PNS Revision Flashcards Preview

Neurology > PNS Revision > Flashcards

Flashcards in PNS Revision Deck (48)
Loading flashcards...
1
Q

what is a collection of nerve cell bodies known as in the CNS and PNS?

A
CNS = nucleus
PNS = ganglion
2
Q

dendrites vs axon?

A
dendrites = carry info towards the cell body
axon = carries info away from the cell body, much longer
3
Q

what does an axon connect to?

A

another neuron or an effector cell

4
Q

Multipolar neuron?

A
  • most common
  • 2 or more dendrites
  • all motor neurones of skeletal muscle and ANS
  • cell body in CNS, axon in PNS
5
Q

Unipolar neuron?

A
double process (aka pseudounipolar as technically have 2 processes but connect to a single point)
involved in sensory function
cell body in PNS
6
Q

describe motor neurones?

A

efferent
impulse moves towards body wall, body cavity or organ
multipolar neuron

7
Q

describe sensory neurone?

A

afferent
impulses moves towards the brain
unipolar

8
Q

what are nerves?

A

collections of axons surrounded by connective tissue and blood vessels (called a tract in CNS)

9
Q

single modality nerve?

A

all axons in the nerve carry the same one of - somatic motor, somatic sensory, special sensory, sympathetic, parasympathetic or visceral afferent
“tracts” in CNS tend to be single modality

10
Q

mixed modality nerves?

A

somatic motor, somatic sensory and sympathetic all together in one nerve
(most nerves)

11
Q

12 cranial nerves?

A
ophthalmic
optic
oculomotor
trochlear
trigeminal
abducens
facial
vestibulocochlear
glossopharyngeal
vagus
spinal accessory
hypoglossal
12
Q

cranial nerve modalities?

A
sensory
sensory
motor
motor
both
motor
both
sensory
both
both
motor
motor
13
Q

where do the cranial nerves attach to the CNS?

A
forebrain
forebrain
midbrain
midbrain
pons
junction (P&Med)
junction (P&Med)
junction (P&Med)
medulla
medulla
spinal cord
medulla
14
Q

in which direction are the cranial nerves named?

A

anterior to posterior and medial to lateral

15
Q

what are the categories of spinal nerves?

A
8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal
16
Q

where are the spinal nerves found?

A

only called a spinal nerve when in the intervertebral foramina

17
Q

what do spinal nerves connect with?

A

structures of the soma via rami

the spinal cord segment of the same number via roots and rootlets

18
Q

formation and divisions of spinal nerves?

A

anterior/posterior rootlets combine to form anterior/posterior roots
anterior/posterior roots combine to form the spinal nerve
spinal nerve then splits into anterior (large) and posterior (smaller) rami

19
Q

what does the posterior rami supply?

A

posterior body wall

20
Q

what does the anterior rami supply?

A

anterolateral body wall

21
Q

spinal nerves/rami vs roots/rootlets?

A

roots/rootlets = only have one type of modality (anterior = motor, posterior = sensory)
spinal nerves/rami = all have mixed modality (somatic motor, somatic sensory and sympathetic innervation)

22
Q

what is the dorsal root ganglion?

A

swelling in posterior root where cell bodies of primary afferent neurones are found

23
Q

each spinal nerve pair supplies a body segment with what?

A

general sensory supply to all structures
somatic motor supply to skeletal muscles
sympathetic nerve supply to the skin and to the smooth muscle of arteries

24
Q

what is a dermatome?

A

area of skin supplied with sensory innervation from a single spinal nerve which also supplies sensory innervation to deeper structures

25
Q

is there any overlap in the sensory innervation of the skin of a dermatome?

A

yes innervation of skin is from adjacent spinal nerves

therefore if a dermatome is numb, more than one spinal nerve is damaged

26
Q

what is a myotome?

A

the skeletal muscles supplied with motor innervation from a single spinal nerve
may be deep to the dermatome of the same spinal nerve, but not always
(T2 - T12 tend to have the same dermatome/myotome)

27
Q

give an example of different dermatome/myotome?

A

C3,4,5
dermatome = shoulder and upper arm
myotome = diaphragm

28
Q

dermatome landmarks?

A
nipple = T4 segment
umbilicus = T10
29
Q

dermatomes of posterior scalp, neck and shoulder?

A

C2-4

30
Q

upper limb dermatomes?

A

C5-T1

31
Q

lower limb, gluteal region and perineum dermatomes?

A

L2-Co1

32
Q

what are nerve plexuses formed of?

A

intermingled ANTERIOR rami from a number of adjacent spinal nerves

33
Q

what makes up the cervical plexus?

A

C1-C4

posterior scalp, neck and diaphragm

34
Q

brachial plexus?

A

C5-T1

upper limb

35
Q

lumbar plexus?

A

L1-L4

lower limb

36
Q

sacral plexus?

A

L5-S4

lower limb, gluteal region and perineum

37
Q

describe sympathetic outflow?

A

originates from control centres in the brain

passes down spinal cord and exits via T1 - L2

38
Q

why can sympathetic outflow only exit via T1 - L2?

A

only they have lateral horns which contain cell bodies with presynaptic sympathetic axons

39
Q

what is sympathetic innervation? what does this mean for outflow?

A

motor innervation

means it has to come from anterior roots/rootlets

40
Q

what are the 4 possible routes of exit from the spinal cord for sympathetic outflow?

A
  1. ascend and then synapse
    Synapse at level of entry
  2. Descend then synapse
  3. Pass through sympathetic trunk without synapsing to enter an abdominopelvic splanchnic nerve
41
Q

sympathetic innervation is present in all spinal nerves, true or false?

A

true

just takes different routes to get into the nerves

42
Q

paravertebral ganglia?

A

sympathetic chain

43
Q

Sympathetic outflow to the heart?

A

presynaptic axons synapse in T1 or cervical paravertebral ganglia
postsynaptic axons then pass in cardiopulmonary splanchnic nerves to the SA and AV nodes in myocardium

44
Q

lungs sympathetic outflow?

A

presynaptic axons synapse in upper thoracic paravertebral ganglia
postsynaptic axons pass in cardiopulmonary splanchnic nerves to the bronchiolar smooth muscle and mucous glands

45
Q

abdominopelvic organs sympathetic outflow?

A

presynaptic axons synapse in one of the prevertebral ganglia (outside of the spinal column)

46
Q

adrenal medulla sympathetic outflow?

A

presynaptic axons pass through the aorticorenal ganglion to synapse directly onto the adrenaline/noradrenaline secreting cells of the adrenal medulla

47
Q

describe parasympathetic outflow?

A

presynaptic axons leave the CNS via cranial nerves 3, 7, 9, 10 and sacral spinal nerves then travel via:

  • ciliary ganglion (eye)
  • parasympathetic ganglia in head (lacrimal/salivary glands)
  • vagus nerve (organs between neck and mid-gut)
  • sacral spinal nerves (hind-gut to perineum)
48
Q

why do symptoms occur in horners syndrome?

A

no sympathetic innervation to the dilator pupillae = miosis
no innervation to LPS = droopy eyelid (ptosis)
no innervation to sweat glands = reduced sweating
reduced innervation to arterioles = dilation = increased warmth and redness