lecture 6 - spinal cord: internal topography Flashcards
(97 cards)
1
Q
the spinal cord is omposed of two colored tissue areas, what are they?
A
gray matter, white matter
2
Q
which is the innermost color tissue area?
A
inner gray, outer white
3
Q
describe the gross anatomy of the gray matter
A
- anterior (ventral) horn
- posterior (dorsal) horn
- lateral horn
- each side of the gray matter is a mirror image
- each sides connected by the gray commissure
- ventral roots
- dorsal roots
4
Q
the anterior horn is made up of which type of neurons?
A
somatic motor neurons
5
Q
the posterior horn is made up of which type of neurons?
A
sensory neurons
6
Q
the lateral horn is made up of which type of neurons?
A
autonomic
7
Q
what (specifically) are the ventral roots?
A
motor axons to skeletal muscle (efferents)
8
Q
what (specifically) are the dorsal roots?
A
sensory impulses (afferents, dorsal root ganglion)
9
Q
what are the types of somatic motor neurons?
A
alpha and gamma
10
Q
what do alpha motor neurons innervate?
A
skeletal muscle
11
Q
what do gamma motor neurons innervate?
A
muscle spindles
12
Q
alpha motor neurons are aka?
A
lower motor neurons
13
Q
why are alpha motor neurons organized into groups (or, longitudinal columns)?
A
each column innervates a different muscle
14
Q
what are the alpha motor neuron columns separated by?
A
interneurons
15
Q
what are the alpha motor neuron columns?
A
medial, lateral and central
16
Q
what does the medial column of alpha motor neurons innervate?
A
axial muscles (neck, trunk and intercostal (btwn ribs))
17
Q
what does the lateral column of alpha motor neurons innervate?
A
limbs
18
Q
what is unique about the lateral column of alpha motor neurons?
A
anterior horn expands at this column because there are more skeletal muscles to innervate in the limbs
19
Q
what does the central column of alpha motor neurons innervate?
A
depends on the level of the spinal cord:
- C4-C5: phrenic nucleus (motor innervation to diaphragm)
- C6-C7: spinal accessory nucleus (contains axons from cranial nerve XI)
- L2-S1: lumbosacral nucleus (dont know what this one does)
20
Q
how many nerve cell groups does the posterior horn contain?
A
4 - substantia gelatinosa, nucleus proprius, dorsal nucleus, visceral afferent nucleus
21
Q
does the substantia gelatinosa span the entire length of the cord?
A
yes
22
Q
what type of neurons is the substantia gelantinosa composed of?
A
golgi type II neurons
23
Q
what are the functions of the substantia gelatinosa?
A
pain, temperature, touch
24
Q
does the nucleus proprius span the entire length of the cord?
A
yes
25
what are the functions of the nucleus proprius?
proprioception, two-point discrimination, vibration
26
which nucleus makes up the bulk of the posterior horn?
nucleus proprius
27
does the nucleus dorsalis span the entire length of the cord?
no: C8/T1 - L2/L3
28
what are the functions of the nucleus dorsalis?
proprioception (neuromuscular and tendon spindles)
29
what is the nucleus dorsalis aka?
Clarke's Column (or, nucleus)
30
what is unique about the nucleus dorsalis?
actually located more in the intermediate gray matter, but does sensory processing so its considered a part of the dorsal horn
31
does the visceral afferent nucleus span the entire length of the cord?
no: T1-L3
32
what are the functions of the visceral afferent nucleus?
visceral afferents, involved in initiation of sympathetic response
33
where are the 4 nuclei located relative to each other?
substantia gelatinosa most dorsal, then nucleus proprius, then dorsal nucleus, then (mostly laterally) the visceral afferent nucleus
34
describe the intermediate horn from T1-L3
preganglionic sympathetic neurons
35
dscribe the intermediate horn from S2-S4
preganglionic parasympathetic neurons
36
what is lamina I
marginal nucleus
37
what is lamina II
substantia gelatinosa
38
what is lamina III
nucleus proprius
39
what is lamina IV?
nucleus proprius
40
what is lamina V?
neck of dorsal horn (pain)
41
what is lamina VI?
base of dorsal horn (muscle tone)
42
what is lamina VII?
intermediate gray matter zone (incl. nucleus dorsalis)
43
what is lamina VIII?
interneuron zone
44
what is lamina IX?
motor cells of anterior horn
45
what is lamina X?
gray matter surrounding the central canal
46
what are the dorsal laminae?
I-VI
47
what are the lateral laminae?
VII, X
48
what are the anterior laminae?
VIII, IX
49
describe the white matter of the spinal cord
divided into anterior, lateral and posterior faniculi
50
are there ascending tracts in all 3 faniculi?
yes
51
are there descending tracts in all 3 faniculi?
no - only anterior and lateral
52
what surrounds the gray matter in all 3 faniculi?
intersegmental fiber tracts
53
describe the ascending tracts of the posterior faniculi
- funiculis gracilis (caudal - T6) (medial)
| - funiculis cuneatus (rostral - T6) (lateral)
54
what does the funiculis gracilis innervate?
legs
55
what does the funiculis cuneatus innervate?
arms
56
how are the ascending tract of the posterior funiculis organized?
somatotopically
57
what lemniscus system is the ascending tract of the posterior funiculis a part of? thus, what is its function?
- medial lemniscus system
| - fine touch, vibration, pressure, 2 point discrimination, proprioception
58
describe the ascending tracts of the lateral funiculi
- posterior lateral tract (Lissauer's tract)
- posterior spinocerebellar tract
- anteroir spinocerebellar tract
- lateral spinothalamic tract
- spinotectal tract
- spino-olivary tract
59
where is the posteriolateral tract (Lissauer's tract)?
between substantia gelatinosa and the surface of the cord
60
what is the function of the posteriolateral tract?
pain and temperature
61
where is the posterior spinocerebellar tract?
- originates from clarke's nucleus
- curved band at periphery of lateral white funiculi begining at posteriolateral tract
- projects ipsilateral to the cerebellum
62
what is the function of the posterior spinocerebellar tract?
tactile, pressure, proprioceptive information from the leg
63
where is the anterior spinocerebellar tract?
curved band at the periphery of lateral white funiculi extending from the posterior cerebellar tract to the anterior white funiculi
64
what is the function of the anterior spinocerebellar tract?
converys information from the leg to the cerebellum
65
how do the anterior and posterior spinocerebellar tracts differ?
anterior fibers cross the midline in the cord only to cross back in the pons (ipsilateral to their origin)
66
where is the lateral spinothalamic tract?
- axons cross the midline of the cord to form this tract
| - lies medial to the anterioe spinocerebellar tract
67
what is the function of the lateral spinothalamic tract?
pain and temperature
68
what is unique about the lateral spinothalamic tract?
its somatotopically organized
69
where is the spinotectal tract?
-medial to the anterior spinocerebellar tract, anterior to the lateral spinothalamic tract
70
what is the function of the spinotectal tract?
visual reflex information (movments of eyes/head towards the source of stimulation)
71
where is the spino-olivary tract?
at the junction of the anterior and lateral white funiculi
72
what is the function of the spino-olivary tract?
carries info from cutaneous and proprioceptive organs to the cerebellum
73
describe the ascending tracts of the anterior funiculi
anterior spinothalamic tract
74
where is the anterior spinothalamic tract?
axons cross the midline to form this tract medial to the ventral nerve roots
75
what is the function of the anterior spinothalamic tract?
carries information about light touch and pressure
76
what is unique about the anterior spinothalamic tract?
its somatotopically organized
77
describe the descending tracts of the lateral white funiculi
- lateral corticospinal tract
- rubrospinal tract
- olivospinal tract
78
where is the lateral corticospinal tract?
posterior half of the lateral funiculus, medial to the posterior spinocerebellar tract
79
what is the function of the lateral corticospinal tract?
motor pathway for voluntary movement
80
where does the lateral corticospinal tract originate?
from neurons in the cerebral cortex
81
where is the rubrispinal tract?
anterior to the lateral coritcospinal tract
82
what is the function of the rubrospinal tract?
influences alpha and gamma motor neurons
83
where does the rubrospinal tract originate?
from the red nucleus in the midbrain
84
where is the olivospinal tract?
lateral to the vental roots, only in the upper cervical segments
85
describe the descending tracts of the anterior funiculi
- anterior corticospinal tract
- vestibulospinal tract
- tectospinal tract
86
where is the anterior corticospinal tract?
along the anterior median fissure, only in the cervical and thoracic segments
87
what is the function of the anterior corticospinal tract?
control the neck and shoulder muscles
88
where is the vestibulospinal tract?
periphery of the anterior white funiculi
89
where does the vestibulospinal tract originate?
pons and medulla
90
what is the function of the corticospinal tract?
carries information from the inner ear and cerebellum to muecles for maintenance of balance
91
where is the tectospinal tract?
- lateral to the margin of the anterior median fissue
- originates from the superior colliculus of the midbrain, then crosses the midline and ends up in the upper cervical segments
92
where does the tectospinal tract (descending) originate?
from the superior colliculus
93
what is the function of the tectospinal tract (descending)?
refelex postural movements
94
do axons enter laterally or medially to pre-existing neurons?
lateral
95
where do ascending tracts go?
thalamus, brainstem, and cerebellum
96
where are descending tracts coming from?
cerebral cortex, brainstem and spinal cord
97
describe the blood supply of the spinal cord
- (2) vertebral arteries
- ( 1) anterior spinal artery
- (2) posterior spinal arteries
- may also come from PICA
- radicular ateries (branches of the thoracic and abdominal aorta)
