Lower body blocks (exam 2) Flashcards
Analgesia refers to?
pain relief
Anesthesia refers to?
allows you to perform surgery (loss of consciousness with GA) but loss of consciousness is not necassary.
The lumbar plexus supplies motor and sensory innervation to??
anterior portion and cutaneous sensory medial lower leg (saphenous nerve).
Lumbar plexus arises from what roots?
L1-L4
**3 major nerves make up the Lumbar plexus, what are they?
Lateral Femoral Cutaneous L2-L3 (M&M says L1-3)
Obturator L2-L4 (Freq. injured in pelvic surg)
Femoral L2-L4 (largest branch of LP)
Sacral Plexus is derived from what rami?
anterior rami of the L4 and L5 and S1-S4 nerves.
What three nerves are included in the Sacral plexus block?
Sciatic L4-S3 (largest nerve trunk in the body)
Posterior cutaneous nerve (S1-3)
Terminal branches-tibial and common peroneal
4 major nerves that supply all of the lower extremity?
Lateral femoral cutaneous nerve
Femoral nerve (anterior crural nerve)
Obturator nerve
Sciatic nerve
(Posterior cutaneous nerve of thigh (S1-S3)
Does the Lumbar Plexus Block supply complete anesthesia of the lower extremity?
Does not supply complete anesthesia of lower extremity because it cannot achieve blockade of the sacral roots that supply the sciatic nerve
Posterior Lumbar Plexus block:
position?
landmark?
Position: Lateral
Landmarks: 4cm lateral to L4 Spinous processes
Technique for Posterior Lumbar Plexus block?
A line is drawn through the lumbar spinous processes and then a line is drawn through iliac crests (at level of L4)
Palpate superior iliac spine and draw another line cephalad (parallel to spinous process line).. (Point of entry will be b/w these 2 parallel lines)
What does the femeral nerve innervate?
Innervates main hip flexors, knee extensions & provides much of the sensory innervation of the hip & thigh
What is a 3-in-1 block
The term 3-in-1 block refers to anesthetizing the femoral, lateral femoral cutaneous, and obturator nerves with a single injection below the inguinal ligament (not always successful- it is difficult to get all 3 nerves with one single injection)
Femoral nerve block alone will not provide surgical analgesia for ? (what 3-4 parts of the leg)
hip, thigh, knee, and/or ankle
Femoral nerve block, does it have high risk or low risk of complications?
relative low risk?
Femoral nerve block Technique? What do you want to see elicited with the PNS?
Palpate femoral artery at level of inguinal ligament (may use US to view structures- femoral vein, artery & femoral nerve- a spindle shaped structure with a “honey comb” texture)
quadriceps twitch should be elicited with PNS
Regarded as a femoral nerve block only?
Femoral 3-in-1 block
With a femoral 3-in-1 block where does it produce anesthesia?
anterior portion of the upper leg and medial calf and results in inability to abduct the leg or extend the lower leg.
Anesthesia- what would a definition be?
procedure can occur (they are not asleep) and post operative you have pain relief.
lateral femoral cutaneous nerve block is typically used as a supplement to what nerve block?
femoral nerve block
Indications for the use of a lateral femoral cutaneous nerve block?
Used in conjunction with blockade of other nerves to provide anesthesia for surgical procedures involving the leg.
Alone, it is used to provide anesthesia for superficial procedures on the lateral thigh, such as skin grafting.
It is also used in the diagnosis and treatment of meralgia paresthetica, a pain syndrome involving the lateral femoral cutaneous nerve.
femoral cutaneous nerve block, what structure do you pass through that creates a pop??
The fascia lata is identified by a “release” or a “pop” as a needle passes through it.
What nerve block in practice has no side effects or complications?
Lateral femoral cutaneous nerve block!
Obturator nerve, is it sensory or motor nerve?
Both a motor and a sensory nerve
Sensory branches to the hip & knee joints, medial thigh
Innervates the adductors of the hip
When is the obturator nerve usually blocked? (in conjunction with)
The obturator nerve is usually blocked in conjunction with the lateral femoral cutaneous, femoral, and sciatic nerves for surgical procedures on the leg.
When is a block of the obturator nerve alone used?
The block used alone is useful in aiding in the diagnosis and treatment of pain syndromes involving the hip joint, as well as relieving adductor spasms of the hip.
What nerve stimulation do you want to see if using an obturator nerve block?
thigh adduction
What do you need to pay careful attention to with an obturator nerve block?
Careful attention to the bony landmarks and the depth of needle insertion reduces the chance of needle placement into surrounding structures such as the bladder, rectum, vagina, or spermatic cord.
Sciatic nerve block is mostly indicated for?
procedures involving the hip, thigh, knee, lower leg & foot
you can combine a sciatic nerve block with what other nerve block to provide complete anesthesia and post-op analgesia for lower extremity surgery? (2)
lumbar plexus block or femoral 3-in-1 block.
What muscle twitch do you want to elicit with a Sciatic block?
plantar or dorsiflexion is elicited (plantar flexion- distal ankle, foot or toes… or foot inversion)
Side effect of sciatic nerve block can be what two things?
Mild hypotension due to sympathetic fibers being blocked
Residual dysesthesias (abnormal sensation) usually improving 1-3 days
Sciatic nerve divides into what two other nerves?
tibial and common peroneal nerve
What do you want to avoid with an ankle block?
Avoid excessive LA volume and avoid epinephrine (to avoid risk of ischemic complications)
Ankle block typically requires how many injections?
5 seperate injections
Posterior tibial nerve- direct continuation of tibial
Deep peroneal nerve- runs off common peroneal
Superficial peroneal nerve- runs off common peroneal
Sural nerve- branch of tibial
Saphenous nerve (terminal branch of femoral)- not a part of sciatic system
