NEURO-Spinal cord Flashcards
(109 cards)
1
Q
describe the spinal cord circulation
A
Posterior spinal arteries (3)
Anterior spinal artery (1)
Radicular arteries (6 - 8)
2
Q
What portion of the spinal cord do each of the following perfuse
Posterior spinal aa.
Anterior spinal a.
Radicular aa.
A
Posterior spinal aa. = posterior 1/3 of SC
Anterior spinal a. = anterior 2/3 of SC
Radicular aa. = spinal aa. in thoracolumbar region of SC
3
Q
From which artery do the anterior and posterior spinal arteries arise
A
Vertebral arteries in the cervical region
Radicular and lumbar arteries below cervical level
4
Q
Where do the posterior spinal arteries run
A
The length of the spinal cord longitudinally on both sides of midline, in posteriorlateral sulcus
5
Q
Where does the anterior spinal artery fun
A
The length of the spinal cord, longitudinally along the anterior median fissure
6
Q
Name of the most important radicular artery
A
Artery of Adamkiewicz aka great radicular artery
7
Q
What is the importance of the artery of Adamkiewicz
A
It perfuses the anterior spinal cord in the thoracolumbar region
8
Q
Where does the artery of Adamkiewicz originate
A
Varies, person-to-person
Most commonly on LEFT side between T8 - T12
Rarely, L1 - 2
9
Q
Why is the anterior spinal cord susceptible to ischemia
A
Because it is highly dependent on radicular artery perfusion, and any interruption of radicular flow can cause ischemia to that portion of spinal cord
10
Q
How can spinal cord perfusion be affected by aortic x-clamping
A
Aortic x-clamp above the artery of Adamkiewicz can cause ischemia to the lower portion of the anterior spinal cord
11
Q
What are 4 s/sx of anterior spinal artery syndrome aka Beck’s syndrome
A
- Flaccid paralysis of LE
- Bowel and bladder dysfunction
- Loss of temperature and pain sensation
- Preserved touch and proprioception
12
Q
Which spinal pathways are perfused by the anterior blood supply
A
- Corticospinal tract
- Spinothalamic tract
- Autonomic motor fibers
13
Q
Why are touch and proprioception preserved in an individual with anterior spinal cord syndrome
A
Because the dorsal column is still being perfused via posterior spinal arteries
14
Q
How are autonomic motor fibers perfused in the spinal cord
A
Anterior spinal artery
15
Q
Define ganglion as it pertains to the spinal cord
A
A collection of cell bodies that reside outside of the CNS
16
Q
What is contained in the grey matter of the spinal cord
A
Neuronal cell bodies
17
Q
What is the function of grey matter in the spinal cord
A
Center for AFFERENT signals arriving from periphery
18
Q
Describe the subdivision of grey matter in the SC
A
There are 10 laminae
Laminae 1-6 are in the dorsal grey matter
Laminae 7-9 are in the ventral grey matter
Lamina 10 is around the central canal
19
Q
Which laminae are sensory and where are they located
A
Laminae 1 - 6
In the dorsal grey matter
20
Q
Which laminae are motor and where are they located
A
Laminae 7-9
In the ventral grey matter
21
Q
What is the difference between lamina 10 vs 1 - 9
A
10 is around the central canal
Anterior and posterior commissures comprise lamina 10
22
Q
Where is the Tract of Lissauer
A
It is immediately before lamina 1 in the dorsal grey matter
23
Q
How does the grey matter differ in the cervical and lumbar spine?
A
The grey matter is larger
C5-C7 = contains cell bodies for neurons supplying the UE
L3-S2 = contains cell bodies for neurons supplying LE
24
Q
What structures are contained in the white matter of the SC
A
The axons of the ascending and descending tracts
25
What are the divisions of white mater in the SC
Dorsal
Lateral
Ventral
26
Define tracts as it pertains to the SC
A group of fibers inside the white matter in the CNS
They relay information up or down the SC or to and from the brain
27
Which 4 spinal tracts are sensory
1. Cuneatus and gracilis in dorsal column
2. Tract of Lissauer
3. Lateral spinothalamic tract
4. Ventral spinothalamic tract
28
Which 2 spinal tracts are motor
1. Lateral corticospinal tract
| 2. Ventral corticospinal tract
29
Identify the corresponding tracts for each function
Fine touch and proprioception=
Pain and temperature=
Crude touch and pressure
Fine touch and proprioception= dorsal column: cuneatus and gracilis
Pain and temperature= tract of Lissauer and lateral spinothalamic tract
Crude touch and pressure= ventral spinothalamic tract
30
Identify the corresponding tract for each function
Limb motor=
Posture motor=
Limb motor= lateral corticospinal tract
| Posture motor= ventral corticospinal tract
31
```
Identify the corresponding function for each tract
Ventral spinothalamic tract=
Lateral spinothalamic tract=
Dorsal column cuneatus gracilis=
Tract of Lissauer=
```
Ventral spinothalamic tract= crude touch and pressure
Lateral spinothalamic tract= pain and temperature
Dorsal column cuneatus gracilis= fine touch and proprioception
Tract of Lissauer= pain and temperature
32
Identify the corresponding function for each tract
Ventral corticospinal tract =
Lateral corticospinal tract =
Ventral corticospinal tract = posture motor
| Lateral corticospinal tract = limb motor
33
What is the function of the dorsal column-medial lemniscal system
Transmits mechanoreceptive sensations:
- fine touch
- proprioception
- vibration
- pressure
Ability to determine two-point discrimination
34
What types of nerve fibers are contained in the dorsal column-medial lemniscal system
Large, myelinated, rapidly conducting fibers
35
How is the speed of conduction in the dorsal column compared to the anterolateral system
Dorsal column transmits sensory information faster than the anterolateral system
36
Where does the dorsal column-MLS synapse with the 2nd order neuron
Medulla (cuneate and gracile nuclei)
37
Where does the dorsal column-MLS cross-over to contralateral side of the SC
In the medulla
38
Where does the dorsal column third order neuron arise
The thalamus in the ventrobasal complex
39
What types of peripheral nerves make up the first-order neuron of the dorsal column-MLS
A-beta nerves
| Some A-alpha nerves
40
How do dorsal column-MLS first-order neurons enter the spinal cord
via the dorsal root ganglion
41
On which side of the SC does the dorsal column-MLS ascend
Ipsilateral side
42
What is the final destination of the third-order neuron of the dorsal column-MLS
Via the internal capsule to the somatosensory cortex in the postcentral gyrus in parietal lobe
43
What 5 sensations are transmitted via the anterolateral system via the spinothalamic tract
1. pain
2. temperature
3. itch
4. tickle
5. crude touch
6. sexual sensation
44
What type of neurons are contained the anterolateral spinothalamic tract
Smaller, myelinated AND nonmyelinated, slower conducting fibers
45
How does the speed of conduction for the anterolateral spinothalamic tract compare to the dorsal column-MLS
The anterolateral spinothalamic tract is 1/2 to 1/3 as fast as the dorsal column
46
What nerve fiber types are contained in the anterolateral spinothalamic tracts and their functions
A-delta = "fast" pain, mechanoreceptor
C-fibers = "slow" pain, polymodal receptors
47
Where is the cell body for the anterolateral-STT located
Dorsal root ganglion
48
How do anterolateral-STT first-order neurons ascend
They may ascend or descend 1-3 levels on the ipsilateral side in the Lissauer tract then synapse
49
Where do first-order neurons of the anterolateral-STT synapse with the second-order neuron
In the tract of Lissauer 1 - 3 levels above or below where they entered the SC
50
Which lamina contains the substantia gelatinosa
Rexed's lamina 2
51
Where do pain neurons of the anterolateral-STT synapse with 2nd-order neurons
In the substantia gelatinosa of Rexed's lamina 2
52
Where can primary pain neurons of the anterolateral-STT synapse with 2nd-order neurons
In the dorsal horn lamina 1, 4, 5, and 6
53
Where does the anterolateral-STT cross-ver
in the spinal cord as the 2nd-order neuron
54
Where do cell bodies for the second-order neurons of the anterolateral-STT reside
The dorsal horn of the SC
55
The 2nd-order neuron of the anterolateral-STT contains which 2 pathways
Anterior spinothalamic tract (crude touch, pressure)
| Lateral spinothalamic tract (pain and temp)
56
Where do 2nd-order neurons of the anterolateral-STT synapse with 3rd-order neurons
In the reticular activating system and thalamus
57
Where do pain fibers from the anterolateral-STT synapse with 3rd order neurons
In the reticular activating system
58
Where do tactile signals from the anterolateral-STT terminate
Via the internal capsule to somatosensory cortex in the postcentral gyrus of the parietal lobe
59
Nociceptive neurons primarily synapse with second-order neurons where
Substantia gelatinosa of dorsal horn (lamina 2)
| They may also synapse in laminae 1, 4, 5, or 6
60
Where do motor neuron signals originate
Precentral gyrus of frontal lobe
61
How do motor neuron signals travel to the spinal cord
they exit the precentral gyrus, pass through the internal capsule, then travel inferiorly through the pyramids of the medulla
62
Where does the lateral corticospinal tract crossover to the contralateral side
In the medulla
63
Where do nerve fibers in the ventral corticospinal tract crossover to the contralateral side
In the spinal cord either when they reach the cervical or upper thoracic area
64
Where do the upper motor neurons of the corticospinal tract synapse with lower motor neurons
In the ventral horn of the SC
65
Where are the cell bodies for the upper motor neuron located
In the cerebral cortex
66
How does upper motor neuron injury in the corticospinal tract present
Contralateral spastic paralysis + hyperreflexia
67
Why does spastic paralysis occur with injury to upper motor neurons
Normally, inhibitory neurons of CST influence lower motor neurons, preventing lower neurons from firing too frequently.
When upper motor neurons are injured, the inhibitory impulses from the brain are blocked at the level of the injury
68
What are 2 examples of upper motor neuron injury
Cerebral palsy
| Amyotrophic lateral sclerosis
69
What is the Babinksi test assessing
The integrity of the corticospinal tract
70
What does a positive or negative Babinksi test indicate
Negative = CST is intact. Toes curl downward
Positive = damage to CST. Toes flex outward
71
Where do lower motor neurons of the CST begin and end
```
Begin = In the ventral horn
End = NMJ
```
72
Where are the cell bodies of the lower motor neurons located
In the ventral horn
73
What is the function of the lower motor neuron
To send signal from spinal cord to muscles
74
How does injury to the lower motor neuron of the CST present
Ipsilateral flaccid paralysis
| Impaired reflexes
75
What is another name for the corticospinal tract
Pyramidal tract
76
What does a positive Babinski test indicate
Toes fan outward
| Indicates injury to corticospinal tract
77
Where does the upper motor neuron of the CST begin and end
```
Begins = precentral gyrus of frontal cortex
End = ventral horn of spinal cord
```
78
How does sympathectomy manifest below the level of a spinal cord injury
Bradycardia
Hypotension
Hypothermia
79
What spinal level are the cardioacceslerator fibers
T1-T4
80
What is the consequence of impaired cardioaccelerator fibers
1. Unopposed cardiac vagal tone
| 2. Bradycardia and reduced inotropy
81
What are 3 consequences of decreased SNS as a result of SCI
1. Vasodilation
2. Venous pooling
3. Decreased CO/BP
82
What are 2 consequences of impaired sympathetic pathways following SCI
1. Inability to vasoconstrict or shiver
| 2. Hypothermia
83
Why does hypothermia occur following SCI
It's a result of the inability of cutaneous vasculature to vasoconstrict causing redistribution of BF towards periphery allowing for more heat to escape the body
84
What are 2 differences between neurogenic vs hypovolemic shock
Neurogenic shock includes bradycardia and warm extremities along with hypotension
Hypovolemic shock includes tachycardia with cool, clammy extremities
85
Which vasopressor is a good choice during acute neurogenic shock following SCI
Levophed, to restore SVR and inotropy
86
What are the major causes of morbidity and mortality in patients with cervical and upper thoracic SCI
Ineffective alveolar ventilation and the inability to clear pulmonary secretions
87
When is succinylcholine safe to give to a patient with a severe SCI
Within the first 24 hrs, although this may worsen the SCI
88
What type of paralysis is associated with a severe C7 SCI 6 weeks after the acute phase
Spastic paralysis
89
After the spinal shock phase ends, the body has a return of what type of reflexes.
Above or below the injury
Spinal sympathetic reflexes below the level of injury
90
Why does autonomic hyperreflexia occur in high-level SCI
Spinal sympathetic reflexes have returned below the level of the injury
Without inhibitory influences that normally come from ABOVE the level of injury, the sympathetic reflexes below the level of injury exist in an overactive state
91
What are 6 common events that cause autonomic hyperreflexia
1. Stimulation of hollow organs (bowel, bladder, uterus)
2. Bladder cath
3. Surgery (esp cystoscopy or colonoscopy)
4. Bowel movement
5. Cutaneous stimulation
6. Childbirth
92
What are the common hemodynamic changes with autonomic hyperreflexia
HTN
| Bradycardia
93
What is the process of autonomic hyperreflexia when stimulation occurs below the level of SCI
1. sympathetic nerves are activated
2. Vasoconstriction below level of injury
3. HTN
4. Baroreceptor reflex at carotid sinus
5. Bradycardia
6. Inhibitory signals from brain for vasodilation don't transmit below level of SCI
94
What happens to vessels above the level of SCI during an incidence of autonomic hyperreflexia
Vasodilation from baroreceptor reflex stimulation (this does not transmit below the level of SCI
95
What s/sx may occur in conjunction with autonomic hyperreflexia
1. Nasal stuffiness
2. HA
3. Blurred vision
4. Stroke
5. SZ
6. LV failure
7. Dysrhythmias
8. Pulmonary edema
9. MI
96
Best anesthetic choices for patients with high-level SCI
GA
| Spinal anesthesia
97
What are 3 treatments for HTN in patients with autonomic hyperreflexia
1. Remove stimulus
2. Deepen anesthetic
3. Rapid-acting vasodilator (nitroprusside)
98
Which agents best treat bradycardia during autonomic hyperreflexia
Anticholinergics (atropine or glycopyrrolate)
99
Which medication can worsen HTN in patients with autonomic hyperreflexia and bradycardia
Giving a positive chronotrope with vasoconstrictive properties (ephedrine)
100
What is the result of amyotrophic lateral sclerosis
Progressive degeneration of motor neurons in the corticospinal tract
101
What type of cells replace affected motor neurons in ALS
Astrocytic gliosis
102
What upper motor neuron s/sx present with ALS
1. Spasticity
2. Hyperreflexia
3. Loss of coordination
103
What lower motor neuron s/sx present with ALS
1. Muscle weakness
2. Fasciculations
3. Atrophy
104
What symptoms of autonomic dysfunction present with ALS
1. Orthostatic HoTN
| 2. Resting tachycardia
105
What type of drug is the only medication that can reduce mortality in patients with ALS
Riluzole which is an NMDA receptor antagonist
106
What type of response to patients with ALS have to nondepolarizing NMBD
Increased sensitivity
107
What are 3 pulmonary anesthetic considerations in patients with ALS
1. Bulbar muscle dysfunction increases risk of aspiration
2. Chest weakness reduces VC and maximal Vm
3. Postop mechanical ventilation may be necessary
108
Which type of mechanoreceptor allows a patient with blindness to read braille
Meissner's corpuscles
109
The tract of Lissauer is a component of which spinal pathway
Spinothalamic tract
