Now, if we look at a cross section of the lower leg, we can see that the fascia sends intermuscular septa that together with the interosseous membrane between the tibia and fibula divide the lower leg into four compartments
In the middle of the night, Hans Spaans finds himself being overwhelmed by cramps slowly tightening up the muscles in his arms, back, thighs and calves until his whole body is a knot of pain, and he's practically paralyzed.
In humans all of that force is entering the body through a single point, our heel, and then traveling up our leg, so we rely on the muscles of our lower legs to absorb that energy and protect our joints.
The extent of those lower-leg injuries necessitated two deep incisions—they're called medial and lateral fasciotomies—to release the pressure caused by the exploded tibia and also to allow blood to flow back into the lower leg.