Part 5: Spinal cord pathways Flashcards
1
Q
spinal cord is a ____ (descr.)
A
cylindrical cable of pathways to & from brain and rest of the body
2
Q
spinal cord extends from ____ to ____
A
base of the skull (medulla) to L1-L2 vertebrae
3
Q
spinal cord vs vertebral column
A
vertebral column extends to coccyx but spinal cord ends at L1-l2 vertebrae
4
Q
plexus is a ___
A
collection of nerves
5
Q
two plexus in spinal cord
A
-cervical (brachial plexus)
-lumbar (lumbosacral plexus)
6
Q
what covers the spinal cord?
A
-meninges
7
Q
central canal of spinal cord is _____
A
continuous with ventricles of brain
8
Q
conus medullaris (def.)
A
-tapered, lower end of the spinal cord at L1-L2
9
Q
cauda equina (def.)
A
spinal nerves continue to branch out diagonally (looks like horse tail)
10
Q
spinal cord ends at ____
A
conus medullaris at L1-L2
11
Q
filum terminale
A
fibrous tissue downward from the apex of the conus medullaris to coccyx (stabilize lower part)
12
Q
in spinal cord, grey mater is _____
A
in the inner layer
13
Q
dorsal horn is at ___
A
back
14
Q
ventral horn is at ____
A
front
15
Q
sensory at ___ horn
A
dorsal
16
Q
motor at ___ horn
A
ventral
17
Q
sympathetic at ___ horn
A
lateral
18
Q
cervical part of spinal cord: grey matter vs white matter
A
equal amounts due to cell bodies and large amounts of axons
19
Q
thoracic part of spinal cord: grey matter vs white matter
A
mostly white matter due to limited muscles at thorax
20
Q
lumbar part of spinal cord: grey matter vs white matter
A
mostly grey matter (large amounts of cell bodies)
21
Q
sacral part of spinal cord: grey matter vs white matter
A
mostly grey matter (large amounts of cell bodies)
22
Q
___ pairs of spinal nerves
A
31
23
Q
____ pairs of cervical nerves
A
8
24
Q
____ pairs of thoracic nerves
A
12
25
____ pairs of lumbar nerves
5
26
____ pairs of sacral nerves
5
27
7 cervical vertebrate but ___ cervical nerves
8
28
cervical vertebrae nerves come out on top of ____
vertebrae
29
fetal vs adult development of spinal cord
spinal nerves lines up with vertebrae but all the upper body grows, spinal cord moves up but nerves still come out at original levels so spinal cord ends at L1-L2 but nerves continue past that
30
spinal cord organization
medulla oblongata -> L1-L2 conus medullaris -> cauda equina -> filum terminale
31
in spinal cord, white matter is on ___
outer layer
32
grey matter has two horns: ___
posterior (dorsal/sensory) horn
anterior (ventral/motor) horn
33
dorsal & ventral horns lead to _____ roots
dorsal & ventral roots
34
dorsal & ventral roots join up to form _____
spinal nerve
35
dorsal root ganglion is ____
cell bodies of sensory neurons
36
below the C7 vertebrae, spinal nerves come out ____
below the vertebrae
37
ventral root doesn't contain ____
ganglion only the dorsal root
38
sensory and motor information between brain, spinal cord and peripheral nerves and organ systems happens how often?
all the time, around the clock
39
ascending pathways are ____
sensory
40
descending pathways are ____
motor
41
ascending and descending pathways are made of _
chain of neurons and associated nuclei/ganglia
42
synapses are ___
inter-neuronal connections
43
what varies between pathways?
number of neurons and synapses
44
number of somatic sensory pathways
3
45
Three types of major sensory pathways
1. Dorsal column/medial leminscal pathway
2.Spinothalamic (anterolateral) pathway
3. Spinocerebellar pathway
46
Dorsal column/medial leminscal pathway controls ____
-joint/limb position & motion sense (conscious proprioception) + light touch
47
Spinothalamic (anterolateral) pathway controls ____
pain, noxious temperature
48
Spinocerebellar pathway controls _____
unconscious proprioception
49
Right hemisphere controls _____ and the left half controls ____
-the left side of the body
-the right side of the body
50
Dorsal column conveys ____ & _____ from ______
-joint position (conscious proprioception) & discriminative touch (3D recognition of objects w/o vision) from
trunk & extremities
51
Dorsal column pathways involves how many order neurons?
3 (three)
52
Dorsal column pathways: 1st order neuron
-from skin/joint receptor
-enters the spinal cord and ascends the white matter as the dorsal columns
-synapses at medulla (same side)
53
Dorsal columns consists of______
the mechanosensory axons
54
Dorsal column pathways: 2nd order neuron
-from medulla
-crosses to opposite side
-ascends as the medial lemniscus
-synapses at thalamus
55
Dorsal column pathways: 3rd order neuron
-from thalamus
-goes to primary sensory cortex to thalamocortical projections
56
thalamus acts as the ___
bouncer directing what goes to the brain from sensory nerves
57
Dorsal column pathway general image
58
Lateral Spinothalamic Pathway involves how many order neurons?
3 (three)
59
Lateral Spinothalamic Pathway: 1st order neuron
-from skin receptors
-synapses at dorsal horn of spinal cord
60
Lateral Spinothalamic Pathway: 2nd order neuron
-from dorsal horn
-crosses over on opposite side of spinal cord
-synapses at thalamus as lateral spinothalamic tract
61
Lateral Spinothalamic Pathway: 3rd order neuron
-from thalamus to primary sensory cortex via thalamocortical tract
62
Unconscious Proprioception (def.)
body knows where each muscle and joint is at all times
63
Lateral Spinothalamic Pathway general image
64
Spinocerebellar Pathway carries ____
unconscious proprioception (joint position + vibration sense) from trunk and extremities to cerebellum
65
Spinocerebellar Pathway involves how many order neurons?
2 (two)
66
Spinocerebellar Pathway : 1st order neuron
-from receptors in joint capsules, tendons, & muscle spindles
-synapses at dorsal horn spinal grey matter
67
Spinocerebellar Pathway : 2nd order neuron
-from dorsal horn
-to cerebellum via dorsal spinocerebellar tracts
68
Spinocerebellar Pathway general image
69
CNS issues ___ commands that are distributed to body by ___
motor
PNS
70
somatic motor commands effect contraction of ____ muscle
skeletal
71
somatic motor pathways involve at least ___ motor neurons
2 (two)
72
motor neurons involved in somatic motor pathways
-upper motor neuron (UMN)
-lower motor neuron (LMN)
73
UMN has cell body in ___ and synapses onto ____
CNS processing centres
LMN
74
LMN has cell body in ___ and synapses onto ____
ventral horn of spinal cord/motor cranial nerve nucleus in brainstem
skeletal muscle
75
Modulation of Lower Motor Neuron by Upper Motor Neuron (excitatory synapse)
UMN--> excites LMN -> excites muscle (large signal at muscle)
76
Modulation of Lower Motor Neuron by Upper Motor Neuron (inhibitory synapse)
UMN--> inhibits LMN -> inhibits muscle (small signal at muscle)
77
Upper Motor Neuron Lesion
UMN --> inhibitory synapse prevented --> LMN --> spastic paralysis (muscles are tight and hard- spasm-always active)
78
Lower Motor Neuron Lesion
UMN --> excitatory or inhibitory synapse --> no response leads to flaccid paralysis (relaxed and therefore shrink,)
79
only axon of ___ extends to skeletal muscle
LMN
80
Conscious motor commands controlling skeletal muscle travel via the ___ pathways
corticospinal or corticonuclear (corticobulbar)
81
Corticospinal (Pyramidal) pathway
-UMN extend from the cerebral cortex (Cortico) to the spinal cord (Spinal) which houses the LMN
- LMN extend axons to regulate muscles of the limbs + trunk
82
Corticonuclear (Corticobulbar) pathway
UMN extend from the cerebral cortex (Cortico) to motor
cranial nerve nuclei (LMN) in the brainstem (Nuclear [Bulbar])
- LMN extend axons to regulate muscles of the head + neck
83
corticospinal + corticonuclear pathway general image
84
Corticospinal Pathway originates from
pyramidal neurons in the cortex from:
-Primary motor cortex and Premotor cortex
85
______ regulate distal limb muscles à important for precise, skilled, learned movements (such as playing piano)
Corticospinal Pathway
86
Corticospinal Pathways path
Primary Motor (& Sensory) Cortex -> Internal Capsule -->Crus Cerebri in Midbrain --> Pyramids in Medulla --> Decussation of the Pyramids (crosses over) -> Lateral Corticospinal Pathway
87
Upper Motor Neuron Injury in corticospinal pathway
-Middle Cerebral Artery Stroke
-Internal Capsule stroke
-Brainstem Lesion
-Spinal Cord Injury
88
lower Motor Neuron Injury in corticospinal pathway
Spinal Nerve Injury
89
Voluntary Movements (summary of previous slide)
* Central Motor Program
1.Identification and localization of targets in space->posterior parietal cortex
2. Formulation of a plan of action --> premotor cortex &
supplementary motor cortex
Execution of the movement à primary motor cortex
90
Extrapyramidal Pathways (def.) + example
Subsidiary descending pathways that help with movement
- (ie: contract your bicep muscles (pyramidal tract), you need to relax your opposing triceps muscles (extrapyramidal tract)
91
Basal Nuclei and Cerebellum Modulate and modify_______
activity in the corticospinal tract to ensure smooth, coordinated, purposeful movement
