Spinal Cord and Reflexes Flashcards

1
Q

Describe the basic anatomy of the spinal cord.

A

The spinal cord is located within the vertebral canal of the vertebral column, surrounded and protected by three meninges

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2
Q

Describe the white and gray matter of the spinal cord.

A

In the spinal cord white matter surrounds a centrally located H-shaped mass of gray matter.

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3
Q

What is the central canal?

A

A small space in the gray matter, extending the length of the cord and contains cerebrospinal fluid.

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4
Q

The spinal cord appears to be segmented because?

A

31 pairs of spinal nerves emerge from it a regular intervals

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5
Q

How are spinal nerves connected to the spinal cord?

A

Each connected by two bundles of axons called roots

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6
Q

What are the two roots called?

A

Posterior (dorsal) root

Anterior (ventral) root

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7
Q

What is the posterior (dorsal root)?

A

Contains only sensory axons which conduct nerve impulses from the sensory receptors in PNS into CNS. Each posterior root has a posterior root ganglion which is a bulge containing cell bodies of sensory neurons

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8
Q

What is the anterior (ventral) root?

A

Contains axons of motor neurons which conduct nerve impulses from CNS to muscles and glands.

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9
Q

What is a reflex?

A

An input that in addition to being sent to the brain can trigger an automatic response very quickly.

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10
Q

What are the three parts of a reflex?

A

Input
Relay
Output

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11
Q

What is a reflex input?

A

Event that causes reflect/ activation of sensory receptors and AP’s along sensory nerve endings

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12
Q

What is a reflex relay?

A

Connections in the CNS that are required for reflex

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13
Q

What is a reflex output?

A

Resulting muscle activity - AP’s along motor neurons resulting in muscle contraction

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14
Q

Describe the example of the stretch reflex.

A

Stretching done via small hammer, stimulates muscle fibres, sends AP’s up sensory neuron into spinal cord, SYNAPSES with motor neuron which then return to muscle, muscle contracts, stretch removed

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15
Q

What is the function of a reflex?

A

To allow body/ muscle to make automatic adjustments in length and load without waiting on brain

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16
Q

How does the spinal cord communicate with the brain?

A

Via Spinal Pathways or Tracts

17
Q

What are the two divisions of Spinal Tracts?

A

Ascending Sensory Tracts

Descending Motor Tracts

18
Q

Where are these Spinal Pathways/Tracts Located?

A

In the white matter of the spinal cord

19
Q

What spinal pathway an AP’s taken when travelling down the spinal cord to a motor neuron depends on the…

A

‘type’ of muscle it is destined for (type refers to the degree of control required for the output)

20
Q

For precise movement what spinal pathway is important?

A

The Corticospinal pathway

21
Q

For control of posture/movement and whole limbs what spinal pathway is important?

A

The Extrapyramidal pathway

22
Q

What side of brain controls what side of body?

A

The right cerebral hemisphere controls the left hand side of the body and the left cerebral hemisphere controls the right hands side of the body.

23
Q

What is crossing over in the nervous system?

A

When nerve axons cross over from right hand side of body to arrive at left hand side of brain and vice versa

24
Q

Where to axons cross over?

A

At the medulla

25
Q

Name two major sensory pathways.

A

Dorsal Column

Spinothalamic Pathway

26
Q

What sensations use the Dorsal Column route to travel to the brain?

A

Touch, vibration, pressure, two point discrimination, proprioception

27
Q

What sensations use the Spinothalamic route to travel to the brain?

A

Pain and temperature (lateral pathway)

Light touch and pressure (anterior pathway)

28
Q

What cells make the myelin sheaths in the PNS?

A

Schwann cells

29
Q

What cells make myelin sheaths in the CNS?

A

Oligodendrocytes

30
Q

Describe the segments of the spinal cord to bottom to top?

A

Coccyx - sacrum - lumbar - thoracic - cervical

31
Q

How many spinal nerve pairs are there for each spinal segment?

A

1 Coccygeal, 5 sacral, 5 lumbar, 12 thoracic, 8 cervical