Dance Anatomy & Kinesiology

The Ankle and Foot 311

Attachments and Primary Actions of Extensor Hallucis and Digitorum Longus

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

Extensor hallucis longus

(ek-STEN-sor HAL-u-sis LON-gus)

Anterior fibula and

adjacent interosseus

membrane at the middle

half of leg

Upper surface of base of

distal phalanx of great

toe (hallux)

Great toe extension

A-F dorsiflexion

Foot inversion

Extensor digitorum longus

(ek-STEN-sor di-ji-TOR-um LON-gus)

Lateral condyle of tibia

Upper anterior fibula

Upper surface of lesser

toes and their extensor

expansions

Lesser toe extension

A-F dorsiflexion

Foot eversion

FIGURE 6.13 The extensor

hallucis longus (right foot,

anterior view).

FIGURE 6.14 The extensor

digitorum longus and peroneus

tertius (right foot, anterior view).

Extensor Hallucis Longus

The great toe or hallux has an extensor of its own, called the extensor hallucis longus (EHL) (figure

6.13). This is fitting, in that the great toe is very important in locomotion. The superior muscular portion

of the extensor hallucis longus (extensor, extend + hallux, great toe + longus, long) is located deep to

the tibialis anterior and peroneus tertius, but it rises to the surface to lie between these muscles in the

distal third of the lower leg. Its tendon crosses the front of the ankle, just lateral to the tibialis anterior,

and runs slightly medially to attach to the dorsal surface of the great toe. As its name implies, it has

a primary action of extending the first MTP joint and the IP joint of the great toe. Due to its crossing

anterior to the ankle joint axis and its medial line of pull, this muscle can also assist with ankle-foot

dorsiflexion and foot inversion.

Palpation: The tendon of this muscle is located

just lateral to the tibialis anterior at the front of

the ankle. If you bring the big toe up toward the

shin (hallux extension) the tendon will become

more prominent and you can palpate the tendon

from the top of the big toe and along the dorsum

of the foot.

Extensor Digitorum Longus

The extensor digitorum longus (EDL; extensor,

extend + digit, finger or toe + longus, long) and

the associated peroneus tertius are the most

laterally located muscles of the anterior crural

muscles (figure 6.14). The extensor digitorum

longus has a long tendon that begins about

halfway down the lower leg; and when it crosses

the front of the ankle joint, this tendon divides

into four slips that attach distally to the dorsal

surface of each of the lesser toes. As the name

extensor digitorum longus implies, its primary

action is to extend the toes (extension of the

MTP and both proximal and distal IP joints of

the four lesser toes). Crossing the front of the

ankle with tendons running laterally, it also can

produce ankle-foot dorsiflexion and foot eversion.

The extensor digitorum longus can work together

with the tibialis anterior as a helping synergist,

neutralizing out the inversion of the tibialis ante-

rior to allow the often-desired neutral dorsiflexion

of the ankle-foot.

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