Crural Fascia

fascia cruris

The crural fascia is the deep investing fascia of the lower leg, encircling all compartments and attaching to the anterior tibial crest medially and the fibula laterally. It continues below as the extensor and flexor retinacula at the ankle and is continuous with the iliotibial band and patellar retinaculum above.

Anatomical Data

Boundaries & Contents

Location	Deep fascia surrounding the whole leg between the knee and the ankle
Boundaries	Blends with the periosteum of the subcutaneous (anteromedial) surface of the tibia Above: continuous with the fascia lata and attached around the knee to the patella, tibial tuberosity, tibial condyles and fibular head Below: thickened as the superior and inferior extensor, flexor and fibular retinacula Sends anterior and posterior intermuscular septa to the fibula and the transverse septum across the back of the leg
Contents	Muscles, vessels and nerves of the anterior, lateral, superficial posterior and deep posterior compartments

Biomechanics

Function & Actions

Encloses the leg muscles in tight compartments, which improves the calf pump for venous return but also allows pressure to build in compartment syndrome.

Clinical Relevance

Clinical Notes

The crural fascia is released in all approaches to lower leg fasciotomy. Fascial herniation through defects in the crural fascia is a common cause of lateral leg pain in runners, where the superficial peroneal nerve may be entrapped at the fascial exit point. The fascia is harvested as an autograft for tendon reconstruction.

Pathology

Common Injuries & Conditions

Fascial Herniation with Nerve Entrapment

Superficial peroneal nerve entrapment at a defect in the crural fascia producing activity-related lateral leg pain and dorsal foot numbness, treated by surgical fascial release at the herniation point.

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