Dance Anatomy & Kinesiology

314 Dance Anatomy and Kinesiology

regularly during standing posture to keep the body from falling forward (Basmajian and DeLuca, 1985).

Although some controversy still exists, there is some support for the concept that the medial half of

the soleus may also act as an invertor of the calcaneus (Levangie and Norkin, 2001). The soleus and

gastrocnemius together contain three muscle bellies and hence are termed the triceps surae (L. tri,

three + caput, head + sura, calf of the leg).

Palpation: Although much of the soleus is covered by the more superficial gastrocnemius, the soleus

protrudes on both sides of the gastrocnemius in the lower calf. You can feel the soleus contracting in

the lower calf area when you go onto demi-pointe while sitting in a chair with the knee bent.

Posteromedial Crural Muscles

The posteromedial crural or deep posterior crural muscles are located in the deep posterior compart-

ment of the leg. They include the popliteus, flexor hallucis longus, flexor digitorum longus, and tibialis

posterior muscles. The primary function of the popliteus is at the knee, as was discussed in chapter 5.

Although the remaining three muscles are located posteriorly, as they approach the ankle they course

medially, running behind the medial malleolus to attach onto the foot. The resultant line of pull of these

three muscles allows them to all function as inverters of the foot as well as plantar flexors.

Tibialis Posterior

The tibialis posterior (tibial, tibia + posterior, toward the back) lies

deep to the triceps surae in the medial portion of the deep posterior

compartment. It originates from the upper interosseous membrane

and adjacent portions of the tibia and fibula. It runs medially down

the back of the leg, passes under the medial malleolus, and then runs

forward to attach onto the inferior surface of the navicular bone and

(by means of fibrous expansions) into adjacent tarsal bones and into

the bases of the metatarsals as seen in figure 6.17. Its line of pull

makes it a powerful invertor of the foot whether the foot is plantar

flexed or dorsiflexed. The tibialis posterior also assists with weight-

bearing ankle-foot plantar flexion. The tibialis posterior is considered

an important muscle for preventing undesired pronation; and with its

fibrous expansions and sling-like support of the talus, it is in a desir-

able position to help maintain the medial longitudinal arch and lock

the tarsal joints during movements. Due to these latter roles, the tibi-

alis posterior is considered a key medial dynamic stabilizer of the foot

(Frey and Shereff, 1988; Levangie and Norkin, 2001). The importance

of the tibialis posterior in this function is evidenced by the eversion,

loss of height of the medial longitudinal arch, and forefoot abduction

that accompany rupture of the tibialis posterior tendon.

Palpation: The tendon of the tibialis posterior can be palpated just

below the medial malleolus as it travels forward toward the navicular.

Pointing the foot and bringing the big toe inward (ankle-foot plantar

flexion and inversion of foot) will make the tendon become more

prominent.

Attachments and Primary Actions of Tibialis Posterior

Muscle Proximal attachment(s) Distal attachment(s) Primary action(s)

Tibialis posterior

(tib-ee-A-lis)

Posterior aspect of upper half

of interosseous membrane and

adjacent tibia and fibula

Plantar surface of navicular, with

offshoots to adjacent bones

Foot inversion

A-F plantar flexion

Supports arch

FIGURE 6.17 The tibialis posterior

(right foot, posterior view).