Spinal Anatomy and Nerve Flashcards
For patients that were receiving therapeutic doses of LMWH, wait_____hours after the last dose before neuraxial procedure
24
For patients that were receiving prophylactic doses of LMWH, wait_____hours after the last dose before neuraxial procedure
12
After performing a neuraxial procedure, when can you restart LMWH?
24 hours after needle insertion for full dose (Or 48-72 for high bleeding risk surgery)
OR 12 hours for ppx dose
If a neuraxial procedure was performed with catheter in place
DO NOT give full dose or BID ppx LMWH with catheter in place ; one may give daily ppx 12 hours after needle insertion.
When may one safely remove catheter after daily LMWH ppx dosing?
12 hours after
After removal of catheter, when to start LMWH?
with ppx dosing, 4 hours after removal; for full dose wait 4 hours or 24 hours after needle placement
dural sac terminates?
S1-S2
conus medullar is terminates?
L1-L2 (so spinal anesthetics are administered L2-L4)
The dura mater is the toughest and outermost layer. In neonates the dura extends to ____, however this also moves more cephalad as a person ages so that it terminates around ___ in a normal adult.
S3; S1-S2
The arachnoid mater also extends to ___ along with the dural sac.
S1-S2
When performing a spinal blockade in an adult, the iliac crest is commonly used as a landmark as it generally corresponds to the level of the ______
L4 interspace (Tuffier’s line)
Spinal anesthesia in an adult is generally administered at the ______interspace as this avoids the spinal cord, yet is still above the level at which the dural sac terminates.
L3-4 or L4-5
conus medullaris ends at ____in adults
L1-L2
conus medullaris ends at ____in newborns.
L3-L4
dural sac ends at _____in newborns
S3-S4
axillary nerve block but is still able to flex their arm at the elbow.
Musculocutaneous was not blocked!
Musculocutaneous N provides innervation to _____muscle and flexion at_____?
biceps; flex at elbow
where does musculocutaneous nerve lie?
laterally between the fascial planes of the biceps brachii and coracobrachialis muscle
intercostobrachial nerve originates from?
T2
when is intercostobrachial nerve indicated?
upper arm tourniquet is required and would not be successful with any brachial plexus block technique.
elbow and wrist extension?
radial N.
addition of bicarbonate to ropivacaine or bupivacaine can cause ?
precipitant to form in solution
Often bicarbonate is added to local anesthetic (often in a 1:10 ratio) to increase the pH of the solution. This increase of pH decreases pain on injection into peripheral tissues and also speeds the onset time of the local anesthetic by increasing the unionized portion of local anesthetic
Lidocaine remains relatively soluble in its unionized form. However ropivacaine and levobupivacaine are not, and therefore it is not recommended to have bicarbonate added for infusion
nerve fiber is responsible for the fastest transmission of nociception?
A- delta fibers “Delta airplane”
fibers responsible for transmission of nociception?
Type A-delta fibers and C fibers
conduct proprioception and motor
A-alpha
transmit mechanical information and information from Meissner corpuscles and Merkel disks. touch and pressure
Type A-beta
Muscle spindles and tone
Type A gamma
two fibers responsible for nociception/pain?
A delta and type C dorsal
Differential blockade begins with
B fibers, then A, then C. Recovery is in reverse order.; *A mnemonic for differential blockade is “Sympathetic People Matter”: Sympathetics > Pain > Motor for neuraxial blockade levels.
For neuraxial blocks,________ nerve fibers are blocked by the lowest concentration of local anesthetic followed by nerve fibers responsible for pain/touch and finally motor function.
sympathetic
slowest conduction velocity and are not sensitive to nerve blockade as they are unmyelinated.
C fibers
epidural anesthesia may cause?
increased peristalsis=> Tonic inhibitory sympathetic control (T6-L2) predominates, but parasympathetic activation increases contractility. Therefore, sympathectomy induced by epidural or spinal analgesia results in increased gut motility (B), especially those involving epidural catheter placement at T12 or higher.
Sympathectomy induced by epidural anesthesia results in _______, especially those involving epidural catheter placement at T12 or higher.
increased peristalsis
Tx for N/V caused by spinal?
nopposed parasympathetic (vagal) activity after sympathetic blockade causes increased peristalsis of the gastrointestinal tract, which can lead to nausea. For this reason, atropine is nearly universally effective in treating nausea associated with neuraxial blockade. G
At which of the following spinal levels does the great radicular artery MOST commonly originate?
T9-T12
Spinal Cord Perfusion Pressure (SCPP) = ?
= MAP - Intrathecal Pressure or CSF pressure (SCPP = MAP - CSF pressure). The two most common ways to improve SCPP during aortic surgery are to increase the MAP and reduce CSF pressure using a lumbar CSF drain.
CPP =
MAP - ICP applies to the spinal cord and the principle remains the same as intracranial hypertension.
Blood supply to the _______ of the spinal cord (wherein the motor tracts are located) is provided by the SINGLE anterior spinal artery (ASA)
anterior two-thirds
what is ASA syndrome?
irreversible spinal cord damage, paraplegia, and loss of bowel and bladder function,
tx of ASA syndrome?
SCPP can be increased by increasing MAP > 90 mm Hg through the administration of vasopressors and reducing CSF pressure < 10 mm Hg by CSF drainage.
Blood supply to the posterior _____of the spinal cord is provided by the TWO posterior spinal arteries (PSA)
1/3
ASA= motor PSA= ?
sensation and proprioception in the dorsal columns.
which artery gives rise to the single ASA?
vertebral!
which artery gives rise to the PSA?
posterior inferior cerebellar arteries from the vertebral arteries give rise to two PSAs.
In ASA syndrome what is preserved?
In anterior spinal artery syndrome, there is loss of motor, temperature, and pain function. Proprioception and vibratory senses are preserved.
pain and temp
(lateral spinothalamic tract)
corticospinal tract
motor
3 mechanisms for Subarachnoid anesthesia causing hypotension???
1- arterial dilation 2/2 loss of sympathetic tone
2-venodilation
3-bradycardia- higher blocks are associated with brady (cardiac acc fiber T1-T4); parasympathetic dominance and/or the Bezold-Jarisch reflex
Bezold-Jarisch cardiovascular reflex
parasympathetic-mediated reflex occurs when stretch receptors located mainly in the left ventricle respond to an acute decrease in left ventricular preload. The result is bradycardia and reduced contractility (and resultant hypotension). This reflex is thought to occur to allow the ventricle additional time to fill and increase preload
carotid sinus baroreceptor response to hypotension
increased heart rate and contractility
best nausea treatment after HIGH SPINAL?
atropine
RFs for N/V after spinal?
high block (above T5), hypotension, opioid administration, and a history of motion sickness
Treatment if LAST?
1- supportive measures: 100% oxygen, airway management, avoid hypoxia and acidosis, tx seizures w benzos; facility with Cardiopulm bypass should be altered
2- IV lipid emulsion 20%, bolus 1.5ml/kg over 1 min, infusion of .25
3- tx cardiac arrhythmia ; AVOID local anesthetics, beta blockers, calcium channel blockers, and vasopressin. In addition, it is recommended to decrease each dose of epinephrine to < 1 mcg/kg. Amiodarone is the preferred treatment for ventricular arrhythmias.
Differential blockade in a 23F undergoing C section- getting spinal
The order of susceptibility to local anesthetics is small myelinated (A-delta, A-gamma) > large myelinated (A-alpha, A-beta) > unmyelinated (C).
Sympathetic people matter
Spinal anesthesia causes _____ GI secretions
INCREASED
Spinal anesthesia may cause what effects?
decreased hearing; hypothermia, increased GI secretions, increased vent response to hypercapnia, and PDP HA
acute circumoral numbness and tinnitus immediately after a regional procedure- what was blocked??
intercostal block
intravenous > intercostal blocks > caudal > epidural > brachial plexus > intravenous regional > lower extremity blockade. What is the mneumonic?
Mnemonic - IICEBALLS: intravenous > intercostal > caudal > epidural > brachial plexus > axillary > lower limb > subcutaneous
___ blocks are associated with the highest blood levels of local anesthetic following completion of the block.
Intercostal blocks
Subcutaneous infiltration of the entire width of the medial axillary fossa will block which of the following nerves?
Intercostobrachial
Intercostobrachial will block what?
medial axillary fossa?
lateral ante brachial cutaneous block will block what?
ubcutaneous injection across the forearm just below the elbow crease
Musculocutneous is blocked by injecting where?
coracobrachilias muscle
ankylosing spondylitis??
associated with difficult airway and epidural hematoma secondary to epidural attempts, but is not associated with peripheral neuropathy.
Why are pt with ankylosing spondylitis at increased risk of epidural hematoma ?
b/c they are frequently on NSAIDS pain meds leading to plt dysfunction and increase bleeding risk
caudal epidural, which of the following structures should a needle traverse just prior to the epidural space
sacrococcygeal ligament
why is caudal anethesia difficult in adults?
sacrococcygeal ligament is calcified!
medial calf is sensory from where?
femoral nerve
where does saphenous N originate from ?
femoral N
25F spinal anesthesia- become Brady, what are etiologies
decreased cardia preload; high baseline vagal tone, anesthetic level higher than T5
spinal bock results in a sympathectomy 2 levels higher than the ____level
sensory
what factors affect height of a block?
1- position
2-baricity
3-dosage (mg)
Which of the following factors, within typical ranges, has the LEAST effect on the spread of neural blockade with spinal anesthesia?
drug volume
what does drug volume have the greatest effect on?
epidural anethesia!
minimal effect in @spinal
numbness and paresthesias along the medial lower leg
Saphenous N
which pt are most at risk for new or worsening neurologic injury from a neuraxial anesthetic?
space-occupying extradural lesions or those that reduce the cross-sectional area of the spinal cord, such as spinal stenosis
carotid body vs sinus?
carotid body=chemoreceptor
carotid sinus=baroreceptors- o hypotension and bradycardia,
carotid body vs sinus? mnemonic?
Think “sinus pressure” to help differentiate the roles of the carotid sinus and carotid body.
epidural, paramedian approach?
superficial to deep?
3:
skin, subcutaneous, lig flavum
epidural, midline approach?
skin, subcutaneous tissue, supraspinous ligament, interspinous ligament, and then ligamentum flavum.
Lidocaine infiltration causes inhibition of baroreceptor output from the carotid sinus and would result in ?
hypertension and tachycardia.
Which of the following will MOST AFFECT the epidural spread of local anesthetics?
Volume
Epidural effect..
concentration affects- intensity of block
speed of injection affects- onset
why is dura matter more permeable in elderly?
ncreased number of arachnoid villi. Be sure to reduce epidural dosing in elderly!
Oculocardiac reflex?
When is it seen and what is it>
children undergoing strabismus surgery. The reflex can result in bradycardia, arrhythmia, and/or cardiac arrest. The stimulus is usually traction on the extraocular muscles or pressure on the eyeball.
Afferent pathway= trigeminal nerve (CN V)
Efferent= vagus (CNX)
Afferent pathway= trigeminal nerve (CN V)
Efferent= vagus (CNX), leading to Brady
Oculocardiac reflex- Stimuli at the eye -> ciliary ganglion -> ophthalmic division of trigeminal nerve -> Gasserian ganglion -> trigeminal nucleus -> vagus nerve -> bradycardia.
base of the palatoglossal fold
glossopharyngeal N
where is glossopharyngeal nerve blocked
palatoglossal folds
transtracheal injection
recurrent laryngeal nerve
superior laryngeal nerve can be blocked by either injection at the ____ OR_____
horn of the hyoid bone or by placing a pledget in the pyriform sinus.
Which muscle is the only intrinsic muscle of the larynx not innervated by the recurrent laryngeal nerve
cricothyroid muscle
Which of the following nerves innervates the cricothyroid muscle?
external branch of SLN
tensor of vocal cords during phonation
bilateral RLN injury will results in what?
vocal cords will assume a position midway between abduction and adduction (SLN innervation only)- stridor and rest distress
unilateral RLN injury will results in what?
difficulty with phonation but no resp distress
what innervates the pharynx and is the afferent (SENSORY) limb of the gag reflex.
glossopharyngeal nerve
what nerves are blocked for fiberoptic ?
glossopharyngeal nerve, SLN, and RLN
SENSATION to the area of the vocal cords and trachea; epiglottis to the vocal cords.
RLN, internal
Spread of local anesthetic within the CSF is primarily determined by?
baricity of the local anesthetic solution and then the patient position when hypo or hyperbaric solutions are used,
What imaging would be the BEST first choice for diagnosis of a retained epidural catheter fragment
CT
Which of the following is decreased the MOST from lumbar or low thoracic epidural anesthesia with a local anesthetic?
Peak expiratory pressure
low thoracic epidural
PEP
systemic absorption of local anesthetics?
intravenous > tracheal > intercostal > caudal > paracervical > epidural > brachial plexus > sciatic/femoral > subcutaneous.
ICEBaLLS: Intercostal, Caudal, Epidural, Brachial plexus, Lower Limb, Subcutaneous.
BICEPS: Blood, Intercostal, Caudal, Epidural, Plexus (brachial), Sciatic, Subcutaneous.
ICEBaLLS: Intercostal, Caudal, Epidural, Brachial plexus, Lower Limb, Subcutaneous.
BICEPS: Blood, Intercostal, Caudal, Epidural, Plexus (brachial), Sciatic, Subcutaneous.
mnemonic for order of absorption
Which local anesthetics has the LOWEST cardiac-to-CNS dose toxicity ratio and the HIGHEST relative potency for cardiac toxicity?
bupi
local anesthetics with greatest cardiac toxicity?
bupi
how do local anesthetics produce direct and indirect cardiac toxicity?
through blockage of the INTRACELLULAR portion of cardiac SODIUM ion channels.
afferent limb laryngospasm reflex?
internal branch oof superior laryngeal N
least amount of beam rays during ultrasound?
BLOOD
afferent limb of the gag reflex.?
glossopharyngeal nerve (cranial nerve IX)
Which part of the myocardial region is supplied by RCA?
Inferior wall of the left ventricle.
RCA innervation?
The right coronary artery (RCA) supplies the anterior and posterior RV, the RA, the upper atrial septum, the posterior third of the interventricular septum, and the inferior and posterior LV
LCA innervation?
The left main coronary artery provides blood supply to the apices of the left ventricle (LV) and right ventricle (RV), the anterolateral LV, and the anterior two-thirds of the interventricular septum.
coronary sinus drains into the ?
R atrium
great cardiac vein is located__?
with the LAD
Anterior cardiac vein is located__?
with the RCA
Middle cardiac vein is located__?
associated with the posterior descending coronary artery (PDA)
Which of the following structures are MOST likely traversed during a paramedian thoracic epidural?
skin, subcutaneous fat, paraspinous muscles, and ligamentum flavum.
afferent limb for the laryngospasm reflex?
internal branch of SLN
The recurrent laryngeal nerve (RLN) and the SLN are branches of the ___nerve?
vagus nerve (CN X)
larynx is innervated by the____N.
vagus
what nerve provides sensation to pharynx, middle ear, posterior one-third of the tongue (including taste buds), and the carotid body and sinus.
glossopharyngeal
sensation to the larynx from the glottis and below?
RLN
3-year-old male develops an episode of laryngospasm during emergence from general anesthesia. Which of the following descriptions BEST describes this mechanism?
Laryngospasm is a protective airway reflex resulting in closure of the true and false vocal cords or the true cords only
Laryngospasm occurs during
stage 2 (excitation phase)
What may result in a greater overlap of the IJV and the common carotid artery (CCA). ?
Excessive rotation of the patient’s head toward the contralateral side during positioning for internal jugular vein (IJV) cannulation
The transverse process of ____is the major landmark for stellate ganglion blockade
C6
Bilateral RLN injury results in?
results in airway obstruction requiring tracheostomy.
Left unilateral vocal cord paralysis may occur after?
PDA ligation as the left recurrent laryngeal nerve loops under the aortic arch in the same vicinity.
weak voice, hoarseness, and paramedian (adduction) position of the ipsilateral vocal cord
Unilateral recurrent laryngeal nerve injury
paramedian spinal- order of structures?
skin -> subcutaneous tissue -> muscle -> ligamentum flavum -> epidural space -> dura mater -> arachnoid mater -> subarachnoid space.
toxic doses of local anethestics: lidocaine, bupivicaine, and ropi
Lidocaine (plain): 5 mg/kg Lidocaine (with epi): 7 mg/kg Bupivacaine (plain): 2.5 mg/kg Bupivacaine (with epi): 3 mg/kg Ropivacaine (plain only): 3 mg/kg Chloroprocaine (plain only): 12 mg/kg
BEST initial treatment for post spinal backache?
Acetameophen/tylenol
