Lecture 4 - Spinal Cord Flashcards
(114 cards)
1
Q
Where does the spinal cord begin and end?
- At what disc space level does it end?
The spinal cord is a ___________ of the _________________ (at the_______________) and ends at the _______________ , located at the disc space between _____ and _____.
A
The spinal cord is a continuation of the medulla oblongata (at the foramen magnum) and ends at the conus medullaris, located at the disc space between L1 and L2.
2
Q
Medulla Oblongata
A
Most inferior part of the brain stem
3
Q
What is the conus medullaris?
A
The conus medullaris is the tapered, lower end of the spinal cord, typically located around the level of the L1-L2 vertebrae in adults. It marks the transition from the spinal cord to the cauda equina, which is a bundle of nerve roots that extend downward from the conus.
4
Q
Where is the cervical enlargement of the spinal cord located?
The cervical enlargement extends from ____ to _____.
A
The cervical enlargement extends from C4 to T1.
5
Q
Where is the lumbar enlargement of the spinal cord located?
A
The lumbar enlargement extends from T9 to T12.
6
Q
What arises from the conus medullaris and anchors the spinal cord to the coccyx?
A
Filum terminale
7
Q
What is the filum terminale,
- Where does it arise from?
- What is its function?
A
The filum terminale is a fibrous extension arising from the conus medullaris.
It anchors the spinal cord to the coccyx.
8
Q
What important function does the spinal cord contain?
The spinal cord contains the ______________.
A
The spinal cord contains the major reflex center.
9
Q
How is the spinal cord protected?
- What is the cord completely surrounded by?
- What also protects the spinal cord?
A
The spinal cord is completely surrounded by the
- vertebrae
What else protects the spinal cord:
- meninges,
- cerebrospinal fluid (CSF), and
- intervertebral discs.
10
Q
How many layers of meninges are there?
A
3
11
Q
What are the meninges?
A
The meninges are three layers of membranes that protect the brain and spinal cord.
12
Q
Spinal meninges are…
A
Continuous with the cranial meninges
13
Q
What are the three layers of the meninges?
- From the outermost layer to the innermost layer?
A
The three layers of the meninges are:
- Dura mater (outermost layer)
- Arachnoid mater (middle layer)
- Pia mater (innermost layer)
14
Q
Pia Mater
A
Innermost layer
15
Q
Arachnoid Mater
A
Middle layer
16
Q
Dura Mater
A
Outermost layer
17
Q
What is the function of cerebrospinal fluid (CSF) in spinal cord protection?
A
CSF acts as a shock absorber, cushioning the spinal cord from injury.
18
Q
What role do intervertebral discs play in spinal cord protection?
A
Intervertebral discs provide cushioning between vertebrae, absorbing shock and reducing stress on the spinal cord.
19
Q
How are the spinal meninges related to the cranial meninges?
A
The spinal meninges are continuous with the cranial meninges.
20
Q
How far do the spinal meninges extend?
A
The spinal meninges extend to the level of S2.
21
Q
What is the innermost layer of the meninges?
A
The pia mater is the innermost layer of the meninges.
22
Q
What is the middle layer of the meninges?
A
The arachnoid mater is the middle layer of the meninges.
23
Q
What is the outermost layer of the meninges?
A
The dura mater is the outermost layer of the meninges.
24
Q
Where is the epidural space located?
The epidural space is located between the __________ and the ___________.
A
The epidural space is located between the dura mater (outermost layer) and the vertebra.
25
What happens at the epidural space?
Epidural injection- local anaesthetic
26
What is the purpose of an epidural injection?
An epidural injection delivers local anesthetic into the epidural space to block pain.
27
Where is the subdural space located?
- The subdural space is between the __________ and the ________________.
The subdural space is between the dura mater and the arachnoid mater.
28
What does the subdural space contain
The subdural space contains interstitial fluid.
29
Where is the subarachnoid space located?
The subarachnoid space is between the arachnoid mater and the pia mater.
30
How far does the CSF go down to?
- At what vertebral level?
S2
31
What does the subarachnoid space contain, and what is its function?
The subarachnoid space contains cerebrospinal fluid (CSF), which acts as a shock absorber for the spinal cord.
32
If a patient requires a lumbar puncture (spinal tap), what position do we want them in and why?
- Pt on side, flex forward
- Need to open joint spaces
33
Lumbar puncture
- What vertebral level inthis performed at in an adult patient?
- In which space
- Why? What is the main reason we are going to that level in an adult?
- Level L3-L4
- Subarachnoid space
- Spinal cord ends at L1 and L2, should not be a risk of damaging the spinal cord.
## Footnote
A lumbar puncture (LP), or spinal tap, is performed in the subarachnoid space because this space contains cerebrospinal fluid (CSF), which is essential for diagnostic testing. The subarachnoid space, located between the arachnoid mater and pia mater,
Minimal Discomfort and Risk: In this area, the space between vertebrae is larger, and the spinal nerves are more spread out in the cauda equina (a bundle of nerve roots), making it a safer location for needle insertion with minimal risk of nerve damage.
Access to CSF: The subarachnoid space contains CSF, which can be collected to test for infections, bleeding, inflammation, or other neurological conditions like multiple sclerosis.
Safety: The subarachnoid space in the lower back (typically between the L3-L4 or L4-L5 vertebrae) is ideal for accessing CSF because the spinal cord itself ends at the level of the L1-L2 vertebrae, reducing the risk of injury to the cord.
34
Is a lumbar puncture/ spinal tap performed at the vertebral level L3?
NO
- L3 is solid bone, needle will not go through
- we need to go between the vertebrae to get to that subarchnoid space
- CANNOT SAY L3 FOR TESTING PURPOSES
35
The CSF extends down to S2, why don't we do a spinal tap at this level?
- No joint spaces
- Just solid bone
36
For lumbar puncture why not go in through L4-L5?
-There is more tissue down at this level
- Hard to get needle through
37
For lumbar puncture why not go in through L1-L2?
The spinal cord ends at this level and therefore there is a risk of causing nerve damage
38
For lumbar puncture why not go in through S2?
Solid bone
39
How many pairs of spinal nerves are there?
There are 31 pairs of spinal nerves.
40
Through which structures do spinal nerves exit the spine?
Spinal nerves exit the spine through the intervertebral foramina.
41
How many cervical spinal nerves are there?
There are 8 cervical spinal nerves.
42
How many thoracic spinal nerves are there?
There are 12 thoracic spinal nerves.
43
How many lumbar spinal nerves are there?
There are 5 lumbar spinal nerves.
44
How many sacral spinal nerves are there?
There are 5 sacral spinal nerves.
45
How many coccygeal spinal nerves are there?
There is 1 coccygeal spinal nerve.
46
How many pairs of spinal nerves are there?
31 pairs
47
Are all spinal cord segments aligned with their respective vertebrae?
No, not all spinal cord segments are aligned with their respective vertebrae.
48
Where does the spinal cord end?
The spinal cord ends at the L1/L2 level.
49
How do the **roots** of lumbar, sacral, and coccygeal nerves exit the spine?
They descend at an angle to exit through their respective intervertebral foramina.
50
What is the cauda equina?
| The cauda equina is a bundle of _________, __________, and ___________ n
The cauda equina is a bundle of lumbar, sacral, and coccygeal nerve roots that extend downward from the spinal cord to their exit points.
51
How are spinal nerves formed?
- What are they responsible for in the body?
Spinal nerves are formed by two roots from the spinal cord:
1. Posterior (Dorsal) Root – Sensory
2. Anterior (Ventral) Root – Motor
52
What is the function of the posterior (dorsal) root?
The posterior (dorsal) root carries sensory information to the spinal cord.
53
What is the function of the anterior (ventral) root?
The anterior (ventral) root carries motor information from the spinal cord to the body.
54
Are spinal nerves sensory, motor, or mixed?
All spinal nerves are mixed, meaning they contain both sensory and motor fibers.
55
Once the posterior (dorsal) root and the anterior (ventral) rooth pass out of the intervertebral foramina, what are they called?
Rami
56
What are the key components in the sensory pathway of the spinal nerves?
- Dorsal root
- Dorsal root ganglion
57
What type of neurons are found in the dorsal root?
The dorsal root contains only **axons** of sensory neurons.
58
What is the dorsal root ganglion?
****The dorsal root ganglion is a swelling on the dorsal root that contains the cell bodies of sensory neurons.
59
What are the two main components of the internal spinal cord anatomy?
The spinal cord consists of white matter and gray matter.
60
What structures are found in the white matter of the spinal cord?
The white matter contains:
- **Anterior** median **fissure** (deep groove in the front)
- **Posterior** median **sulcus** (shallow groove in the back)
61
What is the shape of the gray matter in the spinal cord?
The gray matter has an “H” or butterfly shape.
62
What are the main regions of gray matter in the spinal cord?
The gray matter consists of:
- Posterior (Dorsal) Horn
- Lateral Horn
- Anterior (Ventral) Horn
- Commissure
- Central canal
63
What is the commissure in the spinal cord?
The commissure is the crossbar of the “H” in the gray matter, connecting both sides of the spinal cord.
64
What is the central canal, and what does it contain?
The central canal extends the entire length of the spinal cord and is filled with cerebrospinal fluid (CSF).
65
What does the posterior (dorsal) horn of the spinal cord contain?
The posterior (dorsal) horn contains:
- Incoming sensory neurons
- Cell bodies and
- unmyelinated axons of interneurons
66
What does the anterior (ventral) horn of the spinal cord contain?
The anterior (ventral) horn contains somatic motor nuclei, which are clusters of cell bodies in the CNS.
67
What is the role of the anterior (ventral) horn?
The anterior (ventral) horn sends nerve impulses for the contraction of skeletal muscles.
68
What does the posterior (dorsal) horn of the spinal cord contain?
- Incoming sensory neurons
- Cell bodies of interneurons
Unmyelinated axons of interneurons
69
What is the function of the posterior (dorsal) horn?
The posterior (dorsal) horn processes incoming sensory information.
70
What does the anterior (ventral) horn of the spinal cord contain?
The anterior (ventral) horn contains somatic motor nuclei.
71
Somatic motor nuclei
72
What are nuclei in the CNS?
Nuclei are clusters of cell bodies in the central nervous system (CNS).
73
What is the function of the anterior (ventral) horn?
The anterior (ventral) horn sends nerve impulses that control the contraction of skeletal muscles.
74
Where is the lateral horn of the spinal cord found?
- Presentin?
The lateral horn is present only in the T and L segments of the spinal cord.
75
What does the lateral horn contain?
The lateral horn contains autonomic and enteric motor nuclei.
76
Autonomic and enteric motor nuclei
77
What are autonomic and enteric motor nuclei?
Autonomic and enteric motor nuclei are clusters of cell bodies of motor neurons that regulate:
The heart
Glands
Smooth muscle
78
What is white matter in the spinal cord made of?
White matter is made up of myelinated axons
79
Into what columns is white matter divided?
White matter is divided into three columns:
Posterior (Dorsal) Column
Lateral Column
Anterior (Ventral) Column
80
What do the columns of white matter contain?
The columns of white matter contain tracts.
81
What are tracts in the spinal cord?
Tracts are bundles of axons in the central nervous system (CNS).
82
Are sensory tracts in white matter ascending or descending?
Sensory tracts are ascending, carrying information toward the brain.
83
Are motor tracts in white matter ascending or descending?
Motor tracts are descending, carrying commands from the brain to muscles.
84
What does the posterior column of white matter contain?
The posterior column contains an ascending tract (sensory).
85
What do the lateral and anterior columns of white matter contain?
The lateral and anterior columns contain both:
Ascending tracts (sensory)
Descending tracts (motor)
86
What happens to spinal nerves after they pass through the intervertebral foramina?
After passing through the intervertebral foramina, spinal nerves branch into rami.
87
Do branches of spinal nerves (anterior rami) go directly to the area they supply?
No, branches of spinal nerves (anterior rami) do not go directly to the area they supply, except for the intercostal nerves (T2-T12).
88
What are the networks formed by the branches of spinal nerves called?
The branches of spinal nerves form networks called plexuses.
89
What are the five major types of nerve plexuses?
The five major nerve plexuses are:
Cervical plexus
Brachial plexus
Lumbar plexus
Sacral plexus
Coccygeal plexus
90
Which spinal nerves form the cervical plexus?
The cervical plexus is formed by the anterior rami of spinal nerves C1 to C5.
91
What areas of the body are supplied by the cervical plexus?
The cervical plexus supplies the head, neck, superior part of the chest, and shoulders.
92
What are the phrenic nerves, and where do they arise from?
The phrenic nerves arise from the cervical plexus at the levels C3, C4, and C5 and supply motor neurons to the diaphragm.
93
What muscles are innervated by the cervical plexus?
The cervical plexus innervates the following muscles:
Sternocleidomastoid
Erector spinae
Levator scapulae
94
How is pain from the diaphragm interpreted in the C3, C4, and C5 regions?
Sensory stimuli from the diaphragm are often interpreted as pain over the shoulder and lower neck due to referred pain.
95
Which spinal nerves form the brachial plexus?
The brachial plexus is formed by the anterior rami of C5-C8 and T1.
96
How is the brachial plexus divided?
he brachial plexus is divided into:
Roots
Trunks
Divisions
Cords
Nerves
97
What are the major nerves supplied by the brachial plexus?
The major nerves supplied by the brachial plexus are:
Musculocutaneous nerve
Axillary nerve
Radial nerve
Median nerve
Ulnar nerve
Long thoracic nerve
98
Which spinal nerves form the lumbar plexus?
The lumbar plexus is formed by the roots from L1 to L4.
99
What areas of the body are supplied by the lumbar plexus?
The lumbar plexus supplies the following areas:
Anterolateral abdominal wall
External genitals
Anterior part of the lower limbs
100
What are the major nerves supplied by the lumbar plexus?
The major nerves supplied by the lumbar plexus are:
Femoral nerve
Obturator nerve
Saphenous nerve
101
What areas of the body are supplied by the sacral plexus?
The sacral plexus supplies the following areas:
Buttocks
Perineum (genitals)
Posterior part of the lower limbs
102
What is the sciatic nerve, and what happens at the knee?
The sciatic nerve is a major nerve of the sacral plexus, and it branches into the tibial and common fibular nerves at the knee.
103
What is a dermatome?
A dermatome is an area of skin supplied by sensory neurons from a single spinal nerve.
104
Why are dermatomes useful?
Dermatomes are useful to determine neurologic levels.
105
Where is the integration center for some reflexes?
The spinal cord is the integration center for some reflexes.
106
What are examples of reflexes mediated by the spinal cord?
Examples of reflexes mediated by the spinal cord include:
Patellar reflex
Plantar reflex
107
What is the Babinski sign?
The Babinski sign is when the toes fan out and the great toe moves upward in response to a stimulus.
108
Is the Babinski sign normal for infants or adults?
The Babinski sign is normal for infants but abnormal for adults.
109
What is the function of the intervertebral foramina?
The intervertebral foramina are where the spinal nerves exit the spinal column.
110
What do you need to know about intervertebral foramina?
You need to know how to best demonstrate the intervertebral foramina for different spinal regions:
C-Spine
T-Spine
L-Spine
Sacrum
111
How can you best demonstrate the intervertebral foramina in the C-Spine?
To best demonstrate the intervertebral foramina in the C-Spine, use an oblique position with a 45-degree rotation and angled X-ray to capture the foramina clearly.
112
How can you best demonstrate the intervertebral foramina in the T-Spine?
To best demonstrate the intervertebral foramina in the T-Spine, use an oblique position with a 70-degree rotation and appropriate angulation of the X-ray beam.
113
How can you best demonstrate the intervertebral foramina in the L-Spine?
To best demonstrate the intervertebral foramina in the L-Spine, use an oblique position with a 45-degree rotation and ensure that the X-ray beam is parallel to the foramina.
114
How can you best demonstrate the intervertebral foramina in the sacrum?
To best demonstrate the intervertebral foramina in the sacrum, use an anterior oblique position with a slight rotation and careful X-ray angulation to visualize the foramina effectively.
