LE blocks Flashcards
lumbar plexus originates from anterior rami of
L1-L4
sacral plexus originates from posterior rami of
L4-S4
draw the lumbar plexus
draw the sacral plexus
six branches of lumbar plexus in order
iliohypogastric
ilioinguinal
genitofemoral
lateral femoral cutaneous
obturator
femoral
lateral femoral cutaneous
arises from
forms
courses
arises from L2-3 posterior divisions
forms the midpoint of the psoas muscle
courses laterally along the anterior iliac spine, and then passes under the lateral border of the inguinal ligament
the femoral nerve
arises from
forms
courses
arises from posterior divisions of L2-4
forms near the middle and lower 1/3 of psoas muscle
courses distally through groove created by psoas major and iliacus muscles under inguinal ligament lateral to the femoral artery and anterior to the ilipsoas muscle
the femoral nerve divides into
anterior and posterior branches
the posterior branch gives rise to one terminal branch (saphenous nerve)
the saphenous nerve courses through adductor canal and becomes superficial at the knee
the sacral plexus forms anterior to
the psoas major
five major branches of sacral plexus include
superior gluteal
inferior gluteal
posterior cutaneous
pudendal
sciatic
the sciatic nerve arises from
courses through
arises from L4-S3 (comprised of tibial and common fibular trunks)
courses through sacrosciatic foramen (underneath piriformis muscle) and descends between major trochanter and ischial tuberosity
the sciatic nerve divides into 2 branches (which branches and where does it divide)
divides into tibial nerve and common peroneal nerve (fibular nerve) at proximal popliteal fossa
the tibial nerve
arises from
course through
sacral nerve (anterior branch of L4-S3)
courses medially through popliteal fossa distally and between medial and lateral heads of gastrocnemius muscle
the tibial nerve gives rise to what
1 terminal branch (posterior tibial nerve)
the common peroneal nerve
arises from
courses through
sacral nerve (posterior branches of L4-S3)
courses laterally over head of the fibula before dividing into deep and superficial peroneal nerves
the common peroneal nerve gives rise to what branches
3 terminal branches:
deep peroneal nerve
superficial peroneal nerve
sural nerve
what are the 5 terminal nerves at the ankle
saphenous (only one from femoral)
superficial peroneal
deep peroneal
sural
posterior tibial
innervation of A, B, C, D in this image
A: LFCN
B: obturator
C: saphenous
D: superficial peroneal
dermatome L2
sensory region
medial upper thigh
dermatome L3
sensory region
medial lower thigh
dermatome L4
sensory region
lateral thigh and anterior knee
dermatome L5
sensory region
lateral lower leg and top of foot
dermatome S1
sensory region
posterior leg (more lateral)
dermatome S2
sensory region
posterior leg (more medial)
peripheral nerves of LE that are only sensory
LFCN
saphenous
sural
peripheral nerves of LE that are combined motor and sensory
femoral
obturator
posterior tibial
deep peroneal
superficial peroneal
sensory region of femoral nerve
anterior branch -> anterior thigh
posterior branch-> saphenous nerve->medial aspect of lower leg
sensory region of obturator nerve
articular branches of hip joint
medial thigh
sensory region of LFCN
lateral thigh to knee
sensory region of pudendal nerve
perineum
anal canal and external sphincter
sensory region of posterior femoral cutaneous nerve
posterior hip to mid calf
sensory region of posterior tibial nerve
plantar surface of foot
sensory region of superficial peroneal nerve
dorsal surface of foot
sensory region of deep peroneal nerve
web space between big toe and second toe
sensory region of sural nerve
lateral aspect of foot
motor function of femoral nerve
hip–> flexion and lateral rotation
knee–>extension and flexion
motor function of obturator nerve
motor adduction, flexion, extension
motor function of LFCN
none
motor function of pudendal nerve
sphincter tone
motor function of sciatic nerve
hip: extension
knee: flexion
motor function of tibial nerve
toe: abduction, adduction, extension, flexion
ankle: plantar flexion
motor function of superficial peroneal nerve
ankle->eversion
motor function of deep peroneal nerve
ankle–>dorsiflexion and inversion
review osteotomes
what nerves does the PENG block target
femoral nerve
accessory obturator nerve
obturator nerve
key anatomic landmarks for the PENG (pericapsular nerve group) block include
femoral vein, artery, nerve (m to l)
iliopsoas muscle and tendon
anterior inferior iliac spine (AIIS)
iliopubic iminence (IPE)
the location of the PENG block decreases risk of quads weakness because
of the distance from the femoral nerve. femoral nerve is spared because injection happens deep to iliopsoas muscle
what is the PENG block indicated for
what nerves it targets
hip fractures or arthroplasty
targets nerves from lumbar plexus that supply sensory innervation to hip capsule
when combined with a LFCB, the PENG block provides an alternative for
femoral and fascia iliaca block
USG PENG block technique
- place patient in supine position with slight external rotation of extremity
- place low frequency curvilinear array transducer (2-5mHz) in transverse orientation on the proximal thigh distal to the inguinal ligament.
- the hyper echoic femur provides contrast. slide transducer cephalad towards level of rounded acetabulum to level of anterior inferior iliac spine and pubis ramus are visible.
- at this level, visualize femoral artery, vein, and nerve superior to iliopsoas muscle
- the iliopubic eminence (IPE) formed by junction of ilium and pubis creates a floor. note hyper echoic psoas tendon is immediately superior to IPE
- insert 20g tuohy needle. larger diameter facilitates injection in tight space between psoas and IPE
complications of PENG
- injecting straight into psoas may facilitate muscle weakness
- inserting needle above inguinal ligament and advancing too medially increases risk of injecting into pelvic cavity and puncturing vital structures (ex ureter)
fascia iliaca block targets which 3 nerves
femoral, obturator, LFCN
indications for fascia iliaca block
surgical procedures involving femur, quadriceps, knee
acute pain management for hip fx
-when compared to lumbar plexus block, provides faster and more consistent block of LFCN and femoral n
USG fascia iliaca block
(doesn’t require nerve stimulation)
1. place high frequency linear array transducer in saggital orientation at anterior superior iliac spine (ASIS) and slide to brim of the pelvis
2. rotate caudal end of transducer slightly lateral to bring sartorious and internal oblique muscles (which form bow tie) into view
3. insert 22g 9cm B bevel needle using an in plane approach 1cm cephalad to the inguinal ligament in a cranial dorsal direction until it pierces the inguinal ligament
4. using hydro dissection, inject 1-2mL of NS to separate fascial from iliacus muscle.
5. following negative aspiration, inject 1-2mL to separate fascia iliaca from iliopsoas muscle.
6. inject 40mL LA in 5mL increments
landmark fascia iliaca block
- place patient in supone position
- at the level of inguinal ligament, draw a line from anterior superior iliac spine (ASIS) to the pubic tubercle and divide it into thirds
- insert the needle 1cm caudal from the line separating the lateral and middle third
- insert 22g 5cm B bevel needle perpendicular to the skin
- you should feel a loss of resistance as the needle passes through the fascia lata. advance until you feel a second loss of resistance through fascia iliaca
- following negative aspiration, inject 40mL in 5mL increments
- apply manual pressure distal to insertion site to prevent caudal spread of LA
complications of fascia iliaca block
LA injected above fascia iliaca results in failed or incomplete block
d/t large volume of LA injected, you may see quad weakness and the possibility of LAST
borders of the femoral triangle for the femoral nerve block
corners look like a SAIL so borders are
sartorious
adductor longus
inguinal ligament
indications for femoral nerve block
surgical anesthesia and analgesia for procedures involving hip, femur, quads, knee
offers reliable acute pain management for hip fractures
USG FNB
- place patient supine with slight external extremity rotation
- place high frequency linear array transducer (10-12 MHz) in transverse orientation at inguinal crease
- ID major anatomical landmarks. FN appears hyper echoic below fascia lata and iliaca
- prep, drape, insert a 22g 5cm B bevel needle using in plane approach through fascia lata and iliaca just lateral to the femoral artery. direct needle inferior to aspect of nerve to elicit a response.
- following negative aspiration, inject 20-30mL of LA in 5mL increments
landmark FNB
- place patient in supine with slight external rotation
- palpate femoral artery from ASIS to pubic tubercle
- place x 1cm lateral and 1cm inferior to inguinal ligament
- prep, drape, skin wheal, insert 22g 5cm B bevel needle in a slightly cephalad direction.
- set nerve stimulator to 1mA and go until you see patellar snap. 2 pops is fascia lata and iliaca. advance the needle and ensure patellar snap at .3mA to ensure optimal location
- inject 20mL in 5mL increments.
what happens if you get inner thigh twitching during FNB
you are activating sartorious muscle. withdraw needle and advance slightly laterally.
complications of FNB
because of block of femoral artery, this FNB adds to falls post LE surgery
uncommon but vascular puncture and nerve injury
adductor canal block femoral triangle boundaries include
inguinal ligament (base)
medial aspect of sartorius (medial aspect)
medial aspect of adductor longus lateral side of triangle)
(adductor canal originates at apex of femoral triangle)
indications for ACB
anterior cruciate ligament repair
medial collateral ligament repair
patella fracture
vein stripping and harvesting
supplement to sciatic block or foot/ankle surgery
USG ACB
- place patient supine with slight external rotation of extremity
- position high frequency linear array transducer (10-12mHz) in transverse orientation at mid to distal 2/3 of thigh
- ID femoral artery inferior to sartorius and transducer. saphenous nerve is hyper echoic and anterolateral to artery
- prep and drape, do skin wheal, use 22g 9cm B bevel needle using an in plane approach to the fascial plane between VM and sartorius.
- following negative aspiration, inject 15-20mL in 5mL increments.
complications of ACB
quads weakness is more likely with proximal injections and ones that exceed 20mL
vascular puncture, nerve injury, and myotoxicity if injected inside muscle.
key anatomic land marks of popliteal nerve block includes
popliteal artery and vein
biceps femoris, semitendinosus, and semimembranosus muscles
bifurcation of sciatic nerves into common tibial and peroneal nerves.
indications for popliteal nerve block
provides pain control for below the knee surgical procedures such as ankle, achilles tendon, foot surgeries. also helps manage acute pain
when combined with saphenous nerve block, provides complete coverage of LE below knee
USG popliteal nerve block
- on US, TN appears hyper echoic. dorsal and lateral to artery and vein in popliteal fossa.
- prep, drape, insert 22g 9cm B bevel needle using in plane approach until tip is at bifurcation of two branches. advance needle further to medial border of TN. following negative aspiration, inject 10mL circumferentially around TN. slowly withdraw needle to lateral edge of CPN. following negative aspiration, inject 10mL around CPN.
landmark popliteal nerve block
- with the patient in prone position and with slight flexion, draw a line from biceps femoris medially to semitendinosis at popliteal crease.
- at midpoint, extend a perpendicular line approx 10cm cephalad. needle insertion point is 1cm lateral to this line
- prep, drape, skin wheal at insertion site. 22g 9cm B bevel needle attached to nerve stimulator through wheal pointing slightly cephalad. set nerve stimulation at 2 Hz and 1mA and advance until either plantar flexion (TN) or dorsal flexion (CPN) motor response is initiated. do this until you get to .3 mA
- inject 20mL in 5mL increments.
TIPPED pneumonic for tibial and peroneal
tibial inversion plantar flexion
peroneal eversion dorsiflexion
complications of popliteal nerve block
nerve injury and inadvertent vascular puncture
foot drop and numbness of sole may lead to patient falls
sensory innervation of stapnehous nerve on the foot
medial aspect of ankle and foot
sensory innervation of the sural nerve on the foot
posterior portion of heel
lateral sole of foot
achilles tendon above ankle
sensory innervation of superficial peroneal nerve on foot
dorsum of foot
sensory and motor innervation of deep peroneal nerve on foot
sensory: lateral side of great toe (hallux). medial side of second digit
motor: eversion and dorsiflexion
sensory and motor innervation of posterior tibial nerve on foot
sensory: sole of foot
motor: inversion and plantar flexion
the one nerve in the foot that does not travel near a vascular structure
the superficial peroneal
posterior tibial USG block
- place transducer in transverse orientation just above medial malleolus along medial aspect of the leg
- insert 22g B bevel block needle in plane (posterior to anterior) and deep to nerve vessels
- after negative aspiration, inject 3-5mL of LA
posterior tibial land mark block
- draw a line connecting superior portion of medial malleolus and achilles tendon.
- prep, drape, palpate posterior tibial artery. if its palpable, insert needle perpendicular to the skin just posterior to the tibial artery
- if the patient c/o parasthesia, inject 5mL LA and slowly withdraw needle while injecting 3 more LA.
- if theres no paresthesia, advance the needle until it contacts medial malleolus and then withdraw 2-3mm. after negative aspiration, inject 5-8mL LA as you slowly withdraw the needle.
USG sural nerve block
- position patient in supine position
- apply tourniquet around proximal tibia to dilate lesser saphenous vein
- prep, drape, place transducer in transverse orientation 1cm cephalad to lateral malleolus. you’ll image the LSV in cross section
- at this level, may be challenging to ID sural nerve. insert 22g B bevel needle in plane (posterior to anterior) just inferior to LSV
- after negative aspiration, inject 3-5mL LA
landmark sural nerve block
- draw horizontal line from superior aspect of lateral malleolus to achilles tendon.
- prep, drape, insert needle in plane between achilles tendon and lateral malleolus
- after negative aspiration, inject 5mL LA as you slowly withdraw the needle.
- needle must reach superior border of lateral malleolus to anesthetize sural nerve.
USG deep peroneal nerve block
- position patient supine
- prep and drape and place transducer in traverse orientation 1-2cm above medial malleolus at level of extensor retinaculum.
- visualize deep peroneal artery and veins in cross section and use these as a reference to ID hyper echoic nerve which you’ll see lateral or anterior to the artery
- insert 22g B bevel needle in plane (lateral to medial) to the inferior border of the nerve
- after negative aspiration inject up to 3-5mL LA elevating nerve off of the bone
landmark deep peroneal nerve block
can block deep peroneal, superficial peroneal, and saphenous without removing the needle
1. with patient in supine position, draw a line from the medial malleolus to the superior border of the lateral malleolus across anterior aspect of ankle
2. prep, drape, ask patient to dorsiflex foot, bringing tendons of anterior tibial and long muscles of the great toe into view
3. insert needle perpendicularly into skin at midpoint between two tendons through the fascia.
4. advance the needle until you elicit paresthesia. confirm negative aspiration and slowly inject 5mL LA
5. if you dont elicit parasthesia, advance needle until you hit tibia then slightly withdraw it
6. after negative aspiration inject 5mL LA
7. inject additional 3mL as you slowly withdraw from fascia
superficial peroneal USGRA
- position patient in supine position
- prep, drape, place transducer in transverse orientation approx 5cm proximal to lateral malleolus
- superficial peroneal nerve appears as small hyper echoic structure in SQ tissue in groove created by extensor digitorum and peroneus brevis longus muscle over fibula
- insert 22g B bevel block needle in plane (lateral to medial) towards inferior aspect of the nerve
- after negative aspiration, inject 3-5mL observing for circumferential spread
landmark superficial peroneal nerve
after blocking deep peroneal nerve and without removing needle from skin, redirect needle tip towards inferior border of lateral malleolus in SQ tissue and block superficial peroneal nerve
as you withdraw needle towards midline, inject 5mL LA into SQ tissue creating wheal under skin
saphenous USGRA
- position patient supine with slight external rotation of extremity
- prep, drape, apply tourniquet on proximal calf to better appreciate greater saphenous vein.
- place transducer in transverse orientation 5-10cm proximal to medial malleolus
- using GSV as landmark, ID stapnehous nerve medially as small hyper echoic structure
- insert 22g B bevel block needle in plane (lateral to medial) inferiorly to nerve and medial to GSV
- following negative aspiration, inject 3-5mL LA while observing for circumferential spread
landmark saphenous
after blocking deep peroneal and superficial peroneal, return to midpoint without removing needle and redirect to inferior border of medial malleolus.
2. at this level, find saphenous nerve in SQ tissue adjacent to saphenous vein
3. after negative aspiration, inject 5mL LA beginning at medial malleolus
4. as you withdraw needle toward midpoint, inject an additional 3mL of LA
complications of foot blocks
avoid large volumes of LA to not incite compression injury and ischemia
4/5 nerves course near vascular structures so big oopsies if you get into one of those and bleeding hematoma or LAST happens
best way to determine adequacy of FNB? ask patient to
knee extension (because successful block mediates quadriceps weakness)
which 3 ankle blocks can be done altogether without taking needle out
deep peroneal
superficial peroneal
saphenous
