Episode 138: Lower Extremity Blocks Part 1: Ankle and Sciatic

In this 138th episode I welcome Drs. Segna and Rayaz back to the show to discuss lower extremity nerve blocks. We cover the ankle block and sciatic nerve block approaches today and will cover the anterior leg in a later episode.

The Medium Article: https://medium.com/@admiralcloudberg/the-near-crash-of-air-canada-flight-759-c61094867d45

4 Replies to “Episode 138: Lower Extremity Blocks Part 1: Ankle and Sciatic”

  1. Do you have a consensus list of what is considered a “deep” vs “superficial” peripheral nerve block? It seems to be somewhat provider dependent (ex: many providers consider Axillary to be the only “superficial” brachial plexus block). Thanks!

    1. Hi Zach,

      Per Dr. Segna:
      It is provider and patient dependent but here is a generalized list that most people go by:
      Superficial: interscalene, supraclavicular, axillary, PEC, serratus, TAP, QL, femoral, fascia iliaca, popliteal, ankle
      Deep: infraclavicular, sciatic (depending on how high), erector spinae, paravertebral

  2. Thank you for these wonderful podcasts that are super high yield! Regarding the question “which nerve would need to be stimulated to produce toe extension”, the answer was said to be superficial peroneal; however, I believe it is deep peroneal bc the superficial peroneal everts the foot while deep peroneal causes dorsiflexion and extension of the toes. This brings about another point regarding the mnemonic for sensory vs motor – superficial peroneal appears to also be both sensory and motor.

    1. Thanks Cindy. Here is Dr. Segna’s response:

      The board exams are trying to cover things very broadly. The deep peroneal nerve has both motor and sensory components. The motor component is responsible for innervating the anterior compartment of the lower leg which includes the tibialis anterior, extensor hallucis longus, extensor digitorum longus, and peroneus tertius muscles. Activation of these muscles by the deep peroneal nerve is primarily responsible for dorsiflexion of the foot, the extension of the toes, and assists the dominating tibialis anterior with inversion of the foot. We definitely did not say the correct answer here so it was a poor question choice from us. Most commonly the deep peroneal nerve is tested as the sensory portion between the large and first toe webspace.

      The superficial peroneal nerve gives motor innervation to the peroneus longus and brevis muscles and sensory branches that carry sensory information from the anterolateral aspect of the leg and the greater part of the dorsum of the foot (except for the first web space).

      The open anesthesia pneumonic was a generalization to help trainees try and keep these nerves straight. We thought that it may have been helpful given the large breadth of information one needs to manage for the board exam.

      https://www.ncbi.nlm.nih.gov/books/NBK526033/
      https://www.ncbi.nlm.nih.gov/books/NBK537363/

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