1a Peripheral Nervous System + Disorders Flashcards

1
Q

What is the PNS composed of?

A

The nerves and ganglia outside the brain and spinal cord

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2
Q

What are the two divisions of the PNS?

A

The sensory (afferent) and motor (efferent) division

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3
Q

What are the two divisions of the motor peripheral nervous system?

A

Somatic and Visceral (Autonomic)

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4
Q

What are the two divisions of the autonomic nervous system?

A

Sympathetic and parasympathetic

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5
Q

How many pairs of cranial nerves are there?

A

12

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6
Q

How many pairs of spinal nerves are there?

A

31

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7
Q

What do somatic sensory neurones do?

A

They receive sensory input from the periphery - eg Skin, Skeletal Muscle and tendons

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8
Q

What are the some external receptors which detect somatic sensory stimuli and what do they detect?

A

Exteroreceptors detect pain, temperature and pressure

Noiceoreceptors
Mechanoreceptors
Thermoreceptors

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9
Q

What are the internal sensory receptors?

A

Proprioreceptors and enteroreceptors

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10
Q

What do muscle spindle receptors do?

A

Detect changes in the length of muscle

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11
Q

What do golgi tendon receptors do?

A

detect changes in the tension of tendons

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12
Q

From what do visceral sensory neurones pick up stimuli from? And what stimuli

A

Pain, fullness and blood pressure from thoracic, pelvic and abdominal organs

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13
Q

What do somatic motor neurones do?

A

Innervate skeletal muscle for movement

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14
Q

From where do somatic afferent nerves convey information?

A

Skin, skeletal muscle and joints

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15
Q

What is a dermatome?

A

Area of skin that is supplied by a single spinal nerve

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16
Q

What is a myotome?

A

Group of muscles innervated by a single spinal nerve

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17
Q

From where do visceral afferent nerve carry information?

A

Thoracic, Abdominal and Pelvic Organs

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18
Q

What does the sympathetic system innervate?

A

The visceral organs and vasculature

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19
Q

What does the parasympathetic system innervate?

A

Only visceral organs

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20
Q

What is a ganglion?

A

A collection of cell bodies outside the CNS

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21
Q

What is a nucleus?

A

A collection of cell bodies inside the CNS

22
Q

What is a plexus?

A

A network of interconnecting nerves

23
Q

Where do afferent fibers have their cell bodies?

A

In spinal (dorsal root) ganglia

24
Q

Where do visceral efferent nerves synpase?

A

An autonomic ganglion

25
Q

What is the perineurium?

A

A layer of connective tissue which covers the individual fascicles

26
Q

What is the epineurium?

A

The external vascular layer which covers the entire NERVE

27
Q

What is the endoneurium?

A

Layer of connective tissue which covers individual axons

28
Q

What are the two classification systems for nerves?

A
  1. Based on conduction velocity, with A being the fastest
  2. Based on axonal diameter - using roman numerals (I-IV) and one has largest diameter
29
Q

What do photoreceptors do?

A

Detect light in retina

30
Q

what is the specialized synpase betwen a motor neurone and a muscle called?

A

Neuromuscular juction

31
Q

What is a motor unit?

A

A single motor neurone together with all the muscle fibres it innervates

32
Q

What happens when one motor unit is stimulated?

A

all the muscle fibers in that unit will contract

33
Q

What is reflex action?

A

Involuntarily coordinated pattern of muscle contraction and relaxation

34
Q

Outline the process of the tendon reflex action

A
  1. Stretching stimulates sensory receptor (muscle spindle)
  2. Sensory neurone activated
  3. Sensory neurone activates motor neurone within the spinal cord (integrating centre)
  4. Motor neurone is activated
  5. Effector (quadricep muscle of thigh) contracts, causing a knee jerk
35
Q

What is meant by a monosynaptic reflex?

A

Simple reflex involving only one synapse between the sensory and motor neurone

36
Q

What is the antagonist muscle of the quadriceps?

A

Hamstring muscles

37
Q

What happens if there is a lesion in the dorsal root?

A

Loss of sensation in the dermatome supplied by the corresponding spinal nerve

38
Q

What happens if there is a lesion in a somatic sensory nerve?

A

loss of sensation in the area of disribution of that peripheral nerve

39
Q

Why is loss of sensation at dermatomes sometimes not detected?

A

There may some overlap in dermatome innervation

40
Q

What happens if there is a lesion in the ventral root?

A

Muscle weakness, as the spinal nerve that innervates the muscle has been shut off

41
Q

Why is paralysis of muscles not always seen?

A

More limb muscles are innervated by more than one nerve so paralysis is unlikely

42
Q

What happens if there is damage directly to the motor neurone?

A

Paralysis of the muscle as the impulse cannot reach the muscle

43
Q

Why are there 30 dermatomes but 31 spinal nerves?

A

C1 does not have a sensory root so dermatomes begin with C2

44
Q

What is lumbar spinal radiculopathy commonly known as?

A

Sciatica, caused by compression of the sciatic nerve

45
Q

what is a radiculopathy?

A

When the nerve root in the spine become compressed leading to pain, weakness and tingling sensations

46
Q

What can cause radiculopathy?

A

A slipped / herniated disc

47
Q

What is a slipped disc?

A

When the soft cushion of tissue between bones pushes out and presses on nerve

48
Q

What happens to the intervertebral foramine when there is a slipped disc?

A

It narrows

49
Q

What can be used to confirm diagnosis of sciatica?

A

The straight leg raise - stretches sciatic nerve and recreates the pain felt by the patient

50
Q

What are some treatment options for sciatica?

A

Painkillers, Exercise, Epidural infection delivered into the causal part of sine (sacral hiatus), decompression surgery

51
Q

What are some non disc causes of sciatica?

A

Other non-disc causes include malignancy (e.g. metastatic bone disease), arthritis, bone growths, piriformis syndrome (where the nerves are compressed by the contraction of the piriformis muscle in the buttocks).

52
Q

Which spinal segments are involved in the autonomic nervous system (visceral motor)

A

Thoracolumbar (T1-L2) and craniosacral outflow (cranial nerves III, VII, IX, X)