The Foot

A common problem, found in athletes and in other patients, is that when the calf muscle becomes tight and shortened, the foot tends to assume a position with downward-pointing toes. The muscles that hold the foot up—the foot flexors situated at the front of the lower leg between the tibia and fibula—are thus forced to work with constantly raised tension (tone)

TABLE 12-3 The Main Muscles Producing Movement of the Ankle Joint

Function

Muscle

Proximal Attachment

Distal Attachment

Innervation

Action

Dorsiflexors

Anterior

Lateral condyle and superior half of

Medial and inferior surface

Deep fibular

Dorsiflexes and inverts foot

tibialis

the lateral surface of tibia

of medial cuneiform

(peroneal) nerve

bone and base of first

(L4 and L5)

metatarsal bone

Extensor

Middle part of anterior surface

Dorsal aspect of base of

Deep fibular

Extends great toe and

hallucis

of fibula and interosseous

distal phalanx of great toe

(peroneal) nerve

dorsiflexes foot

longus

membrane

(hallux)

(L5 and S1)

Extensor

Lateral condyle of tibia, superior

Middle and distal phalanges

Deep fibular

Extends lateral four digits

digitorum

three fourths of anterior surface of

of lateral four digits

(peroneal) nerve

and dorsiflexes foot

longus

fibula, and interosseous membrane

(L5 and S1)

Fibularis

Inferior third of anterior surface

Dorsum of base of fifth

Deep fibular

Dorsiflexes foot and helps

(peroneus)

of fibular and interosseous

metatarsal bone

(peroneal) nerve

eversion of foot

tertius

membrane

(L5 and S1)

Superficial

Gastrocnemius

Lateral head: lateral condyle of femur

Posterior surface of

Tibial nerve (S1

Plantarflexes foot; raises heel

muscles of

Medial head: popliteal surface of femur,

calcaneus via tendo

and S2)

during walking and during

posterior

superior to medial condyle

calcaneus

flexion of knee joint

compartment

Soleus

Posterior head of fibula, superior

Posterior surface of

Tibial nerve (S1

Plantarflexes foot and

fourth of posterior surface of

calcaneus via tendo

and S2)

stabilizes leg on foot

fibula, soleal line, and medial

calcaneus

border of tibia

Plantaris

Inferior end of lateral supracondylar

Posterior surface of

Tibial nerve (S1

Assists gastrocnemius in

line of femur and oblique

calcaneus via tendo

and S2)

plantar flexing foot and

popliteal ligament

calcaneus

flexing knee joint

Deep muscles

Posterior

Interosseous membrane, posterior

Tuberosity of navicular,

Tibial nerve

Plantarflexes and inverts foot

of posterior

tibialis

surface of tibia inferior to soleal

cuneiform, and cuboid bones

(L4 and L5)

compartment

line, posterior surface of fibula

and fourth metatarsal bone

Flexor

Medial part of posterior surface of

Base of distal phalanges of

Tibial nerve

Flexes lateral four digits and

digitorum

tibia, inferior to soleal line, and

lateral four digits

(L4 and L5 )

plantarflexes foot; supports

longus

by a broad aponeurosis to tibia

longitudinal arch of foot

Flexor hallucis

Inferior two thirds of posterior

Base of distal phalanx of

Tibial nerve

Flexes great toe at all joints and

longus

surface of fibula and inferior part

great toe

(L4 and L5 )

plantarflexes foot; supports

of interosseous membrane

longitudinal arch of foot

Muscles of lateral

Fibularis

Head and superior two thirds of

Base of first metatarsal

Superficial fibular

Everts and weakly

compartment

(peroneus)

lateral surface of fibula

bone and medial cuneiform

(peroneal) nerve

plantarflexes foot

longus

bone

(L5, S1, and S2)

Fibularis

Inferior two-thirds of lateral surface

Dorsal surface of tuberosity

Superficial fibular

Everts and weakly

(peroneus)

of fibula

on lateral side of base of fifth

(peroneal) nerve

plantarflexes foot

brevis

metatarsal bone

(L5, S1, and S2)

in order to hold the foot in its normal position. Such tension may lie behind the pain that is experienced in the lower leg when an athlete trains too much in one session or runs on hard surfaces.

The foot can move along two axes: mediolateral for flexion and extension and anteroposterior for pronation and supination. Extension and flexion take place between the talus and both the tibia and the fibula at the ankle joint. Supination and pronation take place between the talus and both the navicular bone and the calcaneus at the subtalar joint. Supination and pronation take place simultaneously between several articulating surfaces that together form the subtalar joints. Movements of the ankle and subtalar joints are independent of each other. If the muscles that control these two joints are unable to prevent movements that are too great or too sudden, the joint is still protected by the ligaments of the foot.

The ankle ligaments arise from the prominent lower ends of the tibia and fibula (the malleoli) and spread out down toward the articulating ankle bones. Thus the medial ligament of the ankle, the deltoid ligament (Fig. 12-7), arises from the medial malleolus of the tibia and is inserted into the calcaneus, talus, and navicular bones.

Three separate ligaments make up the lateral ligament. They all arise from the lateral malleolus of the fibula. One ligament extends forward and is inserted into the talus, the second passes downward to be attached to the calcaneus, and the third

Medial [deltoid] collateral ligament-:

Posterior tibiotalar part Tibiocalcanea part Anterior tibiotalar part N Tibionavicular partx Tibialis posterior, tendon Tibialis anterior, tendon -

Plantar tarsometatarsal ligaments

Medial [deltoid] collateral ligament-:

Plantar tarsometatarsal ligaments

Groove for fibularis longus tendon

Groove for fibularis longus tendon

Anterior tibiofibular ligament Anterior talofibular ligament Lateral malleolus Calcaneofibular ligament

Calcaneal tendon* \ . tendon*

Long plantar ligament

Calcaneonavicular ligament

-Fibula Tibia

Posterior tibiofibular ligament

Sustentaculum tali Plantar calcaneonavicular ligament

Calcaneal tuberosity Long plantar ligament

Plantar calcaneonavicular ligament

Lateral talocalcaneal ligament ■ Talocalcaneal interosseous ligament , Dorsal cuboideonavicular ligament * Dorsal cuneonavicular ligament

Dorsal metatarsal ligaments

Deep transverse metatarsal ligaments

Dorsal tarsometatarsal ligaments 1 Fibular [peroneus] brevis, tendon Calcaneocuboid ligament

Long plantar ligament

Calcaneonavicular ligament

Bifurcate ligament

Figure 12-7 Ligaments and tendons of the foot. A, Medial view. B, Lateral, view.

Bifurcate ligament

Figure 12-7 Ligaments and tendons of the foot. A, Medial view. B, Lateral, view.

extends backwards toward the posterior part of the talus. The origin of the deltoid (medial) ligament corresponds to the axis of motion of the ankle joint; thus it is always taut. The origin of the lateral ligament is situated below the axis of motion; thus its posterior part is taut when the foot points upward (dorsiflexion) and the anterior part is taut when the ankle is stretched (plantar flexion). When injured, the ligament is either partially ruptured or completely torn. In many cases, the ligament remains intact, but the malleolus is broken off.

Muscles of the Foot. Nine muscles control the major movement of the foot at two axes: mediolateral (flexion and extension) and anteroposterior (pronation and supination). The most important flexor is the triceps surae, although its movement is assisted by other muscles. The most important extensors are at the front of the leg between the tibia and fibula. Their tendons can easily be palpated on the top of the foot at the base of the tibia. Pronation is brought about by the two muscles whose tendons can be felt beneath the lateral malleolus of the tibia. Supination is produced mainly by the three muscles whose tendons pass behind and beneath the medial malleolus of the tibia (Fig. 12-8 and Table 12-3).

The Arches of the Foot. The articulated foot exhibits three distinct arches: a medial and a lateral longitudinal arch and a transverse arch. The medial longitudinal arch is formed by the calcaneus, talus, navicular, medial cuneiform, and first metatarsal bone. The lateral longitudinal arch consists of the calcaneus, cuboid, and fifth metatarsal bone (Fig. 12-9).

The transverse arch includes the cuboid and cuneiform bones and continues at the bases of the metatarsals.

The arches serve several purposes: They protect the nerves, blood vessels, and muscles on

Tibialis anterior-

Extensor digitorum longus '

Extensor hallucis longus

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