Posterior Intermuscular Septum of the Leg

septum intermusculare cruris posterius

The posterior intermuscular septum of the leg separates the lateral (peroneal) compartment from the superficial posterior compartment, running from the posterior fibula to the crural fascia. It defines the posterior boundary of the lateral compartment and the lateral boundary of the superficial posterior compartment.

Region: Lower Leg

Biomechanics

Function & Actions

Separates the lateral and superficial posterior compartments, providing fascial boundaries relevant to compartment syndrome release and surgical approaches.

Clinical Relevance

Clinical Notes

The posterior intermuscular septum is released during the lateral incision in two-incision fasciotomy for lower leg compartment syndrome, decompressing both the lateral and superficial posterior compartments. It is also the boundary for peroneal flap elevation. The short saphenous vein and sural nerve pass near its posterior extent.

Pathology

Common Injuries & Conditions

Lateral-Posterior Compartment Release

Incision through the posterior intermuscular septum during lateral fasciotomy to decompress both the peroneal and superficial posterior compartments simultaneously.