Lower extremity blocks

Question 1

Which nerves arise from the lumbar plexus?
a. pudendal
b. femoral
c. obturator
d. posterior femoral cutaneous
e. lateral femoral cutaneous
f. sciatic

Answer 1

B, C, E
femoral, obturator, lateral femoral cutaneous nerve

Question 2

The lumbar plexus arises from

Answer 2

the anterior rami of L1-L4 with an occasional contribution from T12

Question 3

What are the six nerves that arise from the lumbar plexus?

Answer 3

iliohypogastric (I)
Ilioinguinal (invariably)
Genitofemoral (get)
lateral femoral cutaneous (lazy)
Obturator (on)
femoral (Fridays)

Question 4

The iliohypogastric nerve arises from

Answer 4

L1 (“two from one”

Question 5

The ilioinguinal nerve arises from

Answer 5

L1 (“two from one”)

Question 6

The genitofemoral nerve arises from

Answer 6

L1 & L2 (two from two)

Question 7

The lateral femoral cutaneous nerve arises from

Answer 7

L2 & L3 (two from two)

Question 8

The obturator nerve arises from

Answer 8

L2 +L3+ L4 (two from three)

Question 9

The femoral nerve arises from

Answer 9

L2+L3+L4 (two from three)

Question 10

Where does the sciatic nerve originate from?

Answer 10

L4-S3

Question 11

Where does the posterior femoral cutaneous nerve originate from?

Answer 11

S1-S3

Question 12

The coccygeal plexus gives rise to the following nerves:

Answer 12

pudendal
inferior anal
perineal

Question 13

The pudendal, inferior anal, and perineal nerves all arise from

Answer 13

S4-coccyx

Question 14

Describe the transition of the femoral nerve down the leg.

Answer 14

femoral nerve–> saphenous nerve in the leg–> saphenous nerve at the ankle

Question 15

Describe the transition of the sciatic nerve in the leg:

Answer 15

becomes the common peroneal and tibial nerve

Question 16

The common peroneal nerve becomes these nerves at the ankle:

Answer 16

superficial peroneal nerve, deep peroneal nerve, and sural nerve

Question 17

The tibial nerve becomes these nerves at the ankle:

Answer 17

the sural nerve & the posterior tibial nerve

Question 18

The lumbar plexus forms posterior to _______ and anterior to _______

Answer 18

the psoas and anterior to the quadratus lumborum muscle

Question 19

What is the sensory and motor innervation of the lateral cutaneous femoral nerve?

Answer 19

motor- none
sensory: lateral upper leg

Question 20

What is the sensory and motor innervation of the femoral nerve?

Answer 20

motor-anterior branch: sartorius
motor-posterior branch: quadriceps
sensory: anterior thigh

Question 21

This nerve is often injured in patients who undergo extensive pelvic surgery.

Answer 21

obturator nerve

Question 22

What is the sensory and motor innervation of the obturator nerve?

Answer 22

sensory: distal inner thigh and part of hip
motor: hip adductors

Question 23

The largest nerve in the body is the

Answer 23

sciatic nerve

Question 24

What is the sensory and motor innervation of the sciatic nerve?

Answer 24

Motor: posterior thigh and lower leg
sensory: lower leg & foot

Question 25

The ______ nerve supplies sensory innervation to the posterior aspect of the thigh.

Answer 25

Posterior femoral cutaneous nerve

Question 26

The psoas compartment block anesthetizes all of the following nerves EXCEPT the:
a. saphenous
b. sciatic
c. obturator
d. lateral femoral cutaneous

Answer 26

B.

Question 27

The psoas compartment block is also known as the

Answer 27

lumbar plexus block

Question 28

The psoas compartment blocks targets the three major nerves of the lumbar plexus including the

Answer 28

femoral
obturator
and lateral femoral cutaneous nerves

Question 29

The psoas compartment block is useful when

Answer 29

neuraxial anesthesia is contraindicated and/or anesthesia to one lower extremity is preferred

Question 30

Local anesthetic volumes greater than 20 mLs for the psoas compartment block increase the risk of

Answer 30

bilateral spread and contralateral limb involvement
creating a bilateral sympathectomy

Question 31

_____ is a contraindication to the psoas block

Answer 31

Coagulopathy b/c of high complication rates of retroperitoneal hematoma and renal capsular injection

Question 32

The adductor canal block may be used because

Answer 32

it is a sensory block and prevents quadricep weakness

Question 33

What is the three in one block?

Answer 33

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

Question 34

Describe the dosage for continuous femoral nerve blocks.

Answer 34

8-10 mL/hr for up to 48 hours with 0.2% ropivacaine or 0.25% bupivacaine

Question 35

The femoral triangle is composed of

Answer 35

inguinal ligament
sartorious muscle
adductor longus muscle

Question 36

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

Answer 36

A & C

Question 37

The fascia iliaca block can be considered for

Answer 37

hip surgery; as well as femur and knee surgery and hip fractures

Question 38

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

Answer 38

B. saphenous

Question 39

The sciatic nerve provides motor innervation to the:
a. semitendinosus
b. sartorius
c. biceps femoris
d. quadriceps

Answer 39

A & C

Question 40

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

Answer 40

a. plantar flexion and inversion of the foot

Question 41

What are the five nerves of the ankle?

Answer 41

Sural nerve
tibial nerve
superficial peroneal nerve
deep peroneal nerve
saphenous nerve

Question 42

Which nerves of the ankle are purely sensory?

Answer 42

sural, superficial, and saphenous (easy to remember b/c they are the only ones that begin with a ‘s’)

Question 43

What is the elicited motor response of the tibial nerve?

Answer 43

inversion + plantar flexion

Question 44

What is the elicited motor response of the deep peroneal nerve?

Answer 44

eversion + dorsiflexion

Question 45

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

Answer 45

b. saphenous nerve