organisation of spinal cord Flashcards
(72 cards)
1
Q
what makes up the cns?
A
brain and spinal cord
2
Q
what does the spinal cord connect?
A
the brainstem and spinal nerves
3
Q
what protects the spinal cord?
A
the bony vertebral canal
4
Q
what makes up the brainstem?
A
midbrain, pons and medulla
5
Q
what part of the brainstem is continuous with the spinal cord?
A
medulla
6
Q
what foramen does the spinal cord leave through the brain?
A
magnum
7
Q
what are the meninges?
A
3 protective layers around the CNS to protect it
8
Q
what are the layers of the meninges?
A
dura mater
arachnoid mater
pia mater
9
Q
what is the extra/epidural space?
A
fat-filled space between dura mater and vertebrae only found in the spinal cord
10
Q
what is the subdural space?
A
potential space between arachnoid mater and dura mater
11
Q
what is the subarachnoid space?
A
actual space between arachnoid mater and pia mater
12
Q
in which space is the CSF found in the spinal cord?
A
subarachnoid layer
13
Q
what is the function of the CSF?
A
fluid which surrounds the CNS and buffers and protects it
14
Q
what is a lumbar puncture?
A
when a sample of CSF is taken by a needle being inserted into the subarachnoid space
15
Q
what is an epidural?
A
Insert anaesthesia into epidural space which will then diffuse across spinal nerves.
16
Q
describe the structure of a motor neuron
A
- Dendrites sticking out from the cell body
- Cell body is at one end
- Axon covered in a myelin sheath
17
Q
describe the structure of a sensory neuron?
A
- Dendrites at one end picking up sensory information from environment
- Cell body in the middle of the neuron sticking out from the axon
18
Q
what makes up white matter?
A
axons covered in myelin
19
Q
name the white matter funiculi?
A
posterior
lateral
anterior
20
Q
what makes up grey matter?
A
no myelinated components (cell bodies and synapses)
21
Q
name the grey matter horns
A
posterior
anterior
lateral - only in thoracic region
22
Q
why is the lateral horn of grey matter found in the thoracic region?
A
thoracic region is where the cell bodies for sympathetic nerves originate
23
Q
in the spine, is grey or white matter on the inside?
A
grey
24
Q
in the brain, is grey or white matter on the inside?
A
white
25
what part of the spinal cord do sensory nerves enter?
posterior/dorsal part of the spinal cord
26
where are sensory neuron cell bodies found?
outside the spinal cord
27
where are motor neuron cell bodies found?
inside the spinal cord
28
where does information in the white matter go?
up or down the spinal cord
29
how are cervical spinal nerves named?
according to the vertebrae below?
30
how many pairs of spinal nerves are there? state how many nerves are in each region
```
31 pairs of spinal nerves
o 8 cervical
o 12 thoracic
o 5 lumbar
o 5 sacral
o 1 coccygeal
```
31
which is shorter; the spinal cord or the vertebral column?
spinal cord
32
at what vertebral level does the spinal cord end in an adult?
L1/2
33
at what point in the spinal cord are there swellings?
cervical region
| lumbosacral region
34
why is there a swelling in the cervical region of the spinal cord?
its the point where the nerve innervating the brachial plexus and the upper limb leave the spinal cord
35
why is there a swelling in the lumbo-sacral region of the spinal cord?
where the nerves innervating the lower limb leave the spinal cord
36
what is the conus medularis?
tapering of the end of the spinal cord
37
what is the cauda equina?
below L1/2 where the spinal nerves are bunched together
38
when is the cauda equina formed?
during development
39
which grows faster; the vertebral column or the spinal cord?
vertebral column
40
at what spinal level are lumbar punctures and epidurals performed?
L3 to avoid spinal cord damage
41
describe the proportion of grey and white matter in the cervical region of the spinal cord?
large amounts of white matter and large ventral and dorsal horns
bc of large amounts of sensory and motor innervation to upper limb
42
describe the proportion of grey and white matter in the thoracic region of the spinal cord?
large proportions of white matter
| lateral horns of grey present
43
describe the proportion of grey and white matter in the lumbar region of the spinal cord?
little white matter
| large ventral and dorsal horn bc a lot of sensory and motor innervation
44
describe the proportion of grey and white matter in the sacral region of the spinal cord?
- Narrow bc most tracts haven’t entered yet or they’ve left
- Very little white matter
- Predominantly grey matter
45
what do vertebral arteries branch off?
subclavian artery
46
what foramens do the vertebral arteries run through?
transverse foramena
| foramen magnum
47
what do the 2 vertebral arteries anastomose to form?
basilar artery
48
how is an anterior spinal artery formed?
a branch from each vertebral artery anastomoses
49
what arteries supply blood to the spinal cord?
anterior and posterior spinal arteries reinforced by radiculospinal arteries from body wall arteries which come in and anastomose with the anterior spinal artery at every vertebral level
50
which part of the spinal cord is supplied by the anterior spinal arteries?
the majority
51
which part of the spinal cord is supplied by the posterior spinal arteries?
the posterior funiculi
52
describe the venous drainage system of the spinal cord
Venous drainage is via 3 anterior and 2-3 posterior spinal veins
53
what is the function of the spinothalamic tract?
transmitting the sensations of crude touch (pressure), pain and temperature from the spinal cord to the thalamus
54
define decussation
when a neuron travels from one side of the nervous system to the other
55
explain the pathway of information through the spinothalamic tract
first order neuron transmits sensation from skin along spinal nerve and into dorsal root
synapses with SON in dorsal horn of grey
goes from grey to white matter
decussates immediately after FON and SON synapse
SON travels via spinothalamic tract to the thalamus then synapses with TON
TON travels via internal capsule to primary somatosensory cortex in the brain
56
how many neurons are involved in the spinothalamic tract?
3
57
what is the function of the dorsal column medial lemniscus?
Transmits sensations of vibrations, proprioception (position in space) and discriminative touch (textures of things) from periphery to the brain via the dorsal columns and medial lemniscus
58
describe the pathway of information through the dorsal column medial lemniscus
FON transmits sensation from skin along spinal nerve to dorsal root
FON doesnt synapse - runs into dorsal column towards brainstem
FON ascends along dorsal column to enter medulla - synapses with SON within cunate/gracile nucleus
decussates to reach medial lemniscus
SON travels to thalamus via the medial lemniscus
SON synapses with TON
TON to primary somatosensory cortex
59
what are the dorsal columns and where do they run?
fasiculus gracilis from lower limb
| fasciculus cuneatus from upper limb)
60
what is the function of the spinocerebellar tract?
Transmitting the sensations of subconscious proprioception (position in space) from the spinal cord to the cerebellum
61
why is there no decussation in the spinocerebellar tract?
Cerebellum doesn’t work on a contralateral basis – left side works with the left side of the body
62
explain the pathway of the spinocerebellar tract?
- FON transmits sensation along spinal nerve and travels via dorsal root into spinal cord
- In the spinal cord, FON synapses in dorsal horn of grey
- SON enters ipsilateral spinocerebellar tract and ascends to the cerebellum
63
what is the function of the corticospinal tract?
transmitting the motor signals from the cortex to the spinal cord
64
describe the pathway of information in the corticospinal tract
FON has cell body in primary motor cortex
axon projects along the internal capsule to brainstem
FON runs anteriorly in brainstem and enters medullary pyramids
majority of fibres decussate to enter corticospinal tract
FON descends to level of innervation and enters ventral horn of grey and synapses with SON
travels out of spinal cord into spinal nerve to skeletal muscle
65
name the main ascending tracts
Dorsal column medial lemniscus
-Fasciculus gracilis – found medially. Takes info from lower limb
Fasciculus cuneatus – found laterally. Takes info from upper limb
Spinocerebellar
Spinothalamic
66
name the main descending tracts
corticospinal
67
how does a complete spinal cord injury occur and what does it result in?
spinal cord is fully compressed or severed. Results in complete loss of sensory and motor information below level of lesion
68
how does an incomplete spinal cord injury occur?
spinal cord is compressed or injured but the brain’s ability to send signals below site of injury isn’t completely removed
69
name examples of incomplete spinal cord injury
central cord
brown-sequard
stroke to the anterior spinal artery
70
how do patients with a central cord injury present?
upper limb weakness and sensory loss below the level of injury. Upper extremities are classically more affected than the lower extremities with motor function more severely impaired than sensory function
71
which part of the spinal cord is most affected in a central cord injury?
medial corticospinal tract is affected
innermost part
72
how does brown-sequard present?
paralysis and loss of proprioception/vibration/discriminative touch on the ipsilateral side as the injury
Loss of pain and temperature on the opposite (or contralateral) side as the lesion
