Lower Extremity Anatomy and Blocks Flashcards by Tricia Vantino

What nerve roots form the femoral nerve

L2-L4

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What nerve roots form the lateral femoral cutaneous nerve

L2-L3

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What nerve roots form the posterior femoral cutaneous nerve

S1-S3

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What nerve roots form the sciatic nerve

L4-S3

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What two plexi is innovate the lower extremity

Lumbar plexus and sacral plexus

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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

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Where does the sacral plexus originate from? What does it primarily innervate?

Anterior Rami of L4-S3
Primarily innervates the back of the leg

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What nerve roots form the obturator nerve

L2-L4

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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

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The sciatic nerve divides into two branches at the proximal popliteal fossa. What are those two branches?

Tibial Nerve and Common Peroneal (Fibular) Nerve

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The Tibial Nerve divides and gives rise to which 2 terminal branches?

Posterior Tibial Nerve and Sural Nerve

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The Common Peroneal Nerves arises from?

The sciatic nerve, roots L4-S2.

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The Common Peroneal Nerve divides and gives rise to which 3 terminal branches?

Deep peroneal nerve
Superficial peroneal nerve
Sural nerve

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The coccygeal plexus [S4, S5 and Coccygeal 1] give rise to what three nerves?

Pudendal
Inferior anal
Perineal

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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)

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What nerve provides cutaneous innervation to letter A

Lateral Femoral Cutaneous

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What nerve provides cutaneous innervation to letter B

Obturator

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What nerve provides cutaneous innervation to letter C

Saphenous N

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What nerve provides cutaneous innervation to letter D

Superficial peroneal

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What dermatome is associated with this sensory region: Medial thigh (upper)

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What dermatome is associated with this sensory region: Medial thigh (lower)

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What dermatome is associated with this sensory region: lateral thigh + anterior knee

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What dermatome is associated with this sensory region: lateral lower leg + top of foot

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What dermatome is associated with this sensory region: posterior leg (more lateral)

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What dermatome is associated with this sensory region: posterior leg (more medial)

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