Complex sentence: The main deep neurovascular bundle at risk is the posterior tibial, as it lies on the posterior aspect of the tibialis posterior and flexor digitorum longus muscles, and medial to the belly of flexor hallucis longus.
Split into simpler sentences: The main deep neurovascular bundle at risk is the posterior tibial. It lies on the posterior aspect of the tibialis posterior and flexor digitorum longus muscles, and medial to the belly of flexor hallucis longus.