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Flashcards in Spinal Cord physiology Deck (24)
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Two functions of the spinal cord:

1. Propagates nerve impulses (in white matter)
2. Integrates information (in grey matter)

1

Two major sensory tracts:

1. Spinothalamic tract
2. Posterior column

2

Spinothalamic tract

One of the two main sensory tracts.

Conveys nerve impulses for sending pain, temperature, itching, tickling, deep pressure and crude touch.

3

Posterior column

One of the two main sensory tracts. (Most of sensory tract)

Discriminative touch. Light pressure, vibrations, conscious proprioception.

4

Conscious proprioception

Awareness of positions and movements of your muscles, tendons and joints.

5

Posterior column is made up of what two tracts:

Gracile fasciculus
Cuneate fasciculus

6

Two main motor tracts

1. Direct pathway (intrapyramidal)
2. Indirect pathways (extrapyramidal)

7

Direct motor pathway

Nerve impulses originates in cerebral cortex.

Voluntary movements of skeletal muscle.

8

Indirect motor pathways

Extrapyramidal

Nerve impulses originate in brain stem.
Causes automatic movements.
Helps coordinate movement with visual stimuli.
Maintains skeletal muscle tone
Sustains contraction of postural muscles
Maintain equilibrium by regulating muscle response to head movement.

9

Reflex

Fast, involuntary and unplanned sequence of actions that occurs in response to a particular stimulus.

10

Spinal reflex

Integration in grey matter of spinal cord

11

Cranial reflex

Integration in brain stem

12

Somatic reflex

Involves contraction of skeletal muscle.

13

Autonomic reflex

AKA visceral reflex

Not usually consciously perceived.
Smooth or cardiac muscle, glands.

14

Five (ish) components of a reflex arc

1. Sensory receptor
2. Sensory neuron
3. Integrating centre
4. Motor neuron
5. Effector.

15

What is the only monosynaptic reflex arc?

Stretch reflex.

16

What is the only contralateral reflex?

Crossed extensor reflex

17

Intersegmental Reflex Arc

A single sensory neuron activates a number of motor neurons, at different segments of the spinal cord.

18

Reciprocal inhibition/innervation

Sensory neuron from GTO synapses with excitatory interneuron, which synapses with motor neuron in antagonistic muscle.

19

Stretch reflex

Contraction of skeletal muscle in response to stretch. Prevents over stretching.

Monosynaptic
Ipsilateral.

1. Muscle spindles
2. Posterior nerve root
3. In spinal cord, synapses with motor neuron in anterior gray horn
4. Motor neuron
5. Muscle contracts.

20

Muscle tone

Degree of contraction when muscle is at rest.
Set my muscle spindle.

21

Tendon reflex

Relaxation of muscle when under too much tension.

Ipsilateral
Polysynaptic

1. GTO stimulated by tension in tenson
2. Nerve impulses to SC
3. Activates inhibitory interneuron what synapses with motor neuron
4. Motor neuron inhibited
5. Muscle relaxes.

22

Flexor/Withdrawl reflex

Pain Withdrawl response.

Polysynaptic
Ipsilateral
Intersegmental

1. Sensory receptor or pain sensitive neuron
2. Nerve impulses to SC
3. Activates interneuron that extend to several SC segments
4. Several motor neurons activated
5. Relevant muscles contract

23

Crossed Extensor Reflex

Occurs with flexor/Withdrawl reflex. Compensatory balance

Contralateral
Polysynaptic
Intersegmental

1. Pain sensitive neuron
2. Sensory neuron impulse to SC
3. Activation of several interneuron a
4. Excited motor neurons to muscles on unaffected side
5. Contraction of opposite side muscles.