Ankle blocks Flashcards
The cutaneous branch of the femoral nerve that is blocked in an ankle block?
saphenous
Ankle block requires how many needle insertions?
5
Onset time for ankle block?
10-25 minutes
What develops faster in ankle block-motor or sensory anesthesia?
sensory
Ankle block volume?
5-6 mL
Can you use epi in ankle blocks?
never
With the exception of the saphenous nerve, an ankle block is a block of which branches of the sciatic nerve?
terminal
What are the 2 deep nerves and 3 superficial nerves blocked in ankle block?
2 deep: posterior tibial, deep peroneal; superficial: saphenous, sural, superficial peroneal nerves
How are the 2 deep nerves anesthetized?
injecting LA underneath superficial fassa
How are the 3 superficial nerves anesthetized?
injecting LA SQ
Largest nerve in body?
sciatic (2 cm in breadth at take off)
Sciatic nerve is formed starting where on the spine to what part of spine?
L4-S3 roots
Where does the sciatic nerve exit the pelvis?
greater sciatic foramen
The sciatic nerve descends between what 2 structures?
greater trochanter of the femur and tuberosity of ischium
The sciatic nerve splits in to what 2 branches at the lower 1/3 of the back of the thigh?
common peroneal, tibeal nerve
Largest branch of the lumbar plexus?
femoral branch
The femoral branch arises from which 3 lumbar nerves?
2nd, 3rd, 4th
Eventually the femoral nerve passes under which ligament?
inguinal
As the femoral nerve passes under the thigh and inguinal ligament, it flattens and how is it positioned?
laterally and slightly deeper than the femoral artery
Think of what pneumonic when going from medial to lateral and trying to recall the relationship of the femoral nerve to vessels in the femoral triangle?
LVAN (lymph, vein, artery, nerve)
This nerve is the origin of the deep peroneal nerve and superficial peroneal nerve?
common peroneal nerve
The common peroneal nerve separates from which nerve and descends along?
tibial nerve; tendons of biceps femoris muscle around neck of fibula
How can you find where the deep peroneal nerve is on the patient?
ask the pt to flex the foot back towards nose and there is a devit between anterior tibial and extensor digitorum longus muscle
The superficial peroneal nerve is a branch of which nerve?
common peroneal nerve
What is the size of the superficial peroneal nerve and what does that mean for anesthesia?
its tiny and easy to block
The superficial peroneal nerve divides in to which branches?
terminal cutaneous branches; medial and lateral dorsal cutaneous nerves
Where is the tibial nerve located/positioned between what?
positioned laterally and posteriorly to posterior tibial artery and midway between posterior aspect of medial malleolus and posterior aspect of achilles tendon
What type of nerve is the sural nerve?
sensory
This nerve supplies the medial malleolus, achilles tendon, and ankle joint
sural nerve
This nerve supplies innervation to skin, SQ tissue, 4th interossius space, and sensory innervation of 5th toe
sural nerve
This nerve is the terminal cutaneous branch of the femoral nerve?
saphenous nerve
Does an ankle block result in anesthesia of the ankle?
no
The proximal branches of which 2 nerves provide innervation to the deep structures of the ankle?
tibial and peroneal
Which nerve in the foot provides sensation to the web between the 1st and 2nd toes?
deep peroneal nerve
You should only use propofol for sedation for ankle block if?
you have an assistant
How do you position the foot for an ankle block?
supine with foot over footrest
Equipment needed for ankle block?
sterile towels, 4x4 gauze, CHG or betadine prep solution, 3 10 mL syringes with LA, sterile gloves, marking pen, one 1.5 inch 25 gauge needle
Is ultrasound helpful for an ankle block?
no
Deep peroneal nerve is located where?
immediately lateral to tendon of extensor hallucis langus
Deep peroneal nerve is located between which 2 structures?
extensor hallucis longus, extensor digitorum longus
The pulse of which artery can be felt at the landmark for deep peroneal nerve?
DP
The deep peroneal nerve is what position from the anterior tibial artery (DP)?
immediately lateral
Which nerves do you start with with Kathy’s technique in ankle block?
deep-deep peroneal and posterior tibial
How can you anesthetize the superficial nerves for an ankle block?
fanning out across a line that extends from the most cephalad point of the medial malleolus to the most cephalad point of the lateral malleolus
Tip for blocking the peroneal nerve?
put your index finger on the groove just lateral to the extensor hallus longus. advance needle to the bone and withdraw 1-2 mm and inject 2-3 mL in a direction that is perpendicular in all planes (redirect needle 30 degrees laterally and medially)
How do you inject the posterior tibial nerve?
inject LA just behind the medial malleolus and advanced until bone is felt; withdraw needle 1-2 mm and inject 2-3 mL of LA. 2 boluses given laterally and medially
How do you do a sural, saphenous, and superficial peroneal block?
start where extensor hallus longus is and inject in a superficial ring in the direction of the line that you made from the top of the medial malleolus to the lateral malleolus
4 complications of ankle block?
infection, hematoma, vascular injection, nerve injury
What can you do to prevent vascular injection?
aspirate
How can you prevent nerve injury while doing ankle block?
stop if pt reports excruciating pain or if encounter high pressures
Most commonly failed block?
ankle block
Most common indication for ankle nerve block?
diabetic ankle surgery
Ankle block is not suited for which type of surgery?
ankle
Most of dorsal part of foot gets innervation from?
superficial peroneal nerve
Medial aspect of foot receives sensory innervation from?
saphenous nerve
Lateral aspect of foot is supplied by?
sural nerve; originates from tibeal nerve in popliteal fossa behind knee
Medial and posterior aspect of heel supplied by?
medial branch of tibial nerve
Does LA cross fascia readily?
no
This nerve supplies approx complete sole of foot?
tibial
Main blood supply to foot?
posterior tibial artery, dorsal pedal artery
Post tibial artery and dorsal pedal artery are close to which nerves?
tibial nerve and deep peroneal nerve
If PT cannot be palpated what is the landmark?
halfway between medial malleolus and achilles tendon
What action when using nerve monitoring to block tibial and deep peroneal nerve indicates that the nerve has been encountered?
toe flexion
When using nerve monitor in diabetic patients with neuropathy, what may you have to do to the ampules?
increase
The motor response, when using nerve monitoring, immediately ceases upon?
injection of LA
