Somatosensory System/ Ascending Tracts Flashcards Preview

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Flashcards in Somatosensory System/ Ascending Tracts Deck (97):
1

What are the 4 modalities of the somato-sensory system?

- Discriminative Touch
- Proprioception
- Nociception
- Temperature

2

What is divergent neural proccessing?

- Potential spreads to more than 1 system
- The axon gives off collaterals

3

What is the purpose of convergence?

To increase the contrast of the neural signal

4

What is the term for contrast enhancement ?

- Lateral inhibition

5

What are the 3 types of lateral inhibition?

- Feed forward
- Feedback
- Distal

6

What is feedforward control?

Lateral collaterals activate inhibitory cell off of primary neuron provide stimulation to inhibitory neurons. (no feedback)

7

What is local feedback inhibition?

Collaterals from inhibitory neurons receiving strong sensory input synapse on interneurons and inhibit analogous/ neighboring inhibitory neurons to better pinpoint the source of the stimulus.

8

What is distal feedback inhibition?

Axons from the motor and sensory areas of the cerebral cortex synapse on an interneuron that synapses on an inhibitory neuron targeting the secondary neurons of a somatosensory system, further inhibiting weaker input,

9

What is the overall purpose of convergence/ contrast enhancement?

- Inhibit weaker signals for stronger clarity of the more powerful sensory information

10

What is kinesthetic and position sense considered mysterious?

- We are unaware of it since it has no defined sensation that is identifiable

11

What 3 types of receptors combine to form awareness of joint position? What other signal contributes? Which is the primary receptor?

- Muscle spindles (primary)
- Skin/ SA ruffini endings
- Joint receptors (detect end of motion)
- Signals of central origins sense effort or will

12

Why are position and movements of joints separate senses?

- They share the same receptors, but central processing occurs in the different areas/ pathways

13

What 2 receptors are especially important in determining joint position?

- SA cutaneous receptors
- Tonic muscle spindles

14

What 3 receptors are especially important in determining movement?

- FA receptors
- Muscle spindles
- Golgi tendon organs

15

Where are receptors found for touch and pressure?

In the skin

16

What are the 3 primary sensory afferents for touch and pressure?

- Group II fast
- Group III and IV slow

17

Where is the origin of the fasciculus gracilis?

The dorsal root ganglions of T7 - S5

18

Do the fibers of the fasciculus gracilis cross?

No.

19

Where is the tract of the fasciculus gracilis found?

- Throughout the entire spinal cord

20

On what does the fasciculus gracilis synapse in the higher centers?

- The nucleus gracilis in medulla

21

What sensations run through the fasciculus gracilis?

- Conscious proprioception, discriminative touch, pressure, 2 point discrimination, kinesthetic sense

22

Where is the origin of the fasciculus cuneatus?

- Dorsal root ganglions of C1- T6

23

Do the fibers of the fasciculus cuneatus cross the spinal cord?

No.

24

Where is the tract of the fasciculus cuneatus found in the spinal cord?

Above T6

25

What does the fasciculus cuneatus synapse on in the higher centers?

- The nucleus cuneatus in the medulla

26

What sensations run through the fasciculus cuneatus?

- Consious proprioception, discriminative touch, pressure, 2 point discrimination, kinesthetic sense

27

What is the origin of the spinocervical thalamic tract?

- The lateral cervical nuclei of the dorsal horn (at C1, and above)

28

Do the fibers of the spinocervical thalamic tract cross?

Yes

29

What do the fibers of the spinocervical thalamic tract synapse on in the higher centers?

- Thalamus

30

What sensation runs through the spinocervical thalamic tract?

- Discrimitive touch
- Passive manipulation (somewhat)

31

What fascicle is the spinocervical thamalic tract analgous to?

- The fasciculus cuneatus (maybe?)

32

What is the origin of dorsal spinocerebellar tract?

- Laminae 7/ Clark's Column of T1 - L2

33

What is Clark's Column

- Ias, Ibs, and IIs, give off collaterals to interneurons, which exit the horn laterally and ascends up from the lateral portion of the spinal cord

34

Do the fibers of the dorsal spinocerebellar tract cross?

- No

35

Where do the dorsal spinocerebellar tracts synapse?

On the nuclei in L3 - C1

36

Where are the dorsal spinocerebellar tracts found in the spinal cord?

- Fibers are found throughout

37

What sensory information runs through the dorsal spinocerebellar tract?

- Ia, Ib, and II fiber propriception
- UNCONCIOUS proprioception

38

Where does the ventral spinocerebellar tract originate?

- Laminae 5 - 7 of L3 - L5 (Spinal border cells)

39

Do the fibers of the ventral spinocerebellar tract cross?

They double cross (in the spinal cord and cerebellum??), and end up on the same side

40

Where do the primary fibers of the ventral spinocerebellar tract synapse on their nuclei?

- L1 - S5

41

Where are fibers from the ventral spinocerebellar tract found in the spinal cord?

- Throughout the spinal cord

42

Where do the fibers of the ventral spinocerebellar tract synapse in the upper centers?

- The cerebellum

43

What fibers create the ventral spinocerebellar tracts?

- Ib, FRA from WRF

44

What sensory information travels through the ventral spinocerebellar tracts?

- Unconcious proprioception
- Movement
- Posture

45

Where does the cuneocerebellar tract originate?

- The accesory cuneate nucleus (collateral off fasciculus cuneatus)

46

What is the cuneocerebellar tract an analogue to?

- The dorsal spinocerebellar

47

Do the fibers of the cuneocerebellar tract cross?

No

48

Where are the fibers found of the cuneocerebellar tract found in the spinal cord?

- They are not present

49

On what structure does the cuneocerebellar tract synapse in the higher centers?

The cerebellum

50

What fibers make up the cuneocerebellar tract?

- Ia, Ib, and Grade II

51

What sensation runs through the cuneocerebellar tract?

- Ia, Ib, II proprioception
- Unconcious proprioception

52

Where does the rostrocerebellar tract originate?

- Laminae 7 of C4- C8

53

Do the fibers of the rostrocerebellar tract cross?

No

54

Where does the rostrocerebellar tract synapse in the higher centers?

On the cerebellum

55

What fibers make up the rostrocerebellar tract?

Ib, FRA from WRF

56

What sensory information travels through the rostrocerebellar tract?

- Unconcious proprioception
- Movement
- Posture

57

Which tracts location is not currently known?

Rostrocerebellar tract

58

How are the funiculi of the dorsal horn arranged?

- Somatotopically arranged
- Sacral to lumbar to thoracic to cervical from medial to lateral

59

Where does the spinoreticular tract originate?

- Posterior horn

60

Do the fibers of the 1st spinoreticular tract cross?

No

61

Where are fibers from the spinoreticular tract found in the spinal cord?

Throughout

62

What does the spinoreticular tract synapse on in the higher centers? (tract 1 and 2)

1: Medulla reticular formation
- Giganto and lateral reticular nucleus
2: Pons reticular formation
- Reticular pontis caudalis

63

What is the function of the 1st spinoreticular tract?

- Unconcious proprioception

64

What is the function of the 2nd spinoreticular tract?

- Maintanence of the state of conscioiusness

65

What is the origin of the spinovestibular tract?

- Dorsal root ganglia

66

Do the fibers of the 2nd spinoreticular tract cross?

Yes

67

Do the fibers of the spinovestibular tract cross?

Ues

68

What does the spinovenstibular tract synapse on in the higher centers?

- Vestibular nuclei

69

What sensation travels through the spinovestibular tract?

- Ia, Ib, II proprioception
- Unconcious proprioception

70

What is the origin of the spino-olivary tract?

- Dorsal root ganglia

71

Do the fibers of the spino-olivary tract cross?

Sometimes

72

Where are the fibers of the spino-olivary tract found?

C1 - C8

73

Where do the fibers of the spino-olivary tract synapse in the higher centers?

- Inferior olivary nucleus

74

What sensation travels through the spino-olivary tracts?

- Unconscious proprioception of the neck

75

What is the origin of the spinocortical tract?

Unknown

76

Do the fibers of the spinocortical tract cross?

No

77

Where are the fibers of the spinocortical tract found in the spinal cord?

Throughout

78

Where do the fibers of spinocortical tract synapse in the higher centers?

The cerebral cortex

79

What is the origin of the spinocervical tract?

Lamina III and IV

80

What is another name for the spinocervical tract?

- Morin's tract

81

Do the fibers of the spinocervical tract cross?

No

82

Where do the fibers of the spinocervical tract synapse in the higher centers?

The lateral cervical nucleus

83

What sensation travels through the spinal cervical tract?

- Concious proprioception
- Tactile sensation

84

What are the 6 minor ascending tracts?

- Spinoreticular
- Spinoreticular
- Spinovestibular
- Spino-olivary
- Spinocortical
- Spinocervical/ Morin's

85

What are the 3 interspinal reflex tracts?

- Fasciculus Septomarginalis
- Fasciculus Interfascicularis
- Fasciculus Proprius 1

86

Where does the fasciculus septomarginalis orginate from?

- The dorsal root ganglia

87

Do the fibers of the fasciculus septomarginalis cross?

- No

88

Where are the fibers of the fasciculus septomarginalis found?

L1 - S5

89

Where do the fibers of the fasciculus septomarginalis, and other interspinal reflex tracts synapse?

- On interneurons
- ACh endplates

90

What sensation travels through the fasciculus septomarginalis, and other interspinal reflex tracts?

- Proprioception interspinal reflexes

91

Where do the fibers of the fasciculus interfascicularis orginate?

The dorsal root ganglia

92

Do the fibers of the fasciculus interfascicularis cross?

No

93

Where are the fibers of the fasciculus interfascicularis found?

- C1 - T12

94

What type of sensory information travels trhough the fasciculus interfascicularis?

Proprioception Interspinal Reflexes

95

Where does the fasciculus proprius 1 originate?

- Dorsal root ganglia
- Laminae III and IV

96

Do the fibers of the fasciculus proprius 1 cross?

Probably; not sure

97

Where are the fibers of the fasciculus proprius 1 found in the spinal cord?

Throughout