Muscles of the leg include muscles of the thigh and foot. Leg muscles functions to perform all the motions and movements of the lower limb like standing, running, dancing etc. Leg muscles can be divided into 3 compartments: Anterior compartment, posterior compartment and lateral compartment.
Muscles of the Anterior Compartment of the Leg
Some of the major muscles of anterior compartment of the leg are:
- Quadriceps femoris
- Articularis genu
- Tensor fasciae latae
- Tibialis anterior
- Extensor hallucis longus
- Extensor digitorum longus
- Peroneus tertius
Quadricep femoris is thus referred to as because it is composed of 4 mucles: rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius. It’s supplied by the femoral nerve. It creates the majority of the mass on the anterior aspect of the thigh and is the strongest extensor of the knee joint.
All the parts of quadriceps cross only 1 joint, i.e., knee joint, with the exception of rectus femoris which crosses 2 joints, i.e., hip and knee joints.
Originates from the anterior surface of the lower part of the shaft of the femur, few centimeters above the patellar articular margin. Articularis genu is made up of 3 or 4 muscular skids that are said to be a separated part of the vastus intermedius.
Sarotius muscle corkscrew obliquely through the thigh from lateral to medial side to reach the posterior aspect of the medial condyle of femur. Sartorius muscle appears from the anterior superior iliac spine and upper half of the notch immediately below it.
Tensor Fasciae Latae
It is a thick short muscle and is located at the junction of the gluteal region at the upper part of the front of the thigh. It abducts the hip joint and keeps the extended position of the knee joint via the iliotibial tract.
It is a spindle-shaped multipennate muscle. Tibialis anterior is the most medial and superficial dorsiflexor of the foot, which is located against the lateral surface of the tibia. The muscle fibres converge below to create a tendon that is related to the lower 1/3rd of the lateral surface of the tibia. It is innervated by the deep peroneal nerve.
Extensor Hallucis Longus
Extensor halluces longus muscle originates from the middle 2/4th (posterior part) of the medial surface of the shaft of fibula. It performs the extension of the phalanges of the big toe and dorsiflexion of the foot.
Extensor Digitorum Longus
The extensor digitorum longus muscle is the most posterior together with lateral of the muscles in the front compartment of the leg. Just like the tibialis anterior muscle, it also emerges via deep fascia. It performs the extension of MP, PIP, and DIP joints of the lateral four toes.
Peroneus tertius originates from the lower 1/4th of the anterior surface of the fibula. It is inserted into the dorsal surface (medial part) of the base of the 5th metatarsal bone. Peroneus tertius also perform dorsiflexion of the foot.
Muscles of the Posterior Compartment of the Leg
Some of the major muscles of posterior compartment of the leg are:
- Superficial muscles of the posterior compartment of the leg:
- Deep muscles of the posterior compartment of the leg:
- Flexor digitorum longus
- Flexor hallucis longus
These muscles on the back of the thigh are termed the hamstring muscles (Latin ham = back of thigh). Yet conventionally the short head of the biceps femoris isn’t incorporated in the hamstring group. All the hamstrings muscles are:
Superficial Muscles of the Posterior Compartment of the Leg
The superfcial group of muscles in the posterior compartment of the leg comprises three muscles-the gastrocnemius, plantaris, and soleus, all of which insert onto the heel (calcaneus) of the foot and plantarflex the foot at the ankle joint.
It is the largest and most superficial muscle of the posterior compartment. It includes 2 heads- medial and lateral. Gastrocnemius muscle is the main plantar flexor of the foot in the ankle when the knee is extended and it is also a flexor of the knee.
It’s a multipennate muscle being located deep to the gastrocnemius and is supplied by 2 branches of the tibial nerve. The tendon of soleus fuses with that of gastrocnemius to create tendocalcaneus, that is added into the middle 1/3rd of the posterior surface of calcaneum.
The Plantaris muscle appears from the lower 1/3rd of the lateral supracondylar line and the adjoining part of the oblique popliteal ligament. It’s a small muscle with a short gut and long slim tendon. It is located between the gastrocnemius and soleus.
Deep Muscles of the Posterior Compartment of the Leg
There are four muscles in the deep posterior compartment of the leg – the popliteus, ﬂexor hallucis longus, flexor digitorum longus, and tibialis posterior.
It’s a thin, flat, triangular muscle, which forms the inferior part of the floor of the popliteal fossa. It unlocks the locked knee by rotating the femur laterally during first phases of flexion of the knee.
Flexor Digitorum Longus
The flexor digitorum longus ﬂexes the lateral four toes. It originates on the medial side of the posterior compartment of the leg and inserts into the lateral four digits of the foot. It is involved with gripping the ground during walking and propelling the body forward off the toes at the end of the stance phase of gait. It is innervated by the tibial nerve.
Flexor Hallucis Longus
The flexor hallucis longus muscle originates on the lateral side of the posterior compartment of the leg and inserts into the plantar surface of the great toe. The flexor hallucis longus flexes the great toe.
Muscles of the Lateral Compartment of the Leg
Muscles of the lateral compartment of the leg are:
Muscles of the Medial Compartment of the Thigh
The muscles of the medial compartment of the thigh are ordered into 3 layers:
- Anterior (first) layer is composed of pectineus, adductor longus, and gracilis.
- Middle (second) layer contains adductor brevis.
- Posterior (third) layer is composed of adductor magnus.
Muscles of the Foot
The muscles of the foot mainly customize and improve the actions of the long tendons and help fine movements of the toes.
Muscles of the Dorsum of the Foot
Extensor Digitorum Brevis
It’s a small muscle situated on the lateral part of the dorsum of the foot, deep to the tendons of extensor digitorum longus. It’s the only muscle on the dorsum of the foot and creates a fleshy swelling anterior to the lateral malleolus.
Extensor Hallucis Brevis
The extensor hallucis brevis originates in conjunction with the extensor digitorum brevis. Its tendon attaches to the base of the proximal phalanx of the great toes. The muscle extends the metatarsophalangeal joint of the great toe and is innervated by the deep fibular nerve.