(3) Spinocerebellar pathways Flashcards Preview

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Flashcards in (3) Spinocerebellar pathways Deck (47)
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1
Q

summary: posterior/dorsal column medial lemniscus pathway carries what type of sensory information (4)

A

proprioception
fine touch
pressure
vibration

2
Q

summary: anterolateral/spinothalamic pathway carries what type of sensory information (5)

A
crude touch
pressure
pain 
temperature
itch
3
Q

what are the basis of these different sensory pathways?

dorsal column and spinothalamic

A

different types of sensory receptors in skin, joints and muscle

4
Q

cutaneous receptors do what

A

mediate sensory information in (sensory) spinal cord pathways

5
Q

types of cutaneous receptors (4 sensations)

A

vibration= Pacinian corpuscle

touch= Meissner corpuscle (fine touch), Merkel endings (fine touch), endings around hairs, free nerve endings

pressure= ruffini endings

pain/temp/itch= free nerve endings

6
Q

2 touch receptors from hairy skin

A

1) receptors endings wrap around hairs

2) Merkel cell (in basal layer of epidermis)

7
Q

when skin is deformed there is a change in which receptor

A

change in merkel cell receptor onto nerve cells, and transmit to spinal cord

8
Q

where is merkel cell found, responsible for?

A
  • hair and glabrous skin

- responsible for ability to perform fine tactile discriminations with fingertips (2 pt discrimination)

9
Q

where are meissner corpuscle found

A

they are encapsulated endings in dermal papillae of hairless skin

  • layer of Schwann cells within the capsule
10
Q

where are Pacinian corpuscles found

A

subcutaneously over entire body and connective tissue sites

  • rapidly adapting
11
Q

where are ruffini endings found

A

in dermis and subcutaneously, and other connective tissue sites

  • slow adapting
12
Q

what sensory endings are found in glabrous skin?

A

fine touch: (M) meissner corpuscle, (Me) Merkel cell

vibration: (PC) Pacinian corpuscle
pressure: (R) ruffini ending

13
Q

what is 2 point discrimination

A

minimum distance by which 2 stimuli can be separated and perceived as 2 stimuli

14
Q

proprioceptors

A

another way sensory information is mediated in spinal cord pathways

15
Q

proprioception

A

perception of the position of parts of the body

16
Q

proprioceptors are derived from

A

vibration, touch and pressure receptors in skin and joints, and muscle spindles and Golgi Tendon organs at myotendinous junctions and joints

17
Q

muscles are supplied with 2 important types of encapsulated receptors

A
  • muscle spindle (unique to muscle)

- Golgi tendon organ (similar to ruffini ending- pressure)

18
Q

what is the function of muscle spindles in skeletal muscle

A

relay sensory information of proprioceptors and DETECT MUSCLE LENGTH

  • provide info about position of body in space
19
Q

muscle spindles are…

A

long, thin, stretch receptors scattered throughout striated muscle in body

20
Q

muscle spindles consist of…

A

intrafusal muscle fibers (inside the spindle)
- small muscle fiber with capsule surrounding middle 1/3 of fibers

  • ends of intrafusal muscle fibers are attached to extrafusal fibers
    (when muscle is stretched, intrafusal fibers also stretched)
21
Q

golgi tendon organ tracks…

A

TENSION developed by tendon

22
Q

how does a golgi tendon organ function

A
  • large diameter sensory fibers enter capsule and branch into fine processes that are inserted among collagent bundles
  • tension on capsule squeezes fine processes
  • resulting distortion stimulates them
23
Q

3 unconscious proprioception/sensory pathways carried by spinal cord to cerebellum via ….

A

posterior/dorsal spinocerebellar tract

anterior/ventral spinocerebllar tract

cuneocerebellar tract

24
Q

what is the function of the cerebellum

A

integration center for motor control

25
Q

9 parts to posterior/dorsal spinocerebellar tract

ascending, sensory, unconscious

A

1) proprioceptors (muscle spindles, Golgi tendon) in lower leg
2) primary sensory neuron in DRG
3) white matter of spinal cord
4) ascend in fasciculus gracilis (spinal cord)
5) synapse with dendrites of Clarke’s nucleus/nucleus dorsalis (T1-L2/L3)
6) ascend ipsilaterally in posterior spinocerebellar tract (PSCT)
7) caudal pons (lower)
8) inferior cerebellar peduncle
9) cerebellum

26
Q

origin of posterior/dorsal spinocerebellar tract

A

clarke’s nucleus

aka nucleus dorsalis

27
Q

body part –> posterior/dorsal spinocerebellar tract

A

trunk, lower extremity

remember fasciculus/nucleus gracilis

28
Q

major inputs posterior/dorsal spinocerebellar tract

A

mechanoreceptors in muscles, joints and skin

29
Q

midline crossing posterior/dorsal spinocerebellar tract

A

NONE

30
Q

peduncle used to enter cerebellum posterior/dorsal spinocerebellar tract

A

inferior cerebellar peduncle

31
Q

10 parts of anterior/ventral spinocerebellar tract

ascending, sensory, unconscious

A

1) proprioceptors (golgi tendon organs, cutaneous receptors) in lower body
2) primary sensory neuron in DRG
3) axons travel to grey matter of spinal cord
4) synapse with dendrites of spinal border cells (T12- L5)
5) axons of spinal border cells CROSS via anterior white commissure
6) ascend in anterior spinocerebellar tract (ASCT)
7) rostral pons
8) superior cerebellar peduncle
9) cerebellum (synapse)
10) CROSS beck in cerebellum

32
Q

origin anterior/ventral spinocerebellar tract

A

spinal border cells

33
Q

body part–> anterior/ventral spinocerebellar tract

A

trunk, lower extremity

34
Q

major inputs anterior/ventral spinocerebellar tract

A

mechanoreceptors, movement related interneurons

35
Q

midline crossing anterior/ventral spinocerebellar tract

A
  • spinal cord

- cerebellum

36
Q

peduncle used to enter cerebellum in anterior/ventral spinocerebellar tract

A

superior cerebellar peduncle

37
Q

8 parts to cuneocerebellar tract

ascending, sensory, unconscious

A

1) proprioceptors (muscle spindles, golgi tendon organ) in upper body
2) primary sensory neuron in DRG
3) ascend in fasciculus cuneatus
4) synpase with dendrites of lateral cuneate nucleus (in lower medulla)
5) ascend in cuneocerebellar tract (CCT(
6) caudal pons (lower)
7) inferior cerebellar peduncle
8) cerebellum

38
Q

origin cuneocerebellar tract

A

lateral cuneate nucleus (medulla)

39
Q

body part –> cuneocerebellar tract

A

trunk, upper extremity

40
Q

major inputs cuneocerebellar tract

A

mechanoreceptors in muscles, joints, skin

41
Q

midline crossing cuneocerebellar tract

A

NONE

42
Q

peduncle used to enter cerebellum in cuneocerebellar tract

A

inferior cerebellar peduncle

43
Q

cerebellar peduncles are important for??

A

circuitry

44
Q

3 cerebellar peduncles

A

SCP (superior)= predominant OUTPUT pathway
- anterior spinocerebellar tract

MCP (middle)= connect pons to cerebellum

ICP (inferior)= lower part of pons, predominant peduncle for info flowing INTO cerebellum

45
Q

lesions to spinocerebellar tracts present as…

A

ipsilateral loss of muscle coordination

  • unlikely damaged in isolation, lesions usually accompanied by injury to descending motor tracts
  • cause muscle weakness/paralysis, usually masks loss of muscle coordination
46
Q

if theres damage to spinocerebellar tracts, likely have damage to which descending pathway?

A

lateral corticospinal tract

47
Q

spinocerebellar tract damage component of hemicord lesions

A
  • vibration/pain loss RIGHT side lower body= damage to dorsal columns, loss unconscious proprioceptive info to cerebellum
  • pain/temp loss LEFT side lower body= loss of spinothalamic/anterolateral pathway
  • motor loss RIGHT side lower body= loss of corticospinal tract, or motor neurons in anterior horn