Lecture 3b-ascending pathways Flashcards Preview

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Flashcards in Lecture 3b-ascending pathways Deck (50)
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1

In the ascending pathways, sensory info from receptors comes into the cord via what?

what are their steps after that?

peripheral nerves/spinal nerves/dorsal roots

1. the info participates in spinal reflexes or
2. ascends to the cerebral cortex and
3. ascends to the cerebellum

2

in the descending pathway, motor commands issued by your brain descend to the cord to synapse wehre?

cord's ventral horn cells

3

where do tracts live

white matter

4

many tracts have 2 part names, what does the first part tell you? what about the second?

1. tells you the location of the neuronal cell bodies from which these axons originated from (aka cell bodies of origin)
2. tells you the site where they terminate (aka synapse)

5

whta are the 3 kinds of connections that afferent info make up

1. local reflex connections
2. connections destined for the cerebral cortex (conscious perception)
3. connections destined for the cerebellum (regulation of muscle tone and coordination of muscle function; subconscious)

6

what is proprioception? what can it be?

body sense
either conscious or unconscious

7

what do conscious sensation reach? via what?

what does unconscoius sensations refer to?

the cerebral cortex via thalamus

unconscious sensations refers to stuff that does not

8

what are the different subtypes of touch (tactile) stimuli?

2 point tactile discrimination
light(gross) touch
pressure
vibration

9

what is epicritic
what is protopathic

discriminating touch
pain and temperature

10

in the ascending pathway, where does the 1st order neuron always have its cell body in. why?

dorsal root ganglion
-there are no synapses in the DRG

11

the shortest path to the cerebral cortex is 3 neurons long, what are they?

primary afferent
neuron that crosses the midline
thalamic neuron

12

where does each primary afferent neuron have its cell body in?

sensory ganglion (DRG)
-a peripherally directed process ending in skin, muscle, or a joint, and a central process ending in the CNS

13

primary afferents terminate in the CNS on...

2nd order neurons, which in turn project to 3rd order neurons and so forth.

14

with few exceptions, the receptive ending, cell body, and central terminals of a primary afferent are all on the...

same side
-central process ends on the side ipsilateral to the cell body

15

somatic sensory afferents segregate at the margin of the spinal cord.
where do large diameter heavily myelinated fibers enter? and where?

small diamter fibers? and wehre?

medially through dorsal funiculus
Mylinated=Medial

laterally through the zone of Lissauer
Lissauer's=Later

16

fasciculus gracilis and cuneatus entering ____ to lissaurer's tract;
-2 pt tactile and proprioceptive info comes in more ______ and is highly myelinated whereas pain and temp is ______ myelinated

medial
medially
thinly

17

what general sensations do the medial lemniscus pathway in the dorsal column carry

"conscious proprioception" from the lower extremity =>eventually lead to cerebral cortex

proprioception (joint position)
2-point tactile discrimination
pressure
vibratoin

18

what is the dorsal column- medial lemniscus pathway (lower extremity)?

1. 1st cell body is DRG enters the cord medially
2. once in dorsal columns (funiculus) rise as fasciculus gracilis
3. FG synpase at nucleus gracilis (2nd CB)
4. 2nd order neuron sneds out fibers (INTERNAL ARCUATE) to arc around and cross the midline to the other side of the body. aka SENSORY DECUSSATION
5. fibers rise as medial lemniscus
6. 3rd order fibers leaving the thalamus as sent through the internal capsule (through its post limb)
7. arrive at the specific place for legs w/in somatosensory area of the parietal cortex

19

what are mechanoreceptors

more superficial
pacinian corpuscles (vibration)
meissner's corpuscles (tactile discrimination)

20

what are proprioceptors

for position sense
more deep
muscle spindles
gogli tendon worgan

21

where does tactile sensation start

skin receptors

22

where does proprioception start out w/

specilized receptors in the muscle spindles or tendons

23

after leaving the receptors, what is afferent info sent via

large myelinated fast conducting nerves

(same primary afferent as monosynaptic stretch reflex)

24

where are the central branches of the axons of the primary sensory neurons for discriminative touch and proprioception located

medially located in each rootlet and bifurcate on entering the dorsal funiculus

25

if epicritic sensation is blocked below/before the decussation, wehre is the clinical deficit to the lesion?
what if it the lesion if above the decussation?

ipsilateral

contralateral

26

what is romberg sign

loss of conscious proprioception
-ex. walking requires a sense wehere you are in space, if a conscious joint position sense from the lwoer body were damaged and you close your eyes you would sway bc no sense of where you are

27

what is 2 point discrimination

pt asked to determine whether two points of an instrument are touching them or only 1. most accurate place is at fingertips

28

what is vibratory sense and deep pressure sense

to test vibratory sense a turning fork is placed against a joint

29

does FG ever cross over to the other side?

no

30

what is the dorsal column- medial lemniscus pathway (upper extremity)?

entry at T6 or above
Lumar entry

1. 1st cell body is DRG enters the cord medially
2. once in dorsal columns (funiculus) rise as fasciculus cuneatus
3. FG synpase at nucleus cuneatus (2nd CB)
4. 2nd order neuron sneds out fibers (INTERNAL ARCUATE) to arc around and cross the midline to the other side of the body. aka SENSORY DECUSSATION
5. fibers rise as medial lemniscus
6. 3rd order fibers leaving the thalamus as sent through the internal capsule (through its post limb)
7.synapses on post-central gyrus in parietal complex arrive at the specific place for legs w/in somatosensory area of the parietal cortex