The Ankle and Foot 307In addition to protecting and dividing the muscles
of the plantar area of the foot into compartments,
this fascial structure is very important for support of
the medial longitudinal arch of the foot. It creates a
trusslike structure (Frankel and Nordin, 1980), which
is a rigid structure composed of elements that are
fastened at their base to prevent movement between
the individual elements and to maintain their shape
(figure 6.8A). Thus, the rearfoot and forefoot are held
together by the plantar fascia, and the flattening of
the arch that would be expected during standing and
bearing weight on the foot is prevented. Furthermore,
due to its attachment onto the base of the phalanges,
when the toes extend, such as before toe-off in walk-
ing, the band is tightened by being stretched across
the metatarsophalangeal joints (windlass effect) as
shown in figure 6.8B. This tightening of the band
tends to raise the medial longitudinal arch and supi-
nate the foot, which in turn locks the midtarsal joints
and makes the foot more stable for toe-off in walk-
ing and running (Levangie and Norkin, 2001). This
support of the arch and stabilization of the foot via
the windlass mechanism are also operative whenever
dancers go on demi-pointe (figure 6.8C).Deep Fascia and Intermuscular Septa
of the Lower Leg
Strong sheets of fascia divide muscles of the lower leg
and foot into three primary compartments—anterior,
posterior, and lateral. The posterior compartmentFIGURE 6.7 The plantar fascia (right foot, inferior
view).
FIGURE 6.8 The function of the plantar fascia (right foot, medial view). (A) Tether of a truss in standing, (B) windlass
effect with metatarsophalangeal extension, (C) windlass effect with demi-pointe.