Most lateral structure in flexor retinaculum of leg is

FLEXOR RETINACULUM (LEG):- Attachments:Anteriorly-posterior border and tip of medial malleolus.Posteriorly and laterally-medial tubercle of calcaneum. Septa passing from the retinaculum to the underlying bone divide the space deep to retinaculum into four compaments. Structures passing deep to this:(Medial to lateral)1. Tendon of Tibialis posterior.2. Tendon of flexor digitorum longus 3. Posterior tibial aery and its terminal branches along with accompanying veins.4. Tibial nerve and its terminal branches.5. Tendon of flexor hallucis longus. Each tendon separate compament.Aery and nerve same compament.Near the calcaneum, it is pierced by the medial calcaneal vessels and nerves.Lower pa of deep surface of retinaculum gives origin to greater pa of abductor hallucis muscle. Tibial nerve injury under flexor retinaculum-Tarsal tunnel syndrome. {Reference: BDC 6E pg no.105}