Module D-02 Flashcards Preview

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Flashcards in Module D-02 Deck (63):
1

What are the 5 somatosensory modalities?

Touch, vibration,proprioception(muscular),pain and temperature

2

What type of neurons are the somatosensory receptor neurons?

Pseudounipolar

3

Where are sensory endings of the somatosensory receptor neurons found?

In skin or in (close to) muscle

4

Where are cell bodies of the somatosensory receptor neurons found?

Dorsal root and Cranial nerve Ganglia

5

What are the 2 Cutaneous touch receptors?

1)Merkel’s disks
2)Ruffini’s endings

6

What type of specific touch is transduced by Merkel's disks?

discriminative touch

7

What type of specific touch is transduced by Ruffini’s endings?

skin stretch

8

What are the 2 Cutaneous receptor specific for Vibration?

1) Meissner's corpuscles
2) Pacinian corpuscles

9

What type of vibration do Meissner's corpuscles have highest sensitivity?

highest sensitivity / lowest threshold for lower frequencies of about 50 Hz

10

What type of vibration do Pacinian corpuscles have highest sensitivity?

highest sensitivity / lowest threshold for higher frequencies of about 300 Hz

11

What type of receptors transduce the signal for pain and temperature?

Free nerve endings

12

What type of free nerve endings for prickling pain and burning pain?

- pricking pain by rapidly adapting mechano-sensitive or thermo-sensitive receptors,
- burning pain by slowly adapting polymodal receptors

13

What type of free nerve endings for Temperature?

Cold and warm receptors

14

What type of receptors transduce proprioception (position sense)?

Proprioceptors:
Muscle spindles and Golgi tendon organs

15

Where are muscle spindles found?

Embedded in extrafusal fibers of working musculature

16

What type of receptor are the primary receptor of muscle spindle ?

Rapidly adapting receptor with a 1a afferent fiber

17

Which receptor for deep tendon reflex(myotatic reflex)?

Ia afferent fiber

18

What type of receptor is the secondary receptor of a muscle spindle?

slowly adapting receptor class II afferent fiber

19

What type of info does the primary muscle spindle fiber (1a)transduce?

Stretch

20

What type of info does the secondary muscle spindle fiber (class II) transduce?

Muscle length

21

Where are golgi tendon organs located?

border between muscle and tendon

22

What type of receptor is the golgi afferent fiber?

1b

23

What do the 1b fiber form?

afferent limb of inverse myotatic reflex

24

Afferent fibers from proprioceptors form which important pathways to the cerebellum ?

dorsal and ventral spinocerebellar tracts (don't reach consciousness)

25

Somatosensory receptors use four different fiber types:

1)Large myelinated fibers (muscle 1 and cutaneous A alpha)
2)medium myelinated fibers (muscle II and cutaneous A beta)
3) small myelinated fibers (muscle III and cutaneous A delta)
4) unmyelinated fibers (muscle IV and cutaneous C)

26

Size and conduction velocity of Large and medium myelinated fibers

diameters : up to 20 μm
conduction velocities : up to 120 m/sec

27

What type of receptors use Large and medium myelinated fibers?

cutaneous mechanoreceptors and proprioceptors

28

What type of sensory info do Large and medium myelinated fibers carry?

touch, vibration and proprioception

29

Size and conduction velocity of small myelinated fibers

diameters: about 1 μm
conduction velocities : 5 m/sec

30

Size and conduction velocity of unmyelinated fibers

diameter: 0.2 and 1.5 μm
conduction velocities: from about 0.5 to about 2 m/sec.

31

What type of sensory info do small myelinated and unmyelinated fibers carry?

pain and temperature

32

Between which vertebrae does the T1 spinal nerve emerge?

btw T1 and T2

33

At what level does the spinal cord end?

L1/L2

34

The sensory and motor nerve roots that are below L1/L2 form the___________

cauda equina

35

Dermatome for back of the head

C2

36

Dermatome for thumb

C6

37

Dermatome for Middle finger

C7

38

Dermatome for Little finger

C8

39

Dermatome for Nipple line

T4

40

Dermatome for Umbilicus

T10

41

Dermatome for Groin

L1

42

Dermatome for big toe

L5

43

Dermatome for Little toe

S1

44

Which pathway carries Touch, vibration and proprioception ?

the dorsal column/ medial lemniscus system

45

Which pathway carries Pain and Temperature?

anterolateral system (aka spinothalamic tract)

46

Describe the pathway of fibers going in the Dorsal column/medial lemniscus system.

Fibers of the dorsal root ganglion neurons => enter the dorsal column => ascend within this white matter tract(cuneate and gracile fasciculus) => to the medulla => synapse in the nuclei of the dorsal columns (cuneate and gracile nucleus).

47

Fibers that ascend in the cuneate fasciculus originate from________

Upper extremities

48

Fibers that ascend in the Gracile fasciculus originate from________

Lower extremities

49

Describe the 2 pathways of afferent pain and temp. fibers for Anterolateral system

1) Anterolateral tract:
Enter the spinal cord segments via the dorsal roots of the spinal nerves => central axons of dorsal root ganglion neurons => synapse within the dorsal horn => axons of the second order neurons cross to the contralateral side through the anterior white commissure => ascend in the ALS fiber tract of the spinal cord (white matter)

2) Collateral fibers also go up the dorsolateral tract -Lissauer's Tract

50

Where are pain and temp second order fibers from the arm ascend in the anterolateral column?

Medially

51

Where are pain and temp second order fibers from the leg ascend in the anterolateral column?

laterally

52

Where does Lissauer's tract go?

collaterals of the primary afferent fibers may ascend (or descend) one or two segments in the dorsolateral fasciculus
- divergent fibers that synapse on multiple neurons

53

What virus does Shingles originate from?

Herpes zoster

54

Describe the symptoms of shingles

painful skin irritations in the dermatomal area innervated by the related ganglion

55

Where does the herpes zoster virus stay when latent?

in dorsal root ganglion cells or trigeminal ganglion cells

56

What is Brown Sequard Syndrome?

Hemisection of the spinal cord as a result of a slow growing
mass, or a traumatic lesion interrupting ascending and descending fibers on one side of the cord causing both sensory and motor losses

57

Key sensory finding in Brown Sequard syndrome

Touch, vibration and proprioception are lost on one side of the body, whereas pain and temperature are lost on the other side of the body

58

What are the sensory findings AT the level of the lesion in Brown Sequard syndrome?

Ipsilateral side (lesion side): Loss of all 5 somatosensory
modalities
Contralateral side: none are lost

59

What are the sensory findings BELOW the level of the lesion in Brown Sequard syndrome?

Ipsilateral side (lesion side): loss of touch, vibration and
proprioception (which started at
the level of the lesion)
continues through all
dermatomes below
Contralateral side: pain and temperature sensations are all
lost except one or two segments that
may be spared due to Lissauer's tract

60

Which tract is found in the Lateral column?

Corticospinal Tract

61

What is Syringomyelia?

pathologic enlargement of the central canal of the spinal cord, that interrupts the fibers of the anterior commisure

62

What are the sensory losses AT the level of the lesion in Syringomyelia?

Bilateral: Loss of only Pain and temp

63

What are the sensory losses Below the level of the lesion in Syringomyelia?

Bilateral: No losses