Lower Extremity Anatomy and Blocks Flashcards
What nerve roots form the femoral nerve
L2-L4
What nerve roots form the lateral femoral cutaneous nerve
L2-L3
What nerve roots form the posterior femoral cutaneous nerve
S1-S3
What nerve roots form the sciatic nerve
L4-S3
What two plexi is innovate the lower extremity
Lumbar plexus and sacral plexus
Where does the lumbar plexus originate from? What does it primarily innervate?
Anterior Rami of L1-L4 (+T12 in 50% of population)
Primarily innervates the front of the leg
Where does the sacral plexus originate from? What does it primarily innervate?
Anterior Rami of L4-S3
Primarily innervates the back of the leg
What nerve roots form the obturator nerve
L2-L4
What nerve is the largest nerve in the body and is the most important branch of the sacral plexus in regional anesthesia of the lower extremity?
Sciatic Nerve
The sciatic nerve divides into two branches at the proximal popliteal fossa. What are those two branches?
Tibial Nerve and Common Peroneal (Fibular) Nerve
The Tibial Nerve divides and gives rise to which 2 terminal branches?
Posterior Tibial Nerve and Sural Nerve
The Common Peroneal Nerves arises from?
The sciatic nerve, roots L4-S2.
The Common Peroneal Nerve divides and gives rise to which 3 terminal branches?
Deep peroneal nerve
Superficial peroneal nerve
Sural nerve
The coccygeal plexus [S4, S5 and Coccygeal 1] give rise to what three nerves?
Pudendal
Inferior anal
Perineal
The foot and ankle are innervated by what 5 nerves?
Saphenous N (originates from femoral n.)
Sural N
Superficial Peroneal N
Deep Peroneal N
Posterior Tibial N
(the other 4 originate from sciatic n)
What nerve provides cutaneous innervation to letter A
Lateral Femoral Cutaneous
What nerve provides cutaneous innervation to letter B
Obturator
What nerve provides cutaneous innervation to letter C
Saphenous N
What nerve provides cutaneous innervation to letter D
Superficial peroneal
What dermatome is associated with this sensory region: Medial thigh (upper)
L2
What dermatome is associated with this sensory region: Medial thigh (lower)
L3
What dermatome is associated with this sensory region: lateral thigh + anterior knee
L4
What dermatome is associated with this sensory region: lateral lower leg + top of foot
L5
What dermatome is associated with this sensory region: posterior leg (more lateral)
S1
What dermatome is associated with this sensory region: posterior leg (more medial)
S2
What lower extremity peripheral nerves are sensory only
Lateral femoral cutaneous
saphenous
sural
What lower extremity peripheral nerves are combined sensory-motor?
Femoral
Obturator
Posterior Tibial
Deep Peroneal
Superficial Peroneal
Which plexus, Lumbar or Sacral, innervates the red regions
Lumbar Plexus
Which plexus, Lumbar or Sacral, innervates the blue regions
Sacral Plexus
What nerve innervates the sensory region: the lateral thigh to the knee, (lime green)
Lateral femoral cutaneous
What nerve innervates the sensory region: the anterior thigh and medial aspect of lower leg, (maroon and light blue)
Femoral Nerve - anterior branch - maroon
Femoral Nerve - posterior branch aka Saphenous N (branch from Femoral N)
What nerve innervates the sensory region: the posterior hip to upper/mid calf, (lavender)
Posterior femoral cutaneous N
What nerve innervates the sensory region: medial thigh (and articular branch of he hip joint), (yellow)
Obturator N
What nerve innervates the sensory region: (light orange)
Common Peroneal N
What nerve innervates the sensory region: Dorsal surface of foot, anterior mid to lateral calf (pink)
Superficial Peroneal Nerve
What nerve innervates the sensory region: Web space between big toe and 2nd toe (dark blue)
Deep Peroneal Nerve
What nerve innervates the sensory region: lateral aspect of food-dorsal pinky toe and lateral ankle (dark purple)
Sural N
What nerve innervates the sensory region: Heel (red)
Tibial (medial calcaneal)
What nerve innervates the sensory region: planter surface of pinky (dark green)
Tibial - lateral plantar
What nerve innervates the sensory region: plantar surface of the foot (beige)
tibial nerve. medial plantar
Motor fxns of the femoral nerve for the hip and knee
hip: flexion and lateral rotation
knee: extension and flexion (minor contribution by satorius muscle)
Motor fxns of the obturator nerve for the hip
hip: adduction + flexion + extension
What are the three landmarks that make up the borders of the femoral triangle? Mnemonic is SAIL
Sartorius muscle
Adductor longus muscle
Inguinal ligament
From medial to lateral what are the three anatomic structures inside the femoral triangle? Mnemonic is VAN
Femoral Vein, artery, nerve
Where does the femoral nerve divide into anterior and posterior branches? What are the branches and what areas do they innervate?
Once under the inguinal ligament.
-The anterior branch innervates, the ventral surface of the thigh in Sartorius muscle
-The posterior branch innervates, the quadriceps muscles knee joint and it’s medial ligament.
When used alone, the femoral nerve block does or does not provides sufficient coverage for surgical anesthesia.
DOES NOT provide. But when included with a sciatic nerve block, provides coverage for the lower extremity
When combined with a ______ nerve block, a femoral nerve block provides almost complete surgical coverage to the lower extremity
sciatic
Where is the femoral nerve most compact?
Just distal to the inguinal ligament
What are some indications for femoral nerve block?
Provide surgical anesthesia and analgesia for procedures involving the femur, quadriceps, and knee(TKA)
Offers reliable, acute pain management for hip fractures
Complications of a femoral nerve block include:
Failed or incomplete block
Falls due to quadriceps weakness
Inadvertent vascular puncture and nerve injury
Regardless of technique, landmark or ultrasound, guidance, in a femoral nerve block. The needle tip must penetrate what two structures to ensure an efficacious block.
Fascia lata and fascia iliaca
What lower extremity peripheral nerve block does the image represent?
Femoral nerve block
What is the advantage of performing an adductor canal block over a femoral nerve block as part of a multimodal pain management plan?
Limits quadriceps weakness
The adductor canal originates at?
The apex of the femoral triangle
Indications for an Adductor Canal Block
ACL repair
MCL repair
Patella fracture
Vein stripping and harvesting
Supplementation to a sciatic nerve block for foot/ankle surgery
What lower extremity nerve block is represented in the diagram
Adductor Canal Block
What are three complications that can occur following a Adductor canal block?
-Quadriceps weakness - more likely with proximal injections and local anesthetic volumes greater than 20 ML
-Myotoxicity for local anesthetic injection inside the muscle
-Uncommon, vascular puncture, and nerve injury.
Between what two muscles are you injecting your local anesthetic for a Adductor canal block?
into the fascial plane between the Vastus Medialis and Sartorius Muscles
Stimulation of the tibial nerve in the popliteal fossa causes:
Plantar flexion and inversion of the foot
Approximately 7 to 10 cm proximal to the popliteal fossa, the _________ nerve becomes superficial and divides into the ______ nerve and _______ nerve.
Sciatic nerve
Tibial nerve and common peroneal nerve
The popliteal nerve block targets?
The sciatic nerve branches in the proximal popliteal fossa
Indications for a popliteal nerve block
Provides pain control for below the knee surgical procedures, such as ankle surgeries, Achilles tendon repair in foot surgeries. It also helps manage acute pain.
When combined with the _________ nerve block, the popliteal nerve block provides complete coverage of the lower extremity below the knee
Saphenous
Possible complications for a popliteal nerve block
-Although uncommon possible nerve injury, and inadvertent vascular puncture, resulting in hematoma or LAST events
-Falls d/t foot drop and numbness of the sole of foot
What nerve provides sensory innervation to these medial aspects of the ankle and foot?
Saphenous N (arises from the femoral N)
What nerve provides sensory innervation the posterior portion of the heel, lateral sole of the foot, and achilles tendon above the ankle?
Sural N.
What nerve, when it reaches the lower 1/3 of the leg, becomes sensory only, and innervates the dorsum of the foot?
Superficial Peroneal Nerve (a branch of the common peroneal)
What nerve provides sensory innervation to the sole of the foot and motor innervation to the foot - producing plantar flexion + inversion
Posterior Tibial Nerve
(in the foot divides into the medial calcaneal, lateral plantar, and medial plantar nerves)
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 which nerve?
saphenous nerve
What nerve provides sensory innervation to #1 in the photo
Sural Nerve
What nerve provides sensory innervation to the #2 in the photo
Saphenous Nerve
What nerve provides sensory innervation to #3 in the photo
Deep Peroneal Nerve
What nerve provides sensory innervation to #4 in the photo
Superficial Peroneal Nerve
What nerve provides sensory innervation to #5 in the photo
Plantar Nerve (posterior tibial branch)
What nerve provides sensory innervation to #6 in the photo
Calcaneal Nerve (Posterior Tibial Branch)
of the 5 nerves that innervate the ankle, which two are “Deep” Nerves Torabi Red Item
Tibial and Deep Peroneal Nerves
LAST is caused by?
High plasma concentrations of local anesthetic agent
MAX Dose of Bupivacaine without Epi
2mg/kg
175mg
MAX Dose of Lidocaine without epi
5mg/kg
350mg
MAX dose of Bupivacaine WITH epi
3mg/kg
225mg
MAX dose of Lidocaine WITH epi
7mg/kg
500mg
What is the % and mL amount of the standard Intralipid Treatment for LAST
20%
100mL
