A common epineural sheath for the nerves in the popliteal fossa and its possible implications for sciatic nerve block

A Randomized Comparison Between Subepineural and Conventional Ultrasound-Guided Popliteal Sciatic Nerve Block

“…In this location, both branches can still be found inside a common epineural sheath. 4,5 An initial skin wheal was raised with 3 mL of lidocaine 1%. Using an out-of-plane technique, a 17-gauge, 8.9-cm Tuohy needle was advanced until its tip was positioned between the tibial and peroneal nerves.…”

Lower Extremity Reconstruction under Popliteal Sciatic Nerve (Tibioperoneal Trunk) and Saphenous Nerve Block

“…Despite the variation of the nerve bifurcation and distribution, it is a well-known fact that a common epineural sheath encases both tibial and common peroneal nerves continuously up to the sciatic nerve. 15,16 A single injection in the common sheath will spread to the tibial and common peroneal nerves. The upper one-third of the popliteal fossa triangle is usually above 8 to 9 cm from the popliteal crease.…”

“…This will increase the probability of needle placement within the vicinity of or proximal to the division of the sciatic nerve. 15,16 In the early stage of our trial, because of our inexperience, a nerve stimulator was used to correctly identify needle placement. However, after a few trials, the surface anatomical landmarks and the sensation of penetrating the popliteal fossa were constant and sufficient to obtain a successful block without the nerve stimulator.…”

Revisiting Anatomic Landmarks

“…10,11,17 The commonly suggested insertion point for the block, 5 to 7 cm proximal to the popliteal crease, 2Y5 is believed to be at or proximal to the level of SN bifurcation. If the SN bifurcates proximal to this level, however, a single injection would most likely fail to block both branches of the SN, resulting in failure or partial failure of the block.…”