Unit IV: Spinal Cord Flashcards
(137 cards)
1
Q
How long is the spinal cord?
A
16-18 inches
2
Q
At what vertebral level does the spinal cord occupy 75% of the vertebral canal?
A
C5-C6
3
Q
What is the superior boundary of the SC for convenience?
A
Foramen magnum
4
Q
What is the superior boundary of the SC being precise?
A
1st cervical spinal nerve
5
Q
What is the inferior boundary of the SC?
A
L1-L2: conus medullaris
6
Q
*How many pairs of spinal nerves are there?
A
31
7
Q
*What does the Bell-Magendi Law state?
A
Dorsal roots contain sensory (afferent) fibers and ventral roots are motor (efferent) fibers
8
Q
*Where are cervical spinal nerves found in position to its corresponding vertebra?
A
One above
9
Q
*Where are thoracic spinal nerves found in position to its corresponding vertebra?
A
One below
10
Q
*Where are lumbar spinal nerves found in position to its corresponding vertebra?
A
One below
11
Q
*S5 exits at the ___
A
Sacral hiatus
12
Q
*___ exits at the sacral hiatus
A
Co1-> may be missing
13
Q
*During the first 3 months of the embryonic development, the cord and the vertebral column are approximately the ___
A
Same length
14
Q
At birth, the Co1 cord level is at the same level as ___
A
L1-L3
15
Q
By adulthood, the Co1 cord level is found at ___
A
L1-L2
16
Q
The end of the SC is called the ___
A
Conus medullaris
17
Q
Through the lumbar cistern, the formation of the SC is called the ___
A
Cauda equina
18
Q
The ___ is continuous with the MO and 4th ventricle
A
Central canal
19
Q
The central canal expands in the conus medullar is as a ___
A
Terminal ventricle
20
Q
*Terminal vs. lumbar cistern
A
- both contain CSF
- T- within the cord
- L- outside the cord
21
Q
The dorsal horn of gray matter functions in ___
A
Sensory
22
Q
The lateral horns of gray matter functions in ___
A
Autonomic-> preganglionic
23
Q
The ventral horn of gray matter functions in ___
A
Motor
24
Q
What is a funiculus?
A
A longitudinal bundle of white matter fibers-> columns
25
White matter composition
1. dense concentrations of neuron cell bodies
2. many synaptic areas
3. support glial cells
4. dense capillary beds
26
*Rexed lamina I
Forms a thin cap over the dorsal horn
27
*RL II
1. "substantia gelatinosa"
| 2. important pain reception center
28
*RL III and IV
1. "nucleus proprius"
| 2. sensory receptors
29
*RL V
1. cervical area only
2. reticular formation
3. axons cross to the other side of the cord
30
*Which tract is found in RL V?
Lateral spinothalamic
31
*RL VI
1. missing at some cord levels
| 2. most anterior aspect of dorsal horn
32
*RL VII
1. intermediate gray area
2. descending fibers
3. C8-L3
4. lateral horn-> T1-L2
5. "sacral parasympathetic nucleus"
33
*Which tract is found in RL VII?
Posterior spinocerebellar tract
34
*RL VIII
1. anterior horn
2. delta motor neurons
3. most medial
35
*RL IX
1. skeletal muscles
2. "somatic motor horn"
3. class A alpha motor neurons
4. series of disconnected islands
36
*RL X
1. surrounds the central canal
2. gray commissures
3. crosses midline
37
* Blood vessels are ___ dense in white matter than in gray matter
Less
38
Fibers associate and stay together by surface proteins are called ___
NCAMs
39
*Are tracts observable by general staining techniques?
No
40
Sensory input enters the SC as ___ at the dorsal later sulcus
Dorsal root ganglion axons
41
Most axon will synapse in the ___ when entering the cord
Dorsal gray horn laminae
42
*Where is gracilis located?
Dorsal funiculus-> medial aspect
43
*Where is gracilis present?
In all cord levels
44
*Where do fibers synapse in gracilis?
MO
45
* Functions of gracilis
1. 2 point touch discrimination
2. vibratory sensations
3. kinesthetic sensation
46
*Pathway of gracilis
1. DRG at all cord levels-> MO
2. medial lemniscus-> thalamus
3. post. central gyrus
47
*Where is cuneatus located?
Dorsal funiculus-> lateral aspect
48
*Where is cuneatus present?
T6 and up
49
*Where do fibers synapse in cuneatus?
MO
50
*Functions of cuneatus
1. 2 point touch discrimination
2. vibratory sensations
3. kinesthetic sensation
51
*Pathway of cuneatus
1. DRG: T6 and up-> MO
2. medial lemniscus-> thalamus
3. post. central gyrus
52
*Where is the lateral spinothalamic tract located?
Lateral funiculus
53
*Where is the lateral spinothalamic tract present?
All cord levels
54
*What is the function of the lateral spinothalamic tract?
Pain/temperature
55
*Do fibers cross quickly or gradually in the lateral spinothalamic tract?
Quickly
56
*Pathway of the lateral spinothalamic tract
1. DRG-> cord level
2. (crosses quickly)-> VPL of the thalamus
3. post. central gyrus
57
*Where is the anterior spinothalamic tract located?
Anterior funiculus
58
*Where is the anterior spinothalamic tract found?
All cord levels
59
*What is the function of the anterior spinothalamic tract?
Light touch/pressure
60
*Do fibers cross quickly or gradually in the anterior spinothalamic tract?
Gradually
61
*Pathway of the anterior spinothalamic tract
1. DRG-> cord level
2. (crosses gradually)-> VPL of the thalamus
3. post. central gyrus
62
Lesions in the spinothalamic tracts lead to ___ and ___ on the opposite side of the body
Analgesia and thermoanaesthesia
63
What is analgesia?
Loss of pain sensation
64
What is thermoanaesthesia?
Loss of temperature sensation
65
*In the spinothalamic tracts, fibers terminate in the ___
VPL of the thalamus
66
*Where is the anterior spinocerebellar tract located?
Lateral funiculus
67
*Do fibers cross in the anterior spinocerebellar tract?
Yes, and cross back again in cerebellum
68
*Where are the fiber origins in the anterior spinocerebellar tract?
Lumbosacral cord's gray laminae
69
*Where do fibers terminate in the anterior spinocerebellar tract?
Cerebellum-> superior cerebellar peduncle
70
*What is the function of the anterior spinocerebellar tract?
1. gross movements of lower body
| 2. general activity of what is about to happen
71
*Where is the posterior spinocerebellar tract located?
Lateral funiculus
72
*Do fibers in the posterior spinocerebellar tract cross?
No
73
*Where are the fiber origins of the posterior spinocerebellar tract?
Nucleus dorsalis-> C8-L3
74
*Where do fibers terminate in the posterior spinocerebellar tract?
Cerebellum-> inferior cerebellar peduncle
75
*What is the function of the posterior spinocerebellar tract?
1. proprioceptive input dealing with mainly fine movements
| 2. what has just happened
76
*Pathway of the anterior spinocerebellar tract
1. DRG-> cord level
| 2. (crosses quickly)-> superior cerebellar peduncle-> crosses back-> opposite side of cerebellum
77
*Pathway of the posterior spinocerebellar tract
1. DRG (C8-L3)-> cord level-> inferior cerebellar peduncle-> cerebellum
78
*Proprioceptive fibers dealing with fine movements from the lower extremity may enter the cord ___
Below the nucleus dorsalis
79
*If proprioceptive fibers come from below the nucleus dorsals, which tract takes over and carries them to the designated spinal tract?
Gracilis
80
*Function of the cuneocerebellar tract
Fine movement proprioceptive fibers from the lower extremity
81
*Pathway of the cuneocerebellar tract
1. DRG (upper extremity)-> inferior cerebellar peduncle
| 2. cerebellum
82
6 ascending tracts
1. gracilis
2. cuneatus
3. lateral spinothalamic
4. anterior spinothalamic
5. anterior spinocerebellar
6. posterior spinocerebellar
83
*Where is the anterior corticospinal tract located?
Anterior funiculus
84
*How many fibers does the anterior corticospinal tract carry?
5-15%
85
*Where do fibers cross in the anterior corticospinal tract?
In the cord
86
*Where does the anterior corticospinal tract terminate?
By mid thoracic cord level
87
*What is the function of the corticospinal tract
Trick question- function is unclear
88
*Where is the lateral corticospinal tract located?
Lateral funiculus
89
*How many fibers does the lateral corticospinal tract carry?
85-95%
90
*Where do fibers in the lateral corticospinal tract cross?
Pyramids of the MO
91
*What level is the lateral corticospinal tract found at?
All cord levels
92
*What is the function of the lateral corticospinal tract?
Initiating and accomplishing precise skilled voluntary movements
93
*Pathway of the anterior corticospinal tract
1. motor cortex-> (crosses in cord)-> level of synapse
| 2. DRG
94
*Pathway of the lateral corticospinal tract
1. motor cortex-> (crosses in MO)-> level of synapse
| 2. DRG
95
*Tract that has the only axons that begin in the cerebral cortex and run uninterrupted to the spinal cord
Corticospinals
96
*Where do corticospinal tracts synapse?
Laminas VII and IX
97
*Most axons from the corticospinals are ___ from the pre central gyrus of the frontal lobe
Giant pyramidal (Betz) cells
98
What are lower motor neurons?
Originate in the spinal cord or brain stem and extend into the PNS
99
What are upper motor neurons?
Neurons that come from the cortex or brainstem that influence LMNs
100
Example of a UMN lesion
Cerebral Palsy
101
Example of a LMN lesion
Polio
102
*What are pyramidal neurons?
UMNs involved with the initiation of skilled voluntary movements
103
Example of a tract in the cord that is pyramidal?
Corticospinals
104
*What are extrapyramidal neurons?
1. UMNs which originate in the brain stem and extend down to the cord
2. influence posture, muscle tone, reflexes, smooth and effective voluntary movments
105
Examples of tracts that are extrapyramidal
1. tectospinal
2. rubrospinal
3. vestibulospinal
106
*Origin of the tectospinal tract
Superior colliculus of midbrain's tectum
107
*Do fibers cross in the tectospinal tract?
Yes- as they descend
108
*Where do fibers terminate in the tectospinal tract?
Upper 4 cervical cord levels
109
*What is the function of the tectospinal tract
Sight and auditory stimuli-> trapezius and SCM
110
*Pathway of the tectospinal tract
1. tectum-> (cross in MO)-> synapse before C4
111
*Origin of the rubrospinal tract
Red nucleus
112
*Do fibers cross in the rubrospinal tract?
Yes- in the midbrain
113
*Where is the rubrospinal tract found?
All cord levels
114
*What is the function of the rubrospinal tract?
Muscle tone control in the hand and foot
115
*Pathway of the rubrospinal tract
1. red nucleus-> (crosses in MO)-> level of synapse
116
*Origin of the vestibulospinal tract
MO-> Deiters' nucleus
117
*Do fibers cross in the vestibulospinal tract?
No
118
*Where is the vestibulospinal tract found?
All cord levels
119
*Function of the vestibulospinal tract
1. muscle tone and postural adjustment in extensor musculature
2. falling
120
*Pathway of the vestibulospinal tract
1. Deiters' nucleus-> level of synapse
121
*What is the function of the reticulospinal tract
Heart, blood pressure, and respiratory rates and rhythms
122
*Where is the fasciculus proprius found at?
Spinospinal fibers
123
*Function of the fasciculus propruis
Spinal reflexes
124
What fibers are the first to be myelinated in the fetus?
Fasciculus proprius
125
*Where is the dorsolateral located?
Between RL I and posterior lateral sulcus of the cord
126
Symptoms of UMN lesions
1. skeletal muscle becomes rigid
| 2. spasticity
127
Symptoms of LMN lesions
1. skeletal muscle wastes away
| 2. flaccidity
128
What vertebral levels are most common sites for severe injury?
C5/C6 and T12/L1
129
What is Brown-Sequard Syndrome?
Total loss of either the right or left side of the spinal cord
130
What is Tabes Dorsals?
Bacteria that wastes away the dorsal funiculus-> fasciculus gracilis
131
*What is multiple sclerosis?
Destruction of the CNS myelin-> interfascicular oligodendrocytes
132
*What is amyotrophic lateral sclerosis?
Destruction of UMNs and LMNs-> lateral corticospinal tracts
133
Toxins and myelin features
1. myelin alteration
| 2. hexachlorophene
134
What is pernicious anemia
1. deficiency of vitamin B12 due to intrinsic factor problems
2. CNS and PNS changes
135
What is syringomeylia?
The cord's central canal or adjacent areas begin to hollow out
136
What is poliomyelitis?
1. a virus altering of the sytoplasm of the neuron's cell body until cell death
2. scar tissue follows
3. upper cervicals-> respiratory failure
4. retrograde
137
Neoplasm and compression features
1. most common cord tumor-> ependymoma in the conus medullaris
2. most common vertebral canal tumor-> meningioma
3. glioblastoma multiforma
