Neuraxial Anatomy Flashcards
1
Q
What is the total number of cervical vertebrae?
A
7
2
Q
What is the total number of Thoracic vertebrae?
A
12
3
Q
What is the total number of Lumbar vertebrae?
A
5
4
Q
What is the total number of Sacral vertebrae?
A
5
5
Q
What is the total number of Coccyx vertebrae?
A
4
6
Q
What is the location of the conus medullaris in an adult?
A
Conus medullaris terminates at L1/L2 in the adult
7
Q
What is the location of the conus medullaris in an newborn?
A
L3
8
Q
What is the spinal cord referred to after the conus medullaris?
A
cauda equina (L2 – sacral)
9
Q
What is a lumbar laminectomy?
A
Surgery that creates space by removing the lamina
10
Q
What is the goal of lumbar laminectomy?
A
Enlarges your spinal canal to relieve pressure on the spinal cord or nerves
11
Q
What is important to know about the vertebral column?
A
Size and shape of vertebral lamina and spinous processes differ
12
Q
What is the characteristics of the cervical and thoracic vertebrae?
A
have more acutely angled spinous processes
13
Q
What is the characteristics of the lumbar vertebrae?
A
larger and spinous processes are shorter, broader, and have less overlap
14
Q
Where is it more difficult to access the areas for spinal and epidural placement?
A
Cervical and thoracic
15
Q
Where is it more easier to access the areas for spinal and epidural placement?
A
Lumbar
16
Q
There are ______ natural curves in the vertebral column.
A
four
17
Q
What are the concave anteriorly vertebrae?
A
thoracic and sacral
18
Q
What are the concave posteriorly vertebrae?
A
cervical and lumbar
19
Q
Define scoliosis.
A
Lateral curvature, Most common abnormal curvature
20
Q
Define Kyphosis.
A
Excessive posterior curvature or hump, typically in thoracic region
21
Q
Define excessive lordosis.
A
Hollowing of the back as body attempts to restore center of gravity
22
Q
What is the spinothalamic function of the spinal cord?
A
pain, temperature, itch, and general or light touch sensations
23
Q
What is the corticospinal function of the spinal cord?
A
voluntary motor function
24
Q
What is the major vessel that supplies blood to the thoracolumbar segment?
A
Artery of Adamkiewicz
25
What is another name for Artery of Adamkiewicz?
Also known as a radicular artery or radiculo-medullary artery
26
What is important to know about the origination of the artery of Adamkiewicz?
Nagelhout T7
Barash T8-T12 in 75% of cases and L1/L2 in an additional 10% of cases
27
Where does the Artery of Adamkiewicz supply blood?
Provides major blood supply to the lumbar and sacral cord.
28
What can happen if loss of flow occurs with the Artery of Adamkiewicz?
Loss of flow can result in anterior spinal artery syndrome (watershed area)
29
What is decreased in anterior spinal artery syndrome (watershed area)?
Dysfunction of the anterior 2/3 of the cord, including the anterior horns, the spinothalamic tracts, and the corticospinal tracts
30
How do patients present with anterior spinal artery syndrome (watershed area)?
acute paraparesis and impaired bowel and bladder function
31
What are the characteristics of the supraspinous ligaments?
Strong and cordlike
32
What does the supraspinous ligament connect?
Connects the apices of the spinous processes
33
What is the major ligament in the cervical and upper thoracic region?
Supraspinous ligaments
34
What are the three layers of the supraspinous ligaments?
Superficial layer, Middle and Inner layer
35
What is the characteristics of the interspinous ligament?
- Absent or in poor quality in the cervical region
- Thin in the lumbar region
36
What are the three posterior spinal ligaments?
Interspinous ligament & Supraspinous ligaments, Ligamentum Flavum
37
What is the characteristics of the ligamentum flavum?
- Strongest posterior ligament
- Joins the vertebral arches through vertical extensions for the adjacent lamina
38
Where does the ligamentum flavum run?
Runs caudad from the inferior border of one lamina to the upper border of the lower lamina on both sides of the midline
39
Where does the ligamentum flavum get thicker?
At the L2–L3 interspace, the ligamentum flavum is 3- to 5-mm thick. (NYSORA)
40
Define ligamentum flavum
Ligamentum flavum: “yellow ligament” made of elastin that preserves upright posture- the elastin prevents buckling of the ligamentum into the spinal canal during extension
41
What is the entire length of the spinal cord?
42-45cm in length
42
Where does the spinal cord terminate in adults?
Terminates at L2 in most adults, Approximately a 1% exception to this rule
43
Where does the spinal cord terminate in children?
Caused by the vertebral column growing faster than the spinal cord
44
Where does the spinal cord taper?
conus medullaris
45
What is the cauda equina?
Nerve pathways continue in a collection of rootlets called the cauda equina or horse’s tail
46
What is cauda equine syndrome?
Occurs when the nerve roots of the cauda equina are compressed and disrupt motor and sensory function to the lower extremities and bladder
47
Where is the cervical enlargement of the spinal cord located?
C4-T1
Brachial plexus
48
Where is the Lumbosacral enlargement of the spinal cord located?
L2-S3
Lumbar and Sacral Plexuses
49
What are the two spinal enlargements of the spinal cord?
Cervical Enlargement & Lumbosacral Enlargement
50
What are the three layers of the spinal cord?
Dura mater, arachnoid and pia mater
51
What are the meninges?
Provide a protective covering for the cord and nerve roots
52
Where do the meninges extend?
Extend from the foramen magnum to the base of the cauda equine
53
What is the location and function of the dura mater?
- Outermost layer
- Covers the nerve roots while they are inside the spinal canal
54
What is the most protective layer of the spinal cord?
Dura mater
55
What is considered the subarachnoid space?
The space under this meninge is considered the subarachnoid space and is filled with CSF
56
What is the characteristics of the pia mater?
- Thin
- In direct contact with the spinal cord
57
What is the characteristics of the arachnoid mater?
- Very thin
- Consistency of a spiders web
58
What is the epidural space?
A potential space outside the dural sac but inside the vertebral canal
59
Where does the epidural space occur?
Continuous from the base of the cranium to the base of the sacrum at the sacrococcygeal membrane
60
What is contained in the epidural space?
Contains epidural veins, fat, lymphatics, segmental arteries and nerve roots
61
What is fat in terms of the epidural space?
Fat is physiologically fluid acting as padding and lubrication for the movement of neural structures within the canal
62
What is important to know about the distance to the epidural space in individuals?
Distance to epidural space varies with vertebral level and is loosely correlated with patient weight
63
What offers greatest epidural space?
Midline approach (versus paramedian) offers greatest epidural space
64
What is the distance from the skin to the lumbar epidural space?
2.5-8cm, mean 5cm
65
What is the distance from the midline thoracic epidural space?
3-5 cm
66
What is the distance from the midline lower cervical region of epidural space?
1.5-2cm
67
What is a dermatome?
The area of cutaneous sensation supplied by a spinal nerve that is anatomically identified as it passes through an intervertebral foramen
68
What can be useful to help identify dermatomes?
Anatomic map
69
Dermatomes are based on what?
cutaneous sensation
70
What is the function of dermatomes in anesthesia?
Used to document the functional level of blockade in regional anesthetics
71
What is the primary site of MOA of local anesthetics?
on the nerve roots within the spinal cord
72
What is affected with drug concentrations at a minimal effective concentration?
When drug concentrations reach a minimum effective concentration neuronal transmission is altered by affecting sodium ion channels
73
Neurons differ in _______ to local anesthetics
Susceptibility
74
What is a differential block?
finds lack of transmission of autonomic nerves, but retains sensory and motor nerve function
75
When can differential blocks be used?
Differential blocks an opportunity/risk in cases where sensory anesthesia is the goal without sympathetic blockade in patients with coexisting disease
76
Label the dermatome man.
Slide 27
77
What are the components of differential blockade?
Sensory, motor, sympathetic nerve functions obtunded at different rates and degree
78
What gives a differential block its main characteristics?
size, myelination, ion channel composition, LA type and concentration
79
What is the onset sequence of neuraxial blockade?
Autonomic→ superficial pain→ touch→ temperature→ motor function→ proprioception (Nagelhout & Elisha)
80
What is the reverse sequence of neuraxial blockade?
proprioception→function→ motor →temperature → touch→pain→ superficial →Autonomic
81
What is true about sympathetic blockade and differential?
Differential blockade of the local anesthetics (sympathetic blockade may be a high as 2-6 dermatomes higher than the sensory); which is higher than the motor block
82
What is true about analegisa differential blockade?
(loss to sharp pain) 2+ segments cephalad than touch- sometimes patient still feel “touch” or pulling sensations on less dense blocks- shouldn’t be painful
83
What is the sensation block order?
cold temp; sharp pain; touch
84
What is true about the MOA of an epidural injection?
must spread and diffuse through meninges and dural cuffs to reach nerve roots or spinal cord
85
Neuraxial: Injectate travels by ________ flow rather than diffusion and in a non-circumferential manner
bulk
86
What is true about the MOA of spinal injections?
denser unless modifications are made to the epidural, such as increasing concentration, volume, or time
87
What are the abolute and relative contraindications to neuraxial?
Review slide 34
88
What is the contraindicated platelet count for a neuraxial?
Platelets less than 100,000 and/or PT/PTT/Bleeding time greater than 2x normal
89
Can you do a neuraxial on a tattoo?
Depends on when and where it was done
90
What is occuring in this picture? What is the intervention?
Epidural hemotoma, immediately going to the OR
