Anatomy of the Peripheral Nervous System Flashcards

1
Q

What is the difference between a nucleus and a ganglion?

A

A collection of nerve cell bodies in the CNS is known as a nucleus; while a collection of nerve cell bodies in the PNS is known as a ganglion

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2
Q

What are neurones?

A

Nerve cells which receive and conduct impulses

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3
Q

What are the 3 main parts of a neurone?

A

Body, dendrites, axon

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4
Q

Which is longer, a dendrite or an axon?

A

Axon

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5
Q

Dendrites travel in which direction with regards to the neurone cell body?

A

Towards

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6
Q

Dendrites are effectively extensions of the neurone cell body, what is their function?

A

To increase surface area to allow the neurone to connect with other neurones

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7
Q

Axons travel in which direction with regards to the neurone cell body?

A

Away

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8
Q

What is the role of the axon?

A

To communicate with other neurones or effectors (muscles/glands)

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9
Q

What would be the main difference in the myelin sheath surrounding an axon in the PNS vs the CNS?

A

In the CNS, the myelin sheath will be composed of oligodendrocytes; in the PNS, it will be composed of Schwann cells

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10
Q

What are the two main different types of neurone?

A

Multipolar and unipolar

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11
Q

Out of multipolar and unipolar, which is the most common type of neurone?

A

Multipolar

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12
Q

How many dendrites must a neurone have to be classed as multipolar?

A

Two or more

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13
Q

Are motor neurones (either of skeletal muscle or the ANS) multipolar or unipolar?

A

Multipolar

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14
Q

Usually, where is the cell body of a multipolar neurone found?

A

In the CNS (with the axon extending into the PNS)

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15
Q

Usually the cell body of a multipolar neurone is found in the CNS. What is the exception to this?

A

In the ANS: the cell body of the presynaptic neurone is located in the CNS, but the cell body of the postsynaptic neurone is located within autonomic ganglia in the PNS

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16
Q

Are sensory neurones multipolar or unipolar?

A

Unipolar

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17
Q

Most unipolar neurones are located where?

A

In the dorsal root ganglion

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18
Q

Where is the cell body of a unipolar neurone found?

A

In the PNS

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19
Q

In a motor (efferent) neurone, where does the impulse move towards?

A

The body wall, body cavity or an organ

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20
Q

In a sensory (afferent) neurone, where does the impulse move towards?

A

The brain

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21
Q

What are nerves?

A

A collection of axons surrounded by connective tissue and blood vessels

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22
Q

What is the CNS equivalent of a nerve?

A

A tract

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23
Q

What are the two main subtypes of nerve?

A

Single modality and mixed modality

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24
Q

Which is more common - single modality or mixed modality nerves?

A

Mixed (single modality nerves are quite rare)

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25
Q

Single modality nerves can be composed of one of what modalities?

A

Somatic motor, somatic sensory, special sensory, sympathetic, parasympathetic or visceral afferent

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26
Q

All spinal nerves are which type: single or mixed modality?

A

Mixed

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27
Q

Mixed modality nerves contain what 3 modalities?

A

Somatic motor, somatic sensory and sympathetics all together in one nerve

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28
Q

How man pairs of spinal nerves are there? How are these divided up?

A

31 pairs, 8 cervical, 12 thoracic, 5 lumbar, 5 sacral and 1 coccygeal

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29
Q

What is important to remember about the cervical spinal nerves and cervical vertebrae?

A

There are only 7 cervical vertebrae so C1 starts above the first vertebrae

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30
Q

Spinal nerves are only found where in the body?

A

Intervertebral foramina

31
Q

The spinal nerves become what to travel to structures of the soma?

A

Rami

32
Q

Before they become spinal nerves, what do they travel from the spinal cord as?

A

Rootlets and roots

33
Q

Are rami single or mixed modality?

A

Mixed

34
Q

Which is larger, anterior or posterior rami?

A

Anterior

35
Q

What do anterior and posterior rami supply respectively?

A

Anterior rami supply the anterior body wall, posterior rami supply the posterior body wall

36
Q

Describe the path of a sensory axon?

A

Spinal nerve, posterior root, posterior rootlets, posterior horn of the spinal cord

37
Q

Describe the path of a motor axon?

A

Anterior horn of the spinal cord, anterior rootlets, anterior root, spinal nerve

38
Q

What is found in the dorsal root ganglion?

A

The cell bodies of primary afferent neurones

39
Q

Each spinal nerve pair supplies its particular body segment with what?

A

General sensory supply to all structures, somatic motor supply to skeletal muscles and sympathetic supply to skin and smooth muscle of arterioles

40
Q

What is a dermatome?

A

An area of skin supplied with sensory innervation from a single spinal nerve

41
Q

What is a myotome?

A

The skeletal muscles supplied with somatic motor innervation from a single spinal nerve

42
Q

Is the myotome always deep to the dermatome of the same spinal nerve?

A

No, it sometimes can be but isn’t always

43
Q

What is the dermatome level of the male nipple?

A

T4

44
Q

What is the dermatome level of the umbilicus?

A

T10

45
Q

What range of dermatomes supply the scalp, neck and shoulder?

A

C2, C3, C4

46
Q

What range of dermatomes supply the upper limb?

A

C5-T1

47
Q

What range of dermatomes supply the lower limb, gluteal region and perineum?

A

L2-S4

48
Q

What is a nerve plexus?

A

Intermingled anterior rami from a number of adjacent spinal nerves

49
Q

The anterior rami of a nerve plexus contribute to the formation of multiple what?

A

Peripheral nerves

50
Q

What spinal nerves form the cervical plexus? What does this supply?

A

C1-C4, the scalp, neck and diaphragm

51
Q

What spinal nerves form the brachial plexus? What does this supply?

A

C5-T1, the upper limb

52
Q

What spinal nerves form the lumbar plexus? What does this supply?

A

L1-L4, the lower limb

53
Q

What spinal nerves form the sacral plexus? What does this supply?

A

L5-S4, the lower limb, gluteal region and perineum

54
Q

Where does sympathetic outflow originate from? It passes down the spinal cord and exits at what spinal levels?

A

Control centres in the brain / T1-L2

55
Q

What additional feature of the spinal cord allows sympathetics to leave at T1-L2 levels?

A

Lateral horns

56
Q

The presynaptic sympathetic axons is motor innervation, so after leaving the spinal cord it passes through where to reach the spinal nerve?

A

Anterior roots and rootlets

57
Q

How does sympathetic supply reach the body wall structures?

A

Via anterior and posterior rami of spinal nerves

58
Q

How does sympathetic supply reach the thoracic viscera?

A

Cardiopulmonary splanchnic nerves

59
Q

How does sympathetic supply reach the abdominopelvic viscera?

A

Abdominopelvic splanchnic nerves

60
Q

Once sympathetics pass into the anterior and posterior rami of spinal nerves, how do they reach organs of he head and neck, and the body wall?

A

By ‘hitching a ride’ with arteries

61
Q

Describe where presynaptic sympathetic fibres would be found?

A

Leaving the spinal cord in anterior roots/rootlets

62
Q

Describe where postsynaptic sympathetic fibres would be found?

A

Within anterior and posterior rami of spinal nerves

63
Q

Where are paravertebral sympathetic ganglia found?

A

Associated with the sympathetic chain

64
Q

Where are prevertebral sympathetic ganglia found?

A

Infront of the abdominal aorta

65
Q

Do sympathetics to the heart and lungs synapse paravertebral or prevertebral sympathetic ganglia?

A

Paravertebral

66
Q

Do sympathetics to the abdomen and pelvis synapse paravertebral or prevertebral sympathetic ganglia?

A

Prevertebral

67
Q

Where do presynaptic parasympathetic axons leave the CNS?

A

CNs III, VII, IX and X, and sacral spinal nerves

68
Q

How do parasympathetics travel to the eye?

A

Via the ciliary ganglion

69
Q

How do parasympathetics travel to the lacrimal and salivary glands?

A

Via parasympathetic ganglia in the head and neck

70
Q

How do parasympathetics travel to organs of the neck chest and abdomen (to the midgut)?

A

Vagus nerve

71
Q

How do parasympathetics travel to the hindgut, pelvis and perineum?

A

Sacral spinal nerves

72
Q

Horner’s syndrome is caused by what?

A

Impaired sympathetic innervation to the head and neck

73
Q

What is the clinical picture of Horner’s syndrome?

A

Ipsilateral miosis, ptosis, anhydrosis and increased redness and warmth