Popliteal Sciatic Nerve Block
Highlights
- the sciatic nerve andits two branches are covered by a toughmembranous sheath that provides amechanism for the nerve to glide backand forth as the knee and hip jointsflex and extend this has been called theperineural sheath or in some circles thecircumneral sheath note (View Highlight)
- it's important to understandthat the sheath is not part of the nerve
like epineurium (View Highlight)
- placing aneedle within the sheath but outside thetwo nerves themselves say heredoes not represent an intraneuralinjection (View Highlight)
- the paraneural sheath is adiffusion barrier meaning that unlikethe brachial plexus sheath local doesn'ttravel all that well across it if yourlocal anesthetic is not within thesheath you're going to experience a slowonset and a weak block (View Highlight)
- the lateral poplitealsciatic block is one of the higher risk
peripheral blocks we do from theperspective of nerve injury this may bebecause the common peroneal nerve is notseen and accidentally contacted as aneedle is advanced (View Highlight)
- the commonperoneal nerve typically comprises twoto three large fascicles rather than adozen or more smaller ones which maypredispose it to mechanical injury dueto the relative lack of epineurialcushioning (View Highlight)