Posterior Compartment of the Leg

compartimentum posterius superficiale cruris

The superficial posterior compartment contains gastrocnemius, soleus, and plantaris, enclosed by the crural fascia. The deep posterior compartment lies deep to the transverse intermuscular septum and contains tibialis posterior, flexor digitorum longus, flexor hallucis longus, the tibial nerve, and the posterior tibial artery. These are managed as separate compartments during fasciotomy.

Anatomical Data

Boundaries & Contents

Location	Back of the leg, the superficial posterior compartment forming the calf
Boundaries	Transverse intermuscular septum (deep) Deep (crural) fascia (superficial and sides)
Contents	Gastrocnemius Soleus Plantaris Branches of the tibial nerve and sural arteries supplying them

Biomechanics

Function & Actions

Holds the calf muscles that plantarflex the ankle and power walking, running and jumping. It is the largest compartment of the leg and less often affected by compartment syndrome than the anterior one.

Clinical Relevance

Clinical Notes

The deep posterior compartment is the most frequently missed in lower leg fasciotomy. Isolated deep posterior compartment syndrome produces medial calf pain with dorsiflexion of the toes and tenderness over the flexors. The two-incision fasciotomy technique (medial and lateral) reliably decompresses all four compartments. Tibial stress fractures occur preferentially in the posteromedial cortex of the tibia adjacent to this compartment.

Pathology

Common Injuries & Conditions

Deep Posterior Compartment Syndrome

Pressure elevation in the deep posterior compartment producing medial calf pain and toe flexor weakness, often missed when the superficial compartment is decompressed without addressing the deep compartment.

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