?

A

C4-T1; T9-T12

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6
Q

Describe to ratio of white matter to grey matter along the spinal cord

A

going down the spinal cord, the ratio of white to grey DECREASES due to more sensory neurons (axon tracts) at higher levels

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7
Q

What are the functions of white matter?

A

nerve transmission to and from brain

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8
Q

What are the functions of grey matter?

A

integration of nerve impulses (EPSPs, IPSPs)

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9
Q

What are the posterior grey horns of the SC?

A

where sensory info enters

  • axons of sensory neurons
  • axons + cell bodies of interneurons
  • somatic and autonomic
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10
Q

What are the anterior grey horns of the SC?

A

where output exits

  • somatic motor nuclei to sk muscles
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11
Q

What are the lateral grey horns of the SC?

A

autonomic motor nuclei to autonomic effectors (cardiac/smooth muscle, glands)

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12
Q

How is white matter organized in the SC?

A
  • divided into anterior, posterior, and lateral columns

- contain tracts (axon bundles in CNS)

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13
Q

What are 2 non-reflex functions of the SC?

A

grey - receives and integrates incoming/outgoing info

white - nerve impulse conduction to and from brain

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14
Q

How are the 31 pairs of spinal nerves named and numbered?

A

according to region and level of vertebral column from which they emerge (8C, 12T, 5L, 5S, 1C)

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15
Q

As spinal nerves are part of the PNS, how do they connect to the CNS?

A

via 2 bundles of axons (roots):

  • posterior root (contains sensory axons; afferent)
  • anterior root (contains motor axons; efferent)
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16
Q

Where are the cell bodies of sensory nerves?

A

posterior root ganglion

17
Q

Why is there a posterior root ganglion but not an anterior root ganglion?

A

because motor cell bodies are within the spinal cord (in the anterior grey horns)

18
Q

What is a possible of the formation of nerve plexuses instead of anterior rami directly going to part they supply?

A

safety feature; plexuses allow conduction of info even if one spinal nerve is cut; other nerves can carry info in/out

19
Q

Why is there thoracic plexus?

A

anterior rami of spinal nerves T2-T12 directly innervate the intercostal spaces (intercostal nerves)

20
Q

What are dermatomes?

A

specific segments of the skin that are innervated by all spinal nerves (except C1)
- spinal nerves carry sensory nerve impulses to spinal cord and brain

21
Q

What is transection?

A

injury that severs spinal cord; loss of sensation and motor control below level of injury

  • the higher the level of injury, the more severe the effect is
22
Q

What is a reflex?

A

a fast, predictable, involuntary response to changes in the environment that helps maintain homeostasis

23
Q

Where are spinal reflexes integrated?

A

grey matter of spinal cord

24
Q

What are the 5 components of a reflex arc?

A

sensory receptor, sensory neuron, integrating center, motor neuron, effector

25
Q

What are 4 important somatic spinal reflexes?

A
  • stretch reflex
  • tendon reflex
  • flexor reflx
  • crossed extensor reflex
26
Q

What is the purpose of a stretch reflex?

A

controls muscle length; prevents injury from overstretching by causing muscle to contract (shorten) when it is stretched

27
Q

Describe features of the stretch reflex

A
  • monosynaptic, ipsilateral
  • muscle spindle signals stretch of muscle
  • motor neuron activated and muscle contracts
28
Q

What is reciprocal innervation?

A

simultaneous contraction of one muscle and the relaxation of its antagonist (requires an interneuron; polysynaptic!)

29
Q

What is the purpose of a tendon reflex?

A

controls muscle tension; causes muscle relaxation when muscle force is too extreme

30
Q

Describe features of the tendon reflex

A
  • polysynaptic, ipsilateral
  • sensory receptors in tendons are activated
  • inhibitory interneuron stimulated
  • motor neuron is hyperpolarized, muscle relaxes
  • reciprocal innervation causes contraction of antagonist muscle group
31
Q

What is the purpose of the flexor (withdrawal) reflex?

A

moves a limb in response to a painful stimulus

32
Q

Describe features of the flexor reflex

A
  • polysynaptic, ipsilateral

- results in contraction of flexor muscles to move a limb to avoid injury or pain

33
Q

What is the purpose of the crossed extensor reflex?

A

helps maintain balance during flexor reflex

34
Q

Describe features of the crossed extensor reflex

A
  • polysynaptic, contralateral

- causes synchronized extension of joints of one limb and flexion of joints in opposite limb

35
Q

Describe the process of the flexor reflex

A
  • pain sensors send signal to SC
  • activation of interneurons that branch to diff SC segments
  • motor fibers in several segments are activated
  • multiple musc groups activated to move limb away
  • reciprocal innervation
36
Q

Describe the process of the crossed extensor reflex

A
  • pain sensors in R foot send signal to SC
  • activation of interneurons that synapse to motor neurons on contralateral side –> activate contralateral ext muscles
  • extensor muscles contract to extend L leg and maintain balance
  • reciprocal innervation

BIOL 1191 (16 decks)

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