Fig. 4

Anatomical, ultrasound and clinical images of ankle block procedures, which involve anaesthetising five separate nerves: two deep (posterior tibial and deep peroneal) and three superficial nerves (superficial peroneal, sural and saphenous). (1) Deep Peroneal Nerve: it innervates the ankle extensor muscles, the ankle joint and the web space between the first and second toes. A transducer placed in the transverse orientation at the level of the extensor retinaculum will show this nerve (DPN) lying immediately lateral to the anterior tibial artery (ATA) on the surface of the tibia. (2) Superficial Peroneal Nerve: it innervates the dorsum of the foot and emerges to lie superficial to the fascia, 10–20 cm above the ankle joint on the anterolateral surface of the leg, and divides into two or three small branches. A transducer placed transversely on the leg, approximately 5–10 cm proximal and anterior to the lateral malleolus, will identify the hyperechoic nerve branches (SPN) lying in the subcutaneous tissue immediately superficial to the fascia. (3) Sural Nerve: it innervates the lateral margin of the foot and ankle. This nerve (SUN) can be traced back along the posterior aspect of the leg, running in the midline superficial to the Achilles tendon and gastrocnemius muscles, in the immediate vicinity of the small saphenous vein (V). (4) Posterior tibial nerve: it provides innervation to the heel and sole of the foot. This nerve (N) can be seen posterior to the posterior tibial artery (PTA) and vein (PTV) using a linear transducer placed transversely at the level of the medial malleolus. The nerve typically appears hyperechoic with a honeycomb pattern. (5) Saphenous nerve: it innervates the medial malleolus and a variable portion of the medial aspect of the leg below the knee. This nerve (SAN) travels down the medial leg alongside the great saphenous vein (SV). Because it is a small nerve, it is best visualised 10–15 cm proximal to the medial malleolus using the great saphenous vein as a landmark