M6 SPINAL CORD Flashcards
1
Q
Connects the brain with most of the body
A
Spinal cord
2
Q
Occupies the upper 2/3 of the adult spinal canal within the vertebral column
A
Spinal cord
3
Q
Normally 42 to 45 cm long
A
Spinal cord
4
Q
Is the conical distal (inferior) end of the spinal cord
A
Conus medullaris
5
Q
In adults, the conus ends at what level of the vertebral column?
A
L1 OR L2
6
Q
What nuerons do the lateral enlargements at the cervical and lumbosacral levels accomodate?
A
Upper and lower limb innervation
7
Q
It is inferior to the end of the spinal cord.
A
Filum terminale
8
Q
It is a bundle of connective tissue and glia that connects the end of the cord to the coccyx.
A
Filum terminale
9
Q
Filum terminale is a bundle of ______________ and ____ that connects the end of the cord to coccyx?
A
Connective tissue and glia
10
Q
Long roots are required for axons from the termination of the cord to exit the lumbosacral vertebral column.
A
Cauda equina
11
Q
Is lined with ependymal cells and filled with csf.
A
Central canal
12
Q
Central canal is lined with what? And filled with what?
A
Ependymal cells and CSF
13
Q
Opens upward into the inferior portion of the fourth ventricle
A
Central Canal
14
Q
Spinal Cord Segments (adults)
A
C8, T1, T12, L5, S
15
Q
Vertebral Bodies of C8
A
C6-7
16
Q
Vertebral Bodies of T1
A
C7-T1
17
Q
Vertebral Bodies of T12
A
T10-T11
18
Q
Vertebral Bodies of L5
A
T12-L1
19
Q
Vertebral Bodies of S
A
L1-2
20
Q
Bony spinous processes (adults)
A
C6, T3, T8, T10, and T12,L1
21
Q
Anatomy of spinal cord, superior to inferior.
A
Conus medullaris, cauda equina, and filum terminale
22
Q
Cross section of the spinal cord
A
Deep median fissure and shallow posterior median sulcus
23
Q
Divides the cord into symmetric right and left halves joined in the central midportion
A
Deep median fissure
24
Q
Contains a fold of pia and blood vessels
A
Anterior median fissure
25
Floor of anterior median fissure
Anterior white commissure
26
Attached to the spinal cord along a shallow vertical groove
Dorsal nerve roots
27
Lies at a short distance anterior to the posterior median sulcus
Posterolateral sulcus
28
Where do ventral nerve roots exit?
Anterolateral sulcus
29
True or false:
Each segment of the spinal cord gives rise to four roots.
True
30
How many pairs of spinal nerves has a ventral root and a dorsal root?
31 pairs
31
Each root is made up of how many rootlets?
1 to 8 rootlets
32
Axons sending information to the periphery leave the anterolateral cord in small groups
Rootlets
33
Dorsal root of a typical spinal nerve, close to the junction with the ventral root
Dorsal root ganglion
34
A swelling that contains nerve cell bodies that give rise to sensory axons
Dorsal root ganglion
35
Portion of a spinal nerve outside the vertebral column
Peripheral nerve
36
Surrounds and protects the spinal cord
Vertebral column
37
Vertebraes
7 cervical
12 thoracic
5 lumbar
1 sacrum
1 coccyx
38
Exit of nerve roots from the vertebral column
Intervertebral foramina
39
Form from the ventral rootlets from a single segment coalesce
Ventral roots
40
Contains sensory axons that bring information into the spinal cord and enter the posterolateral spinal cord via rootlets
Dorsal root
41
Has a dorsal root ganglion located outside the spinal cord
Dorsal root
42
Contains the cell bodies of sensory neurons
Dorsal root ganglion
43
Sensory axons enter the spinal cord, the large-diameter fibers, transmitting proprioceptive and touch information, are located medially: small-diameter fibers, transmitting pain and temparature information are located laterally
Dorsal root ganglion
44
Sensory axons that transmit proprioceptive and touch information that are located medially.
Large diameter fibers
45
Sensory axons that transmit pain and temperature information that are located laterally.
Small diamete fibers
46
What roots join briefly to form a spinal nerve?
Dorsal and ventral
47
Smaller gamma motor neuron axons supply?
Intrafusal muscle of the muscle spindles
48
Preganglionic autonomic fibers:
Thoracic, upper lumbar, and midsacral levels
49
Largely sensory
Dorsal root
50
Contains afferent fibers from the nerve cells in its ganglion
Dorsal nerve root
51
*contains fibers from cutaneous and deep structures
Dorsal root
52
Largest fibers come from muscle spindles and participate in spinal cord reflexes
Dorsal root
53
Impulses from mechanoreceptors in skin and joints
Dorsal root
54
Nerve roots are small and carry
Dorsal root
55
Branches of typical spinal nerves
Posterior primary division, anterior primary division, and Rami communicantes
56
Medial branch, largely sensory and lateral brach, mainly motor
Posterior primary division
57
Larger than the posterior primary division
Anterior primary division
58
Forms the cervical, brachial, and lumbosacral plexus
Anterior primary division
59
Thoracic region, it remains segmental as intercostal nerves
Anterior primary division
60
Join the spinal nerves to the sympathetic trunk
Rami communicantes
61
Only the thoracic and upper lumber nerves with white ramus communicans, but the gray ramus is present in all spinal nerves
Rami communicantes
62
Made up of two symmetric portions joined across the midline
Gray matter: Columns
63
Cross section of the spinal cord shows an H shaped internal mass of gray matter surrounded by white matter
Columns
64
Extends the entire length of the spinal cord and is considered to consist of columns
Gray matter
65
Column in front of the central canal
Ventral gray column
66
It contains the cells of origin of the fibers of the ventral roots, incl. Alpha and gamma motor neurons
Ventral gray column
67
Lies between the dorsal and ventral gray columns
Intermediolateral gray column
68
Columns is also called?
Horn
69
Prominent lateral triangular projection in the thoracic and upper lumber regions but not in the midsacral joint
Intermediolateral gray column
70
Give rise to sympathetic axons that leave the spinal cord within the ventral roots
Lateral horn
71
Gives rise to preganglionic parasympathetic axons that leave the spinal cord within the sacral ventral roots
Sacral parasympathetic neurons
72
Reaches almost to the posterolateral sulcus
Dorsal gray column
73
A compact bundle of small fibers; part of the brain pathway, lies on the periphery of the spinal cord
Dorsolateral fasciculus
74
A cross section of the gray matter of the spinal cord shows a number of laminas
Rexed's laminae
75
Classified into 10 histologic regions of spinal gray matter
Rexed's laminae
76
General principle, superficial laminae tend to be involved in pain signaling while deeper laminae are involved in non painful as well as painful sensation
Rexed's laminae
77
How many laminas do the spinal cord have?
10 laminas
78
The thin marginal layer contains neurons
Lamina I
79
Respond to noxious stimuli and send axons to the contralateral spinothalamic tract
Lamina I
80
Made up of small neurons, some of which respond to noxious stimuli
Lamina 2 Substansia Gelatinosa
81
A neuropeptide involved in pathways mediating sensibility to pain, is found in high concentrations in laminas 1 and 2
Substance P
82
Main input is from fibers that convey position and light touch sense
Laminas 3 and 4 nucleus propius
83
Contains cells that respond to both noxious and visceral afferent stimuli
Lamina 5
84
Deepest layer of dorsal horn contains neurons that respond to mechanical signals from joint and skin
Lamina 6
85
Represent motor neuron groups in the medial and lateral portions of the ventral gray column
Laminas 8 and 9
86
Contains the LMNs that innervate axial musculature
Medial motor neuron column
87
Contains the LMNs for the distal muscles of the arm and leg
Lateral motor neuron column
88
Represents the small neurons around the central canal or its remnants
Lamina 10
89
White columns are called?
Funiculi
90
Divided into a medial portion and a lateral portion
Cervical and upper thoracic regions
91
Lies between the posterolateral sulcus and the anterolateral sulcus
Lateral column
92
Lies between the anterolateral sulcus and the anterior median fissure
Ventral column
93
Arising from the cerebral cortex
Corticospinal tract
94
A large bundle of myelinated axons that descend through the brain stems via a tract called the medullary pyramid and then largely crosses over downward into the lateral white columns.
Corticospinal tract
95
Contains axons of upper motor neurons
Corticospinal tract
96
Anterior horn cells, which project directly to muscle and control muscular contraction
Lower motor neurons
97
2 major components of the vestibulospinal tract
Lateral and medial vestibulospinal tract
98
Fibers arise from the lateral vestibular nucleus in the brainstem and course downward, uncrossed, in the ventral white column
Lateral vestibulospinal tract
99
Fibers arise in the medial vestibular nucleus in the brainstem and descend within the cervical spinal cord, with both crossed and uncrossed components, to terminate at cervical levels
Medial vestibulospinal tract
100
Provides synaptic inputs to interneurons in rexed's laminae 7 and 8 which project to both alpha and gamma LMNs.
Fibers of both vestibulospinal tracts
101
Facilitates quick movements in reaction to sudden changes in body position and provides control of antigravity muscles
Vestibulospinal system
102
Fiber system arises in the contralateral red nucleus in the brain stem and courses in the lateral white column
Rubrospinal tract
103
Projects to interneurons in the spinal gray columns and plays a role in motor function
Rubrospinal tract
104
Arises in the contralateral red nucleus in the brain stem and courses in the lateral white column
Fiber system
105
Arises in the reticular formation of the brain stem and descends in both the ventral and lateral white columns
Reticulospinal system
106
Both crossed and uncrossed descending fibers are present
Reticulospinal system
107
The fibers terminating on dorsal gray column neurons may modify the transmission of sensation from the body, especially pain.
Reticulospinal system
108
Arising from the hypothalamus and brainstem
Descending autonomic system
109
Projects to preganglionic sympathetic neurons in the thoracolumbar spinal cord and to preganglionic parasympathetic neurons in sacral segment
Descending autonomic system
110
Modulate autonomic functions, such as blood pressure, pulse and respiratory rates and sweating
Descending autonomic system
111
Tract arises from the superior colliculus in the roof of the midbrain then courses in the contralateral ventral white column to provide synaptic input to ventral gray interneurons
Tectospinal tract
112
Head turning in response to sudden visual or auditory stimuli
Tectospinal tract
113
Convey localized sensations of fine touch, vibration, two point discrimination, and proprioception from the skin and joint.
Dorsal column tracts
114
Carries input from the lower half of the body, with fibers that arise from the lowest, most medial segments.
Fasciculus gracilis
115
Lies between the fasciculus gracilis and the dorsal gray column
Fasciculus cuneatus
116
It carries input from the upper half of the body, with fibers from the lower segments more medial than the higher ones
Fasciculus cuneatus
117
Small diameter sensory axons convey the sensations of sharp pain, temperature, and crudely localized touch course upward.
Spinothalamic tracts
118
Ascending stretches of incoming fibers that synapse with dorsal column neurons, especially in laminas 1, 2, and 5
Dorsolateral fasciculus
119
Subsequent fibers cross to the opposite side of the spinal cord and then ascend within the spinothalamic tracts
Ventrolateral system
120
Carries information about light touch
Anterior spinothalamic tract
121
Pain and temperature sensibility upward
Lateral spinothalamic tract
122
ill defined spinoreticular tract courses within the ventrolateral portion of the spinal cord, arising from cord neurons and ending in the reticular formation of the brainstem
Spinoreticular pathway
123
Plays an important role in the sensation of pain, especially deep, chronic pain
Spinoreticular pathway
124
Two ascending pathways provide input from the spinal cord to the cerebellum
Spinocerebellar tracts
125
2 pathways of spinocerebellar tracts
Dorsal and ventral spinocerebellar tracts
126
Forms the dorsal spinocerebellar tract
Second order neurons from dorsal nucleus of Clarke
127
Forms the cuneocerebellar tract
Lateral cuneate nucleus
128
Involved with movement control
Ventral spinocerebellar tract
129
Second order neurons, located in rexed's laminae 5, 6, and 7 in lumbar and sacral segments of the spinal cord, send axons that ascend through the superior cerebellar peduncle to the paleocerebellar cortex
Ventral spinocerebellar tract
130
The axons of the second order neurons are largely but not entirely crossed
Ventral spinocerebellar tract
131
Involves the afferent neuron and its axon within a peripheral nerve and dorsal root and a motor unit at the same level
Segmental spinal reflexes
132
Involve specific patterns of muscle contractions, tha delay between stimulation and effect is caused by the time needed for propagation of the impulse along the nerve fibers concerned and the synaptic delay. 1 ms at each synapse
Simple reflex reactions
133
True or false:
A reflex arc must be intact for a particular reflex to be present.
True
134
Can provide information that is highly useful in the localization of lesions.
Evaluation of spinal reflexes
135
Stretch reflexes are also called?
Tendon or deep tendon reflexes
136
Provide a feedback mechanism for maintaining appropriate muscle tone
Stretch reflexes
137
Depends on specialized sensory receptors, afferent nerve fibers extending from these receptors via the dorsal roots to the spinal cord, two types of LMNs that project back muscle, and specialized inhibitory interneurons.
Stretch reflexes
138
Specialized mechanoreceptors are located within muscles and provide information about the length and rate of changes in the length of the muscle.
Muscle spindles
139
Muscle spindles surrounded by a connective tissue capsule
Intrafusal muscle fibers
140
Regular contractile units that provide the force underlying muscle contraction
Extrafusal muscle fibers
141
2 types of intrafusal fibers
Nuclear bag fibers and nuclear chain fibers
142
Run longitudinally within the muscle and are arranged in parallel with the extrafusal muscle fibers
Septae
143
2 types of afferent axons
Ia and II fibers
144
Arise from primary endings and secondary ending on the intrafusal fibers
Afferent axons
145
Carry impulses from the muscle spindle to the spinal cord via dorsal roots
Afferent axons
146
Responsible for muscle contraction that is innervated by large anterior horn neurons
Extrafusal muscle fibers
147
Propagate via axons in the ventral roots and peripheral nerves to the motor end plate where they have an excitatory effect and produce muscle contraction
Fire action potentials
148
Have diameters of 12 to 20 micrometer
Axons of alpha motor neurons
149
Interneurons, located in the ventral horn, project to alpha motor neurons and are inhibitory
Renshaw cells
150
Receive excitatory synaptic input via collaterals, whish branch from alpha motor neurons
Renshaw cells
151
Part of local feedback circuits that prevent overactivity in alpha motor neurons
Renshaw cells
152
Present with muscle tendons; stretch receptors are arranged in series with extrafusal muscle fibers and are activated by either stretching or contracting the muscle.
Golgi tendon organs
153
Group Ib afferent fibers run from the tendon organs via dorsal roots to the spinal gray matter
Golgi tendon organs
154
End on interneurons that inhibit the alpha motor neuron innervating the agonist muscle, thus mediating the inverse stratch reflexes
Golgi tendon organs
155
This feedback arrangement prevents the overactivity of alpha motor neurons
Golgi tendon organs
156
In LMN, the motor cell concerned with striated skeletal muscle activity consists of a ________ and ______ , which passes to the motor end plates of the muscle by way of the ________ nerves.
Cell body and axon, cranial
157
Considered the final common pathway because many neural impulses funnel through them to the muscle.
Lower motor neurons
158
Acted on by the corticospinal, rubrospinal, olivospinal, vestibulospinal, reticulospinal, and tectospinal tracts as well as by intersegmental reflex neurons
lower motor neurons
159
May be located in the cells of the ventral gray column of the spinal cord or brainstem or in their axons, which constitute the ventral roots of the spinal or cranial nerve.
Lesions of the LMNs
160
Damage to the cerebral hemispheres or lateral white column of the spinal cord can produce signs of?
Upper motor neuron lesions
161
Commonly seen as a result of strokes which can damage?
Upper motor neurons in the cortex
162
Signs when these neurons are damaged:
- Spastic paralysis or paresis
- no muscle atrophy
- hyperactive tendon reflexes
- babinski's sign
Upper motor neuron
163
Signs when these neurons are damaged:
- flaccid paralysis
- muscle atrophy
- fasciculations
Lower motor neurons
164
Can affect the decussating fibers of the spinothalamic tract from both sides without affecting other ascending or descending tracts
Small central lesion
165
Involves in addition to the pain and temp pathways, portions of adjacent tracts, adjacent gray matter, or both.
Large central lesion
166
Affects the dorsal columns, leaving other parts of the spinal cord intact
Dorsal column lesion
167
Proprioceptive and vibratory sensations are involved, but othe functions are normal
Dorsal column lesion
168
Examples are stab wound and compression of the cord
Irregular peripheral lesion
169
- Involves long pathways and gray matter.
- functions below the level of the lesion are abolished
Irregular peripheral lesion
170
Produces a brown séquard syndrome
Complete hemisection
171
- Such as neurofibroma or schwannoma
- Involves the first order sensory neurons of a segment an can produce pain as well as sensory loss
- deep tendon reflexes at the appropriate level may be lose because of damage to Ia fibers
Tumor of the dorsal root
172
- compresses the spinal cord against a vertebra causing dysfunction of ascending and descending fiber systems
Tumor of the meninges
173
Can metasize to the epidural space causing spinal cord compression
Tumors
174
Can also compress the spinal cord
Herniated intervertebral disks
175
May be treatable if diagnosed early
Spinal cord compression
176
Presents a classical clinical picture, characterized by loss of pain and temperature sensation at several segmental levels
Syringomyelia
177
Retains touch and pressure sense as well as vibration and position sense. Lesion usually involves the central part of the spinal cord and is confined to a limited no. of segments.
Syringomyelia
178
There is a capelike pattern of sensory loss
Cervical region lesion
179
LMN lesions and atrophy of the denervated muscles
Ventral gray matter
180
Form the tertiary neurosyphilis was common in the pre antibiotic era and is characterized by damage to the dorsal roots and dorsal columns
Tabes dorsalis
181
Impairment of proprioception and vibratory sensation, together with loss of deep tendon reflexes, which cannot be elicited because th Ia afferent pathway has been damaged
Tabes dorsalis
