Dance Anatomy & Kinesiology

308 Dance Anatomy and Kinesiology

can be further subdivided into the superficial poste-

rior compartment and the deep posterior compart-

ment as seen in figure 6.9. These compartments

provide a functional division of muscles in that all

of the muscles in a given compartment share at

least one common action at the ankle-foot complex.

The bone and strong fascia forming boundaries for

each compartment limit the compartment’s ability

to expand, which in select individuals can lead to

undesired increases in compartment pressures.

Retinaculum

Thickened bands of connective tissue called reti-

naculum (L. band, halter) are located around the

ankle and foot that help hold tendons in place and keep

them from bowing forward across the front of the ankle

or sliding in front of the medial or lateral malleolus.

For example, the superior peroneal (fibular) retinacu-

lum extends from the lateral malleolus to the fascia of

the back of the leg and lateral side of the calcaneus

(figure 6.10). It functions to help hold the peroneal

muscles in place behind the lateral malleolus.

Tendon Sheaths

Many of the tendons in the foot are encased by

synovial tissue, forming tendon sheaths that protect

the tendons from excessive friction. For example,

on the dorsum of the foot, tendon sheaths surround

the tendons of the tibialis anterior, extensor hallu-

cis longus, and extensor digitorum longus muscles

(figure 6.10).

Heel Pad

The heel pad is composed of fat cells located within

chambers formed by fibrous tissue walls (septa)

constructed in a manner to withstand strain and pres-

sure. This pad has been found to be very important

for shock absorption (Jorgensen, 1985), and loss

of the shock absorbency of this fat pad has been

shown to be associated with an increased shock

wave amplitude at heel strike and increased soleus

activity and load on the Achilles tendon. The effec-

tiveness of the cushioning offered by the heel pad

tends to decline with age, with noticeable decline in

most individuals past 40 years of age (Levangie and

Norkin, 2001).

Sesamoids

Two small sesamoid bones lie beneath the head of

the first metatarsal, located within the tendon of the

flexor hallucis brevis (figure 6.2A, p. 299). Their

function is similar to that of the patella located in

the quadriceps femoris at the knee. They increase

the moment arm of the muscle within which they are

located, increasing the muscle’s ability to produce

torque. They also help distribute the load and pres-

sure beneath the metatarsal head during walking and

running. Furthermore, they help protect the tendons

of their associated muscle and the tendon of the

flexor hallucis longus that runs between them—all

of which without the sesamoids would be subjected

to great compression forces with each step or when

one goes on demi-pointe.

FIGURE 6.9 Compartments of the lower leg (right leg, transverse section).