Spinal Anesthesia Flashcards
How many vertebrae are there? How many in each section?
33 total
7 Cervical
12 thoracic
5 lumbar
5 sacral
4 coccygeal
how many facet joints between each vertebrae? and What kind of joints are they?
2, synovial joints
Another name for C1?
Atlas
another name for C2?
axis
motion of atlanto-axial joint?
side to side movement
Are facet joints a synovial filled cavity?
yes
where do spinal nerves exit?
from intervertebral foramen and sacral foramen
Adult spinal cord runs from what to what?
foramen magnum to L1-L2
where does spinal cord end in child?
L3
how many spinal nerves?
31 pairs
do bulbous portions of the spinal cord have more gray or white matter?
gray matter
where is cervical enlargment?
C1-C4
where is lumbar enlargement?
L2-S3
what is cervical enlargement responsible for?
anterior motor, upper limb muscles
what is lumbar enlargement responsible for?
lower limb muscles
Pia mater
thin delicate vascular membrane that covers the spinal cord.
how far lateral does pia mater go?
as far as intervertebral foramen
does the pia mater have projections that connect it to the arachnoid mater and dura mater?
yes
is arachnoid mater vascular?
no
where does subarachnoid space/arachoid mater end?
filum terminale
what structure does the duramater become continuous with?
epinerium as it passes through intervertebral foramen
when do you feel a pop with the spinal needle?
when it passes through the dura mater
where is the subdural space?
potential space between duramater and arachnoid mater
what can happen with injection into subdural space?
delayed block for 10-25min
also risk of VERY DANGEROUS high block
what neurons are located in anterior gray horn of spinal cord?
motor neurons
which tracts are located in the lateral gray horn?
corticospinal tracts
T1-L2 sympathetic motor neurons
S2-S4 parasympathetic pre and post ganglionic splenic, descending colon
cranial parasympathetic fibers deerived from fivers of the vagus nerve
where do cranial parasympathetic fibers enter the abdomen?
jointly with the esophagus and lie outside the subarachnoid space.
what do cranial parasympathetic fibers supply?
viscera
are cranial parasympathetic fibers affected very much by SAB/epidurals?
no, little affected
what can happen during surgery when retractors are on the mesentary? And how do you prevent this?
pt can have N/V, bradycardia, hypotension, and pain from the cranial parasympathetic fibers.
surgeon can block vagus nerve as it enters the abdomen. Or you can add GETA
what is contained in the posterior gray column?
substania gelationosa
nucleus proprius
nucleus dorsalis
visceral afferent nucleus
Tell me about the substania gelatinosa
afferents from dorsal roots syanpse here. Contain pain, temp, and crude touch via spinothalamic track
opioid receptors are here in dorsal horn
what do neuraxial opioids do?
inhibit release of excitatory neurotransmitters like substance P and glutamate and inhibit afferent neural transmission to the brain from peripheral nerves
tell me about the nucleus proprius
ascending pathway for general sensation, pain, temp, and tactile sensation
tell me about the nucleus dosralis
only in cervical and lower lumbar
project to cerebellum for proprioception
tell me about the visceral afferent nuclues
receives visceral information
Name everything indicated
from the top in clockwise fashion:
posterior gray horn
lateral gray horn
anterior gray horn
anterior nerve root
spinal nerve trunk
anterior ramus
posterior ramus
spinal ganglion
posterior nerve root
Posterior primary rami have how many branches?
2
what are the two branches of pos. primary rami?
lateral (motor) to muscle
medial (sensory) to skin
anterior primary rami can organize into how many different plexi? What are they?
4
cervical plexus C1-C4
brachial plexus C5-T1
lumbosacral plexus L1-S4
coccygeal plexus S4-S5 + 1st coccygeal
external portion of spinal cord is white or gray matter?
white. it is white because of myelin
what form the “tracts” in the spinal cord?
the clusters of axons in the external white matter
what is myelin made out of?
lipid/protein
What are the three ascending (sensory) pathways?
tract of lissauer
posterior white columsn
Ant./Post. spinocerebellar tracts
what does tract of lissauer do? why is it unique?
it is part of the pain pathway.
different from others becasue it has sensation that jumps 1-2 vertebral levels, then cross at the spinothalamic tract and then enter the posterior gray horn
what make up the posterior white columns? what do they do?
fascicularis gracilis (legs)
fascicularis cunetus (arms)
touch, discriminate, touch, vibration, conscious muscle joint sense, proprioception
what do ant./post. spinocerebellar tracts do?
carry proprioception info to the cerebellum
what are the descending pathways?
lateral/anterior corticospinal tracts
reticulospinal tracts
vestibulospinal tracts
rubrospinal tracts
what do lat/ant corticospinal tracts do?
gross motor movement and fine motor, voluntary
what do reticulospinal tracts do?
awake and voluntary movement, reflexes
what does vestibulospinal tract do?
balance traverse teh inner ear and cerebelllum by this tract
fasilitate extensor muscles and inhibit flexor muscles to maintain balance
what do rubrospinal tracts do?
alpha motor neurons facilitate flexor muscles
Are these ascending or descending tracts?
ascending with sensory information to the brain
are these ascending or descending tracts?
descending carrying commands to motor neurons
ventral roots are motor or sensory?
motor
Name the four sections
from top to bottom
somatic sensory nuclei
visceral sensory nucleui
autonomic efferent nuclei
somatic motor nuclei
Name the highlighted areas from top to bottom.
substania gelatinosa
nucleus proprius
dorsal nucleus
intermediolateral nucleus
motor neurons of the anterior horn
what is the principal site of action for SAB?
nerve roots
what do you get with blockade of dorsal roots?
somatic/visceral
sensory
what do you get with blockade of ventral root?
motor
autonomic
What supplies blood to post. spinal cord?
posterior spinal arteries 1/3 of post. spinal cord
radicular arteries other 2/3 of spinal cord
what arteries supply the posterior spinal arteries?
derived from cerebral arterial system with rich supply of collateral flow from the subclavian, intercostal lumbar, and sacral arteries.
what supplies blood to anterior spinal cord?
a singular ant. spinal artery 2/3 of cord
single, segmental branch of radiuclar artery called the artery of adamkiewicz or arteria radiuclaris magna: nearly all of the flow to lower thoracic and lumbar segments.
what is anterior spinal artery derived from and what contributes to it?
derived from both vertebral arteries and transverse down cord in ant. median fissure.
contributions from radicular arteries.
where does ant. spinal artery become extremely small? why is this importnat?
mid to lower thoraic region. Can be a problem if the radicular arteries are occluded
tell me more about admakiewicz artery
supplies lower 2/3 of ant. spinal cord.
damage, ischemia, hypoperfusion or occlusion to this artery can cause anterior spinal artery syndrome.
what is anterior spinal artery syndrome?
flaccid paralysis and variable loss of sensation of pain and temp at and below the level of injury. proprioception and light touch are preserved.
when does ant. spinal artery syndrome occur?
this is a rare syndrome but most common in aortic surgery with prolonged cross clamping or direct injury.
what are other factors that play a role in ant. spinal artery syndrome?
atherosclerosis, prolonged hypotension, and embolic issues
what occurs with disruption of teh cord at the corticospinal tract?
MOTOR PARALYSIS
when do you loose pain and temp at and below injury?
disruption of spinothalamic tract
proprioception and vibratory sensation retained because of intact dorsal columns
post cord can remain intact. sensory fascicularis gracilis intact as well as proprioception. partial complex injury.
ALL is widest at top or bottom?
bottom. so more likely to have cervical disc herniation forward.
“ACDF”
PLL is widest at top or bottom?
top, so more likely to have lumbar disc herniation posteriorly
“lumbar lami and disectomy”
where is the supraspinous ligament the thickest and most broad?
lumbar region
where is ligamentum flavum most think and most thin?
most thin in cervical region, most thick in lumbar region.
what structures does ligamentum flavum attach too? And blend with?
attach to ant. inf. aspect of lamina below
latterally with the joint capsule betwen articular processes
posteriorly with inerspinous ligament
what vessels can be found within the ligamentum flavum?
small vessells from the vertebral plexuses (blood tinge in the syringe)
although rare, the ligamentum flavum sometimes does not totally fuse in the middle. Where does this most offeten occure? (still rare) Why is this importnat?
L1-L2
won’t feel loss of resistance when accessing the epidural space
how far is ligamentum flavum normally from spinous process in lumbar region?
3-4cm
what does the needle feel like when in the ligamentum flavum?
dense/elastic feeling and needle becomes engaged in the tissue
disc height can become smaller in old age, how would this affect spinals or epidurals?
makes the interspace smaller
what can happen to the ligamentum flavum in old age?
it can become calcified
where is epidural space located?
between the periosteal lining of the canal and the dura.
extends from base of skill to the sacral hiatus (S4)
what limits the epidural space on each side?
PLL anteriorly
ligamentum flavum and vertebral pedicles posteriorly
intervertebral foramen laterally
describe the distance between the ligamentum flavum and dura matter
smallest, 3-4mm, where cord is present, so upper lumbar thoracic and cervical,
biggest, 5-7mm, after L2
how far from skin to epidural space?
usually 4-5cm, can be anywhere from 2-9cm so be careful
pressure in epidural space?
slightly negative -1 to -7 cmH20 except in sacral area.
widest and narrowest parts of epidural space?
narrowest at C5 1-1.5mm
widest at L2 5-6mm
where is CSF made?
choroid plexus in the ventricles of the brain. mostly in the 2 lateral ventricles but the 3rd ventricle also contributes
where is CSF absorbed?
arachnoid villi
how much CSF produced per day?
21ml/hr or 500ml a day.
how much CSF present at one time?
about 150ml
30-80ml in spinal subarchnoid space, but it can be much more which would cause a spinal to fail from being too dilute.
what is CSF made of?
ultrafiltrate of blood, contains trace amounts of protein and glucose
specific gravity of CSF?
1.003-1.009 and is isobaric
where does spinal anesthesia work?
ant and post nerve roots, and to a lesser extent on the spinal cord itself.
what do dorsal rami supply?
skin and muscles of the back
how are dermatomes in the face organized?
by ophthalmic, maxillary, and mandibular divisions of the trigeminal nerve
dermatome level of clavicle?
C4
dermatome level of little finger?
C8
dermatome level of nipple?
T4
dermatome level of xiphoid, lower rib cage
T6-T8
dermatome level of umbilicus?
T10
