Clinical Anatomy of Spinal Nerves and Testing Flashcards

1
Q

Describe what dermatomes are?

A

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

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2
Q

If you damage a spinal nerve why may you not lose complete sensation to the corresponding dermatome?

A

innervation of skin by adjacent spinal nerves shows overlap (so you would have to damage the nerves above and below too!)

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3
Q

Describe what myotomes are?

A

the skeletal muscles supplied with motor innervation from a single spinal nerve
may be deep to dermatome of same spinal nerve, but not always

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4
Q

Does C1 have a dermatome?

A

No

can’t determine as up to 50% of the population don’t have posterior rootlets in the C1 spinal cord segment

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5
Q

What are two landmarks for trunk segmentation of dermatomes?

A
  • Nipple = T4 segment

- Umbilicus = T10 segment

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6
Q

Describe limb, neck and shoulder segmentation for dermatomes?

A

Posterior scalp, neck and shoulder = C2-C4
Upper limb = C5-T1
Lower limb, gluteal region and perineum = L2-Co1

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7
Q

Describe the places you can test sensation in the C2-C8 dermatomes?

A
C2 – back of scalp & Adam’s apple
C3 – back of neck & jugular notch
C4 – clavicle & shoulder tip
C5 – “badge patch”
C6 – thumb
C7 – middle finger
C8 – little finger
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8
Q
Describe the places you can test
T1
T2
T4
T8
T10
T12
A
T1 – medial forearm
T2 – medial arm & sternal angle
T4 – nipple
T8 – xiphoid process
T10 – umbilicus
T12 – pubic symphysis
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9
Q

Describe the places you can test the L1-L5 dermatomes?

A
L1 – groin 
L2 – anterior thigh
L3 – anterior knee
L4 – medial malleolus
L5 – dorsum of foot
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10
Q

Describe the places you can test the S1-S5 dermatomes?

A
S1 - heel
S2 – posterior knee
S3 - buttock
S4 - perineum
S5 – perianal skin
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11
Q

Describe how you test true dermatomes vs peripheral cutaneous nerves and how you may determine where the problem is?

A

If you test a peripheral nerve that has 3 true dermatomes, then when you test the area of that nerve of one dermatome it is only that spinal root being stimulated.

So if you have lost sensation across all the dermatomes in the nerve’s area that suggests there is an issue lower down with the nerve. However if you have lost sensation only in one dermatome area then that suggests a problem at the spinal nerve root.

Because if the roots combine lower down if you knock out the nerve then all areas are knocked out but if you knock out one root of the nerve higher up the other parts of the nerve still work.

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12
Q

Cervical plexus is from roots _______ and supplies _____

A

cervical plexus (C1-C4):
neck postural & strap muscles
diaphragm

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13
Q

Brachial plexus is from roots ______ and supplies __________

A

brachial plexus (C5-T1):
muscles of the upper limb
extrinsic back muscles

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14
Q

Intrinsic back muscles, anterolateral abdominal wall and intercostal muscles are supplied by which nerve roots?

A

T2-L3

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15
Q

The lumbosacral plexus is from roots ________ and supplies ________

A

lumbosacral plexus (L1-S4):
muscles of the lower limb
perineal skeletal muscles

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16
Q

How do you test the C5 and C7 myotomes with shoulder movements?

A

At the shoulder

  • abduction – C5,
    deltoid
  • adduction - C7,
    pec major & lat.
    dorsi
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17
Q

How do you test the C7-T1 myotomes with finger movements?

A

At the finger joints

- flexion – C8,  
                digit flexors
 - extension – C7, 
               digit extensors
- abduction – T1,  
                dorsal interossei
 - adduction – T1, 
               palmar interossei
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18
Q

How do you test the C5-C8 myotomes with elbow movements?

A

At the elbow joint

  • flexion – C5, C6,
    biceps brachii
  • extension - C7, C8,
    triceps brachii
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19
Q

How do you test the C6 and C7 myotomes at the wrist joint?

A
  • flexion – C6, C7,
    carpal flexors
  • extension – C6, C7,
    carpal extensors
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20
Q

Abduction at the shoulder is testing what myotome?

A

C5

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21
Q

Adduction at the shoulder is testing what myotome?

A

C7

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22
Q

Flexion of the digits is testing what myotome?

A

C8

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23
Q

Extension of the digits is testing what myotome?

A

C7

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24
Q

Abduction and adduction of the digits is testing what myotome?

A

T1

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25
Q

Flexion of the elbow joint is testing what myotomes?

A

C5 and C6

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26
Q

Extension of the elbow joint is testing what myotomes?

A

C7 and C8

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27
Q

Flexion and extension of the wrist is testing what myotomes?

A

C6 and C7

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28
Q

How do you test the L2 and L3 myotomes at the hip joint?

A
  • flexion – L2, L3,

psoas major

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29
Q

How do you test the L5 and S1 myotomes at the hip joint?

A
  • extension - L5, S1

glut. max & hamstrings

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30
Q

How do you test the L5 and S1 myotomes at the knee joint?

A
  • flexion – L5, S1,

hamstrings

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31
Q

How do you test the L3 and L4 myotomes at the knee joint?

A

extension – L3, L4

quadriceps

32
Q

How do you test the L4 and L5 myotomes at the ankle joint?

A
  • dorsiflexion- L4, L5,

tibialis anterior

33
Q

How do you test the S1 and S2 myotomes at the ankle?

A
  • plantar flexion - S1, S2

gastrocnemius/soleus

34
Q

How do you test the L4 myotome at the ankle?

A

inversion- L4,

tibialis ant. & post.

35
Q

How do you test the L5 and S1 myotome at the ankle?

A
  • eversion - L5, S1,

fibularis longus & brevis

36
Q

Flexion of the hip tests what myotomes?

A

L2, L3

37
Q

Extension of the hip tests what myotomes?

A

L5, S1

38
Q

Flexion of the knee joint tests what myotomes?

A

L5, S1

39
Q

Extension of the knee joint tests what myotomes?

A

L3, L4

40
Q

Dorsiflexion of the ankle tests what myotomes?

A

L4, L5

41
Q

Plantar flexion of the ankle tests what myotomes?

A

S1, S2

42
Q

Inversion of the ankle tests what myotomes?

A

L4

43
Q

Eversion of the ankle tests what myotomes?

A

L5, S1

44
Q

Describe the difference between peripheral nerve testing and myotome testing and what is stimulated?

A

So if you want to move the myotome area of L3 the AP moves up through the femoral nerve but it reaches the spinal cord at L3 level.

45
Q

Describe the pathway of a reflex using the patellar reflex as an example?

A

1) patellar ligament tapped
2) stretches quadriceps fibres
3) muscle stretch receptors initiate APs in anterior rami within femoral nerve
4) sensory APs conducted to dorsal horn of L4
axons pass into anterior horn to synapse directly on LMNs that supply quadriceps
5) APs conducted via LMN axons in femoral nerve to reach quadriceps NMJ
muscle contracts to extend knee joint

so it’s monosynaptic because the sensory neurons synapse directly onto the lower motor neuron

46
Q

Reflex pathways can be described as ________

A

monosynaptic

47
Q

List five stretch reflexes and what nerve roots they are testing?

A
Biceps C5 (C6)
Supinator/ brachioradialis C6
Triceps C7
Knee L4
Ankle S1
48
Q

Describe muscle paralysis and what it would look like on examination?

A

a muscle without a functioning motor nerve supply is “paralysed”

a paralysed muscle cannot contract

on examination the muscle would have reduced tone

49
Q

Describe muscle spasticity and what it would look like on examination?

A

the muscle has an intact and functioning motor nerve

the descending controls from the brain are not working

on examination the muscle would have increased tone

50
Q

Muscles of facial expression are innervated by?

A

Facial Nerve

51
Q

Muscles of mastication are innervated by?

A

Mandibular Division of the Trigeminal Nerve

52
Q

Muscles of the tongue (minus palatoglossus) are innervated by?

A

Hypoglossal nerve

53
Q

Muscles of the soft palate are innervated by?

A

Vagus nerve/ pharyngeal plexus

54
Q

Neck postural muscles are innervated by?

A

Posterior rami of cervical spinal nerves

55
Q

Strap muscles are innervated by?

A

Cervical plexus

56
Q

Diaphragm is innervated by?

A

Phrenic nerve (anterior rami of C3,4 and 5 from cervical plexus)

57
Q

Sternocleiomastoid and trapezius are innervated by?

A

The spinal accessory nerve

58
Q

Muscles of the pharynx are innervated by?

A

The vagus nerve (mainly)

59
Q

Intrinsic muscles of the larynx are innervated by?

A

The vagus nerve (mainly)

60
Q

The intercostal muscles are innervated by?

A

intercostal nerves

61
Q

Anterolateral abdominal wall muscles are innervated by?

A

Thoracoabdominal nerves

62
Q

Erector spinae and transversospinalis are innervated by?

A

Posterior rami of spinal nerves

63
Q

Deltoid and teres minor are innervated by?

A

Axillary nerve (C5, C6)

64
Q

Anterior compartment of the arm is innervated by?

A

musculocutaneous nerve

65
Q

Anterior compartment of the forearm minus medial half of flexor digitorium profundus and flexor carpi ulnaris is innervated by?

A

median nerve

(C5), C6,7,8,T1

66
Q

The thenar muscles of the hand and lateral two lumbricals are innervated by?

A

median nerve

(C5), C6,7,8,T1

67
Q

Posterior compartment of the arm and forearm is innervated by?

A

radial nerve (C5),C6,7,8,(T1)

68
Q

Flexor carpi ulnaris, lateral half of flexor digitorum profundus and the intrinsic hand muscles (minus thenar and 2 lumbricals) is innervated by?

A

ulnar nerve C(7),C8,T1

69
Q

The anterior compartment of the thigh is innervated by?

A

The femoral nerve (L2, 3, 4)

70
Q

The true hamstrings and the posterior leg are innervated by?

A

The tibial nerve (L4-S3)

71
Q

The medial compartment of the thigh is innervated by?

A

The obturator nerve (L2, L3, L4)

72
Q

The short head of biceps femoris is innervated by?

A

common fibular nerve (L4-S2)

73
Q

The lateral leg compartment is innervated by?

A

Superficial fibular nerve

74
Q

The anterior compartment of the leg is innervated by?

A

Deep fibular nerve

75
Q

From the five terminal branches of the brachial plexus name the nerve roots each is derived from?

A
Musculocutaneous- C5, 6
Axillary- C5, 6
Radial- C5,6,7,8 and T1
Median-C5,6,7,8 and T1
Ulnar C8 and T1