Anterior:
The calf, ankle, and foot are controlled largely by a series of muscles
and tendons that function as a single biomechanical unit. These muscles
work together to lift or lower the heel for virtually any activity that
involves locomotion. All of the parts of the lower leg are interconnected.
For example, when you stand on your toes, you can feel the muscles in the
back of your calf doing most of the work. Because of its structure,
and because it absorbs the impact from activities like running and jumping,
the lower leg is subject to more exercise-related injuries than any other
area of the body. These problems range from bunions and blisters
to stress fractures and ankle sprains, the most common sports injury of
all.
The long, thin extensor digitorum longus muscle actually consists of four combined bellies and their tendons. The belly arises from the tibia and the front edge of the fibula and extends about three-fourths of the way down the lower leg. The four tendons lie close to each other and appear as one tendon that continues down to the front of the ankle. When the tendons reach the back of the foot they separate and extend to the middle and distal phalanges (bones) of the little toes. They extend the toes (separate the toes) and bend the foot toward the leg. The tendons may clearly be seen on the top of the foot when the toes are extended.
The extensor hallucis longus for the most part lies deep in the lower leg. It is a thin, elongated, and flattened muscle that originates from the middle of the fibula (lower leg bone) and tapers into a long, narrow tendon that emerges from between the extensor digitorum longus and the tibialis anterior, extends downward across the ankle and inserts in the top base of the distal phalanx of the big toe. It extends the big toe and assists in flexing the foot.
Lateral:
The peroneous brevis is a flat, elongated muscle located on the outside
of the lower half of the leg. It lies just below the peroneus longus
muscle, originating from the lower surface of the fibula (lower leg bone)
and inserting in the base of the metatarsal bone of the little toe. It
works with the peroneus longus to extend the foot.
The peroneus longus is a superficial muscle that runs along the upper part of the outside of the leg. It originates from the upper shaft of the fibula (lower leg bone), descends across the outer side of the calcaneum (heel bone), crosses the sole of the foot and is inserted in the outer side of the base of the metatarsal bone of the big toe. This muscle works with the peroneus brevis to extend the foot.
The peroneus tertius lies against the peroneus brevis muscle. It is connected to the extensor digitorum longus, and often considered a part of it. The peroneus tertius arises from the lower third of the fibula (lower leg bone) and the adjacent interosseous membrane and continues downward and slightly forward, across the ankle, where it tapers into a narrow, flat tendon that passes over the extensor digitorum brevis and inserts into the fifth metatarsal bone (little toe). This muscle lifts the foot.
The tibialis anterior is a thick and fleshy muscle that, as the name implies, sits on the front of the tibia, the main lower leg bone. It originates from the upper half of the tibia, just below the knee and tapers into a long, prominent tendon about two-thirds of the way down the leg. The long tendon goes through the ankle to insert in the bottom of the inside arch of the foot (in the tarsal bones). This muscle controls the descent of the foot during walking after the heel strikes the ground.
Posterior:
The flexor digitorum longus muscle runs deep in the lower leg from
the middle half of the tibia and tapers into a tendon that ends deep under
the foot at the base of the distal phalanges of the little toes.
It is attached to the flexor hallucis longus muscle, which flexes the big
toe. These muscles work together to flex the toes during the final
push-off in walking and running.
The flexor hallucis longus (flexor of the big toe) is a large superficial muscle that lies on the fibular side of the leg. It is attached to the flexor digitorum longus muscle.
The gastrocnemius muscle is connected at two joints, the knee and the ankle. It consists of a lateral head, a medial head, and their single tendon of insertion. Each head is a thick muscular column, separated from the other by the back of the knee. As they descend, they come together. The medial head is larger and wraps around the leg more towards the front than does the lateral head. The muscular heads end at or slightly above the middle of the leg, where they attach to their tendon. The two heads form the bulging "belly" of the calf of the leg. Their tendon descends and fuses with the tendon of the soleus, which lies just beneath it, forming the Achilles tendon, which inserts in the heel bone. The gastrocnemius muscle propels the body when walking, running, or jumping. It raises the heel, which lifts the body. It also assists, though minimally, in flexing the knee joint.
The soleus is a thick muscle located on the back of the lower leg. It originates from the upper part of the fibula (lower leg bone) and the tendonous arch connecting the head of the fibula to the tibia. The muscle is thickest at its mid-section where its flattened form curves around the deep flexor muscles of the foot and toes. The muscle tapers low, just above the ankle, and its tendon continues on inserting in the middle part of the calcaneum (heel bone). This muscle is used to point the foot or raise the heel, which lifts the body. Its continuous contraction of the soleus prevents the body from falling forward when standing.
The tibialis posterior, as the name indicates, originates from the back of the tibia. It also originates from the inside surface of the fibula (Lower leg bone) and the tissue between the two bony surfaces. It is a deep muscle, but towards the lower end emerges and passes in front of the flexor digitorum longus muscle and tapers into a tendon that inserts into six tarsal bones (navicular, three cuniforms, cuboid, and talus) and the bases of the second, third, and fourth metatarsals. This muscle flexes the foot and, working with the tibialis anterior, turns the sole of the foot inward. It is the strongest support for the arch of the foot.
The plantaris is a very small muscle that lies between the gastrocnemius and soleus muscles. It runs from the lower end of the femur (upper leg bone) to a small area on the bottom of the calcaneum (heel bone). The belly of the muscle is about three or four inches in length and tapers into a long, slender tendon that crosses between the two muscles of the calf and continues to the calcaneus. This muscle works with the gastrocnemius to extend the ankle if the foot is free and bend the knee if the foot is fixed, as when walking.
The area of the back of the knee between the hamstring tendons is called the popliteal region. The popliteal muscle is a thin, flat, triangular muscle that forms the base of this region. It arises from a strong, short tendon (about one inch long) from the femur (thigh bone) and the ligament behind the knee-joint and extends to the shaft of the tibia. This muscle assists in rotating the tibia and is used when bending the knee.
Anterior leg
tibialis
anterior
extensor
hallucis longus & peroneus tertius
extensor
digitorum longus
peroneus
longus & peroneus brevis
Posterior leg
plantaris,
gastrocnemius, achilles tendon
soleus
popliteus,
flexor hallucis longus
tibialis
posterior
flexor
digitorum longus
Links:
Lower leg
Shin Splints (scroll
down on page) link to info on achilles tendon & tendonitis at the bottom
of this page
for injury info Bone Doctor