Muscle Anatomy of the Leg

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Questions and Answers

What is the leg?

The leg is the part of the lower limb between the knee and ankle joints.

What are the three compartments of the leg?

The leg is divided into three compartments: Anterior/extensor, lateral (fibular), and Posterior/flexor.

What are the muscles of the anterior compartment of the leg?

Tibialis anterior, Extensor digitorum longus, Extensor hallucis longus, and Fibularis tertius.

What is the origin of the Tibialis Anterior?

The upper two-thirds of the lateral surface of tibia, the interosseous membrane, and the deep fascia overlying it. Signup and view all the answers

What is the insertion of the Tibialis Anterior?

The medial and inferior surfaces of the medial cuneiform bone and adjacent parts of the first metatarsal. Signup and view all the answers

What is the origin of the Extensor Hallucis Longus?

The middle two-fourths of the medial surface of the fibula and the adjacent interosseous membrane. Signup and view all the answers

What is the insertion of the Extensor Hallucis Longus?

The base of the distal phalanx of the great toe. Signup and view all the answers

What is the origin of the Extensor Digitorum Longus?

The upper three-quarter of the medial surface of the fibula extending superiorly, the lateral condyle of the tibia, and the deep fascia. Signup and view all the answers

What is the insertion of the Extensor Digitorum Longus?

The dorsal surfaces of the bases of the middle and distal phalanges of the lateral four toes. Signup and view all the answers

What is the origin of the Fibularis Tertius?

The lower third of the anterior surface of the fibula. Signup and view all the answers

What is the insertion of the Fibularis Tertius?

The base of the fifth metatarsal. Signup and view all the answers

What does the lateral compartment of the leg contain?

It contains the peroneal longus, peroneal brevis muscles, and the superficial peroneal nerve. Signup and view all the answers

Where does the blood supply of the lateral compartment of the leg come from?

Branches of the peroneal artery. Signup and view all the answers

Where do the veins of the lateral compartment of the leg drain?

Into the small saphenous vein. Signup and view all the answers

What is the origin of the Peroneus Longus?

The head and the upper two-third of the peroneal surface of the fibula and from intermuscular septa. Signup and view all the answers

What is the insertion of the Peroneus Longus?

The lateral side of the base of the first metatarsal and the adjoining part of the medial cuneiform. Signup and view all the answers

What nerve innervates the Peroneus Longus?

The superficial peroneal nerve (L5 S1). Signup and view all the answers

What nerve innervates the Peroneus Brevis ?

The superficial peroneal nerve (L5, S1) Signup and view all the answers

What is the action of the Peroneus Brevis?

It everts and weakly plantarflexes the foot. Signup and view all the answers

What is the role of the Fibular Retinaculum?

Fibular retinacula bind the tendons of the peroneus longus and brevis muscles to the lateral side of the foot. In addition, a superior fibular retinaculum extends between the lateral malleolus and the calcaneus. Signup and view all the answers

Study Notes

Muscle of the Leg - Learning Outcomes

Students will be able to describe the anatomy of the leg.
Students will be able to list and explain the muscles of the leg and their compartments.
Students will be able to state the origin, insertion, innervation, and action of the leg muscles.

The Leg

The leg is the portion of the lower limb between the knee and ankle joints.
Proximally, major structures pass through the popliteal fossa, between the thigh and leg.
Distally, most structures pass through the tarsal tunnel, between the leg and foot.

Compartments of the Leg

The interosseous membrane, intermuscular septa, and deep fascia divide the leg into three compartments.
Anterior/extensor compartment (dorsiflexor and foot inverter)
Lateral (fibular) compartment (foot everters)
Posterior/flexor compartment (plantarflexor and foot everters)

Compartments of the Leg - Muscle Movements

Muscles in each compartment perform specific movements.
Anterior compartment: dorsiflexes the ankle, extends the toes, and inverts the foot.
Lateral compartment muscles: evert the foot.

Anterior Compartment of the Leg

Located anterior to the interosseous membrane.
Between the tibial shaft's lateral surface and the fibular shaft's medial surface.
Bounded anteriorly by the deep fascia of the leg and skin.

Tibialis Anterior

Most anterior and medial muscle in the anterior compartment.
Origin: upper two-thirds of the tibia's lateral surface, and interosseous membrane
Also originates from deep fascia overlying tibia
Attachments: medial and inferior surfaces of the medial cuneiform, and the adjacent parts of the first metatarsal (associated with the great toe.).
Action: dorsiflexion of the ankle joint, inverts the foot at the intertarsal joints. During walking, it provides dynamic support for the medial arch of the foot.

Extensor Hallucis Longus

Lies next to and overlaps the tibialis anterior muscle.
Origin: middle two-forths of the fibula's medial surface, and the adjacent interosseous membrane.
Insertion: the base of the great toe's distal phalanx.
Action: extends the great toe. Also dorsiflexes the foot at the ankle joint.

Extensor Digitorum Longus

Most posterior and lateral of the anterior compartment muscles.
Origin: upper three-quarters of the fibular medial surface (extends superiorly), lateral condyle of the tibia, and deep fascia.
Insertion: dorsal surfaces of the bases of the middle and distal phalanges of the lateral four toes.
Action: extends the lateral four digits and dorsiflexes the foot at the ankle joint.

Fibularis Tertius

Origin: lower third of the anterior surface of the fibula.
Its tendon descends into the foot with the tendon of extensor digitorum longus.
On the dorsal aspect of the foot, it deviates laterally.
Insertion: base of the fifth metatarsal.
Action: assists in dorsiflexion and possibly eversion of the foot.

Lateral Compartment of the Leg

Lies between the fibula's peroneal surface and the leg's deep fascia.
Bounded anteriorly and posteriorly by the anterior and posterior intermuscular septa.
Contains the peroneus longus and brevis muscles, and the superficial peroneal nerve. Blood supply is from branches of the peroneal artery, and veins drain into the small saphenous vein.

Peroneus Longus

Origin: head and upper two-thirds of the fibula's peroneal surface, and intermuscular septa.
Insertion: lateral side of the first metatarsal and medial cuneiform.
Nerve Supply: Superficial peroneal nerve (L5 S1).
Action: everts and plantarflexes the foot; maintains the lateral longitudinal and transverse arches of the foot.

Peroneus Brevis

Origin: Lower two-thirds of the fibula, anterior to peroneus longus.
Insertion: tubercle at the base of the fifth metatarsal.
Nerve Supply: Superficial peroneal nerve (L5, S1).
Action: everts and weakly plantar flexes foot.

Fibular Retinaculum

Fibular retinacula bind the tendons of peroneus longus and brevis.
Superior fibular retinaculum extends between the lateral malleolus and the calcaneus.

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Description

This quiz focuses on the anatomy of the leg, including its muscles and compartments. Students will learn to describe the origin, insertion, innervation, and action of the leg muscles. Test your understanding of the leg's anatomy and muscle movements in this comprehensive assessment.