Apex- Neuraxials Flashcards
What are the others?
A- Transverse process
B- Superior articular process
C- Lamina
D- Spinous Process
How many vertebrae in the spine?
_ cervical, _ thoracic, _ lumbar, _ fused-sacral, _ fsed-coccygeal
33
7 cervical, 12 thoracic, 5 lumbar, 5 fused sacral, 4 fused coccygeal
The spinal nerves exit the vertebral column through what?
the intervertebral foramina
What do the facet joints do?
what can injury to a facet joint do?
they guide and restrict movement of the vertebral column
it can compress the spinal nerve as it exits the respective intervertebral foramina, causing pain and muscle spasm along the associated ermatome
Purpose of the intervertebral discs?
what happens when they degenerage?
they act as a shock absorber
the size of the intervertebral foramina reduces and can cause nerve compresion
What is the space that contains the spinal cord, nerve roots and epidural space?
vertebral foramen
label
C1 vs C2 - which one is the atlas and which one is the axis
C1- atlas
C2 - axis
atlas spins on the axis
whats the zygapophyseal joint?
the facet joint
formed by the inferior articular process of the above vertebra and the superior articular process below
What is the name (2) of the horizontal line drawn across the superior aspects of the iliaccrests and what vertebra does it correlate with?
intercristal line (Tuffier’s line)
L4
space above = L3-L4, space below = L4-5
Infants up to 1 year, the intercristal ilne correlates with what interspace?
L5-S1
What vertebral level corresponds with the spine of scapula?
What about the inferior angle of the scapula?
T3
T7
What vertebral level corresponds with the posterior superior iliac spine
What about the superior aspect of the iliac crest?
S2
L4 (intercristial line)
What vetebral level corresponds with the vertebra prominens?
C7
What vertebrae corresponds with the rib margin 10cm from midline?
L1
In the adult, which anatomic structure correlates with the termination of the dural sac?
A. Sacral cornua
B. Superior iliac spines
C. Tuffier’s line
D. L1 vertebra
B. Superior iliac spines
Superior aspects of the iliac CREST vs
Posterior suprior iliac SPINE
veretebre correlation vs landmark associate
iliac CREST : L4-5 interspace (Tuffier’s line)
iliac SPINE: S2 (Dural sac ends)
What vertebra is is the conus medullaris associated with?
L1
What provides an entry point to the epidural space that’s useful in pediatrics?
what vertebra does it coincide with? What is it covered by?
What’s the landmark for caudal anesthesia?
Sacral hiatus = entry point into the epidural space
S5 ; covered by the sacrococcygeal ligament
Sacral Cornua = landmark
The Spinal cord ends in a taper as the what?
Infant vs Adult
Conus medullaris
Adult - L1-L2
Infant: L3
What is the cauda equina?
what nerve and nerve roots is it made up of?
A bundle of spinal nerves extending from the conus medullaris to the dural sac
L2-S5 nerve and nerve roots & the coccygeal nerve
Where does the subarachnoid space end?
Landmark for adult vs infant?
dural sac
adult - S2
Infant - S3
What are the 5 ligaments of the spinal cord from superficial to deep?
which ones do you pass through with the midline approach to a spinal?
which ones what about the paramedian approach?
- supraspinous
- interspinous
- ligamentum flavum
- posterior longitudinal
- anterior longitudinal
supraspinous, interspinous, ligamentum flavum
paramedian = just the ligamentum flavum
What contributes to the loss of resistance encountered during neuraxial anesthesia?
piercing the ligamentum flavum when the needle enters the epidural space
2 ways t odo a paramedian approach?
15 degrees off midline or
1cm lateral and 1cm interior to the interspace
Where does the epidural space end?
The sacrococcygeal ligament
What 3 things does the epidural space contain?
What 4 things does the subarachnoid space contain?
nerve roots, fat pads, blood vessels
Spinal cord, CSF, nerve roots & rootlets
Significance of fat pads in the epidural space?
they act as a sink for lipophilic drugs, reducing their bioavailability
What will happen if an epidural dose vs spinal dose is injected into the subdural space
epidural dose will cause a high spinal
spinal dose will cause a failed spinal
What are Batson’s plexus?
Epidural veins that drain venous blood from the spinal cord
What’s the thing that may or may not exist but people blame as a culprit for difficult epidural catheter insertion or unilateral epidural blocks?
plica mediana dorsalis
-a connective band of tissue b/t the ligamentum flavum and the dura matter that could create a barrier and would impact the spread of medications within the epidural space
What structures does the needle pass through after piercing the ligamentum flavum?
epidural space > dura mater > subdural space > arachnoid mater > subarachnoid space > pia mater > spinal cord > posterior longitudinal ligament> bone
when performing spinal anesthesia, when do you feel the “pop”
once you pass through the dura mater (fibrous sheild that protects the spinal cord)
Transection of the C6 posterior nerve root will cause:
A. Diaphragmatic paralysis
B. Impaired sympathetic outflow to the C6 distribution
C. Sensory block of the thumb
D. Motor deficit of the middle finger
Sensory block of the thumb
*posterior roots = sensory; anterior roots = motor & autonomic
Diaphragmaticp aralysis would be injury to C3-C5
The spinal cord has how many paired spinal nerves?
31
what is a dermatome
an area of skin thats innervated by a dorsal nerve root (sensory) from the spinal cord
Dermatomes for:
C6, C7, C8
C6 = thumb
C7 = 2nd and 3rd digits
C8 = 4th and 5th digits
Dermatome levels for:
Nipple line, xiphoid process, umbilicus
anterior knee
Nipple line = T4
Xiphoid process = T6
Umbilicius = T10
L4 = anterior knee
label
label
With spinal anesthesia, what is the primary site the local anesthetic works on?
the myelinated preganglionic fivers of the spinal nerve roots
spinal anesthesia- which fibers/nerves are blocked first, second, third between motor, autonomic and sensory
first- autonomic (sympathectomy)
second- sensory
third- motor
(this is why that one CRNA only asks if they can lift their legs, bc if motor is blocked, than you know sensory is blocked, esp if you have a sympathectomy
Spinal anesthesia- autonomic block is how many dermatomes higher than the sensory blockade, and how much higher than the motor blockade?
compared to epidural?
autonomic 2-6 higher than sensory block
sesnory block = 2 dermatomes higher than motor
sensory block is 2-4 dermatomes higher than the motor block and there is no autonimic differential blockade
T/F- there is no autonomic differential blockade with epidural anesthesia
True
Where must local anesthetics go before blocking the nerve roots when injected epidurally?
they have to diffuse through the dural cuff before they can block the nerve roots
Primary determinants of spreaad for spinal vs epidural anesthesia (4/2)
spinal = dose and baricity; pt position and injection site
epidural = volume and level of injuection
t/f: bevel orientation does NOT meaningfully affect spread of the local anesthetic in the spinal space
true
what is the most reliable determinant of intrathecal spread when using a hypo or isobaric solution compared to a hyperbaric solution
hypo or isobaric -> dose = most reliable determinant of spread
hyperbaric > baricity = most reliable determinant of spread
*spinal = dose and baricity (position and site of injection)
Order of sensations blocked from first to last
1st = temp (alch pad)
2nd = pain (pinprick)
3d = light touch or pressure
Ratings of the modified bromage scale to assess the degree of motor block
0 = no motor block
1 = cant raise leg but can move knees and feet
2 = cant raise leg or move knee but can move feet
3 = complete motor block (cant move legs, knees, or feet)
What is the MOST appropriate spinal dose of 3% 2-chloroprocaine to achieve for a T10 level?
A. 5mg
B. 20mg
C. 30mg
D. 50mg
C. 30mg
3% 2-cholorprocaine is useful for pts who require a spinal for a very short period of time. The range needed to achieve a T10 level is 30-40mg.
What is the primary DRUG-related determinant of block height for an epidural?
what about primary PROCEDURE-related determinant?
what about primary determinant of block density?
drug-related factor = LA volume
PROCEDURE-related factor = level of injection
primary determinant of block density = LA concentration
0.5-0.75% BPV (no dextrose)
Dose for T10 vs T4
onset
duration
T10 - 10-15mg (2-3cc 0.5%; 1.3-2cc 0.75%)
T4 - 15-20mg (3-4cc 0.5%; 2-2.6cc 0.75%)
onset 4-8 mins
duration 130-220 mins (2-3.5hrs)
How much volume of epidural LA per segment to be blocked
what if your inserting epidural at L4-5 and want a T4 height?
1-2cc
(12 segments: 12-24ccs)
What is the “top-up” dose for epidurals?
50-75% of initial dose