It is also possible to move the probe proximal to the bifurcation of the sciatic nerve and block the nerve guided by ultrasound at this level

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The sciatic nerve branches (the tibial nerve and the common peroneal nerve) innervate the entire leg, ankle and foot

The only exception is the saphenous nerve territory and a strip of skin distal to the popliteal fossa which is innervated by the posterior femoral cutaneous nerve

The posterior cutaneous nerve of thigh (also known as the posterior femoral cutaneous nerve) is a branch of the sacral nerve plexus and leaves the pelvic cavity through the greater sciatic foramen

It supplies a vertical strip of skin extending from the distal gluteal region down to mid-calf level

– Locate the pulsating popliteal artery at the level of the popliteal crease

– Look for the tibial nerve between the artery and the skin

– Look for the common peroneal nerve lateral to the tibial nerve

– Track the tibial nerve and the common peroneal nerve proximally until they unite and become the sciatic nerve

– Place the patient in the lateral position and the probe in the popliteal crease

– Visualise the tibial nerve between the popliteal artery and the probe

– Track the tibial nerve proximally until it unites with the peroneal nerve and the two become the sciatic nerve

– Insert the needle from the lateral end of the probe and advance the needle in-plane until the tip of the needle touches the peroneal nerve tangentially

– Inject the local anesthetic

– Relocate the tip of the needle until you obtain complete perineural spread of local anaesthetic around both the peroneal and the tibial nerve

The common peroneal nerve (P) typically presents as one single round anehoic (black) profile just before it branches off from the sciatic nerve (S)

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It is easy and requires only a small volume of local anaesthetic to anaesthetise the two branches of the sciatic nerve – the tibial nerve and the common peroneal nerve – individually

The two sciatic branches are easy to access as they are more superficially located than the sciatic nerve before the bifurcation

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The lateral cutaneous nerve of calf (also known as the lateral sural nerve) is a cutaneous branch of the common fibular nerve

It arises near the neck of the fibula and supplies skin over the lateral aspect of the leg just distal to the knee

The superficial fibular nerve is the smallest of the two terminal branches of the common fibular nerve

It innervates the muscles of the lateral compartment of the leg

It supplies cutaneous branches to the lateral aspect of the distal half of leg

The branches of the superficial peroneal nerve supply the dorsum of the foot and the toes

The deep peroneal nerve is the biggest of the two terminal branches of the common peroneal nerve

The deep peroneal nerve descends within the anterior crural compartment and supplies all the muscles of this compartment

It crosses in front of the ankle joint, giving an articular branch to the ankle joint, before the terminal branches innervate the dorsum of the foot, lateral to the dorsalis pedis artery

It innervates the skin of the interspace between the 1st and 2nd toes

It also innervates the digital extensor muscles and some of the tarsal and tarsometatarsal joints