Femoral Block Flashcards
Where is the femoral nerve positioned in the femoral
canal?
The femoral nerve maintains a lateral position in the femoral
canal. In order from lateral to medial the structures are
remembered by the acronym NAVEL (nerve, artery, vein, empty
space, and lymphatics).
Butterworth JF, Mackey DC, Wasnick JD. Morgan & Mikhail’s
Clinical Anesthesiology. 5th ed. New York, NY: McGraw-Hill;
2013: 1003.
Where is the femoral nerve positioned at the level of
the inguinal crease?
At the inguinal crease (perhaps the easiest place to locate it), it
is found avout 0.5 cm lateral to the femoral artery.
Barash PG, Cullen BF, Stoelting RK, Cahalan MK, Stock MC,
Ortega R. Clinical Anesthesia. 7th ed. Philadelphia, PA:
Lippincott Williams and Wilkins; 2013: 1634.
What muscles receive innervation from the femoral
nerve?
The posterior branches of the femoral nerve provide motor input
to the quadriceps.
Longnecker DE, Newman MF, Brown DL, Zapol WM.
Anesthesiology. 2nd ed. New York: McGraw-Hill; 2012: 840.
What area receives sensory innervation from the
femoral nerve?
The skin of the anterior thigh from the inguinal ligament to the
knee. The terminal branch of the femoral nerve (the saphenous
nerve) supplies the medial side of the leg from the knee to the
great toe.
Butterworth JF, Mackey DC, Wasnick JD. Morgan & Mikhail’s
Clinical Anesthesiology. 5th ed. New York, NY: McGraw-Hill;
2013: 1002.
What nerve roots contribute to the femoral nerve?
L2, L3, L4
Longnecker DE, Newman MF, Brown DL, Zapol WM.
Anesthesiology. 2nd ed. New York: McGraw-Hill; 2012: 840.
Is a femoral nerve block adequate as the sole
anesthetic for an anterior cruciate ligament repair
with a hamstring autograft? Why or why not?
No, because the area incised for the hamstring autograft is
innervated by the sciatic nerve. A combination of femoral nerve
block and sciatic block will be required for this procedure.
Barash PG, Cullen BF, Stoelting RK, Cahalan MK, Stock MC,
Ortega R. Clinical Anesthesia. 7th ed. Philadelphia, PA:
Lippincott Williams and Wilkins; 2013: 1634.
How is correct needle placement identified for a
femoral nerve block when using a nerve stimulator?
Correct needle placement is confirmed when stimulation of the
quadriceps and sartorius muscles is seen. (This often causes a
‘patellar snap’ or upward motion of the patella when the nerve
stimulator is set at 0.3-0.5 mA.)
Barash PG, Cullen BF, Stoelting RK, Cahalan MK, Stock MC,
Ortega R. Clinical Anesthesia. 7th ed. Philadelphia, PA:
Lippincott Williams and Wilkins; 2013: 1634.
How would you block the lateral femoral cutaneous
nerve?
The lateral femoral cutaneous nerve emerges underneath the
inguinal ligament and becomes superficial inside the fascia lata
near the anterior superior iliac spine. It can be anesthetized by
inserting a needle 2 cm medial and caudal to the anterior
superior iliac spine and injecting 10-15 mL of local anesthetic
after the needle penetrates the fascia lata.
Butterworth JF, Mackey DC, Wasnick JD. Morgan & Mikhail’s
Clinical Anesthesiology. 5th ed. New York, NY: McGraw-Hill;
2013: 1004-1006.
You have performed a three-in-one block on a
patient for postoperative pain control. The patient is
concerned because he is unable to adduct the
affected leg after the performing the block. What is
the cause of his inability to adduct the leg?
The obturator nerve provides sensation to the medial aspect of
the thigh and motor innervation to the adductor muscles located
in the medial thigh. This nerve is anesthetized during a three-inone
block.
Butterworth JF, Mackey DC, Wasnick JD. Morgan & Mikhail’s
Clinical Anesthesiology. 5th ed. New York, NY: McGraw-Hill;
2013: 1001.
What is a ‘three-in-one” block?
A “three-in-one” block anesthetizes the lateral femoral
cutaneous, obturator, and femoral nerves and is performed by
injecting 20-40 mL of local anesthetic into the neurovascular
sheath just lateral to the femoral pulse. The term “three-in-one
block” has almost been abandoned in recent years because of
the high rate of failure to block all three nerves with a single
injection.
Butterworth JF, Mackey DC, Wasnick JD. Morgan & Mikhail’s
Clinical Anesthesiology. 5th ed. New York, NY: McGraw-Hill;
2013: 1002.
For what procedures is a femoral nerve block useful?
It provides adequate anesthesia for surgeries limited to the
anterior thigh, such as muscle biopsies, and has been reported
useful for knee arthroscopy and repair of midfemoral fractures.
Longnecker DE, Newman MF, Brown DL, Zapol WM.
Anesthesiology. 2nd ed. New York: McGraw-Hill; 2012: 840.
