Lower extremity blocks Flashcards
Which nerves arise from the lumbar plexus?
a. pudendal
b. femoral
c. obturator
d. posterior femoral cutaneous
e. lateral femoral cutaneous
f. sciatic
B, C, E
femoral, obturator, lateral femoral cutaneous nerve
The lumbar plexus arises from
the anterior rami of L1-L4 with an occasional contribution from T12
What are the six nerves that arise from the lumbar plexus?
iliohypogastric (I)
Ilioinguinal (invariably)
Genitofemoral (get)
lateral femoral cutaneous (lazy)
Obturator (on)
femoral (Fridays)
The iliohypogastric nerve arises from
L1 (“two from one”
The ilioinguinal nerve arises from
L1 (“two from one”)
The genitofemoral nerve arises from
L1 & L2 (two from two)
The lateral femoral cutaneous nerve arises from
L2 & L3 (two from two)
The obturator nerve arises from
L2 +L3+ L4 (two from three)
The femoral nerve arises from
L2+L3+L4 (two from three)
Where does the sciatic nerve originate from?
L4-S3
Where does the posterior femoral cutaneous nerve originate from?
S1-S3
The coccygeal plexus gives rise to the following nerves:
pudendal
inferior anal
perineal
The pudendal, inferior anal, and perineal nerves all arise from
S4-coccyx
Describe the transition of the femoral nerve down the leg.
femoral nerve–> saphenous nerve in the leg–> saphenous nerve at the ankle
Describe the transition of the sciatic nerve in the leg:
becomes the common peroneal and tibial nerve
The common peroneal nerve becomes these nerves at the ankle:
superficial peroneal nerve, deep peroneal nerve, and sural nerve
The tibial nerve becomes these nerves at the ankle:
the sural nerve & the posterior tibial nerve
The lumbar plexus forms posterior to _______ and anterior to _______
the psoas and anterior to the quadratus lumborum muscle
What is the sensory and motor innervation of the lateral cutaneous femoral nerve?
motor- none
sensory: lateral upper leg
What is the sensory and motor innervation of the femoral nerve?
motor-anterior branch: sartorius
motor-posterior branch: quadriceps
sensory: anterior thigh
This nerve is often injured in patients who undergo extensive pelvic surgery.
obturator nerve
What is the sensory and motor innervation of the obturator nerve?
sensory: distal inner thigh and part of hip
motor: hip adductors
The largest nerve in the body is the
sciatic nerve
What is the sensory and motor innervation of the sciatic nerve?
Motor: posterior thigh and lower leg
sensory: lower leg & foot
The ______ nerve supplies sensory innervation to the posterior aspect of the thigh.
Posterior femoral cutaneous nerve
The psoas compartment block anesthetizes all of the following nerves EXCEPT the:
a. saphenous
b. sciatic
c. obturator
d. lateral femoral cutaneous
B.
The psoas compartment block is also known as the
lumbar plexus block
The psoas compartment blocks targets the three major nerves of the lumbar plexus including the
femoral
obturator
and lateral femoral cutaneous nerves
The psoas compartment block is useful when
neuraxial anesthesia is contraindicated and/or anesthesia to one lower extremity is preferred
Local anesthetic volumes greater than 20 mLs for the psoas compartment block increase the risk of
bilateral spread and contralateral limb involvement
creating a bilateral sympathectomy
_____ is a contraindication to the psoas block
Coagulopathy b/c of high complication rates of retroperitoneal hematoma and renal capsular injection
The adductor canal block may be used because
it is a sensory block and prevents quadricep weakness
What is the three in one block?
different approach to a femoral block with the intent to block three nerves (femoral, obturator, lateral cutaneous) with one injection
greater volume of 30 mLs is needed
similar to a femoral block but trying to force spread of the LA more proximal
Describe the dosage for continuous femoral nerve blocks.
8-10 mL/hr for up to 48 hours with 0.2% ropivacaine or 0.25% bupivacaine
The femoral triangle is composed of
inguinal ligament
sartorious muscle
adductor longus muscle
Pick the statements that BEST describe the proper technique for performing a fascia iliaca compartment block.
a. LA is deposited anterior to the iliopsoas muscle
b. ultrasound is required
c. two pops should be felt before injecting local anesthetic
d. LA should be deposited between the fascia iliaca and fascia lata
A & C
The fascia iliaca block can be considered for
hip surgery; as well as femur and knee surgery and hip fractures
Which peripheral nerve block can be combined with a sciatic nerve block to enhance tolerance of a lower leg tourniquet?
a. common peroneal
b. saphenous
c. posterior tibial
d. sural
B. saphenous
The sciatic nerve provides motor innervation to the:
a. semitendinosus
b. sartorius
c. biceps femoris
d. quadriceps
A & C
Stimulation of the tibial nerve in the popliteal fossa causes:
a. plantar flexion and inversion of the foot
b. plantar flexion and eversion of the foot
c. dorsiflexion and inversion of the foot
d. dorsiflexion and eversion of the foot
a. plantar flexion and inversion of the foot
What are the five nerves of the ankle?
Sural nerve
tibial nerve
superficial peroneal nerve
deep peroneal nerve
saphenous nerve
Which nerves of the ankle are purely sensory?
sural, superficial, and saphenous (easy to remember b/c they are the only ones that begin with a ‘s’)
What is the elicited motor response of the tibial nerve?
inversion + plantar flexion
What is the elicited motor response of the deep peroneal nerve?
eversion + dorsiflexion
Injecting a ring of local anesthetic from the midpoint of the distal tibia toward the inferior border of the medial malleolus will most likely anesthetize the:
a. sural nerve
b. saphenous nerve
c. tibial nerve
d. superficial peroneal nerve
b. saphenous nerve
