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The anterior muscles of the leg - want to learn more about it?

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The anterior muscles of the leg

When studying the muscles of the leg, we can examine them by four primary groupings, which are the anterior, fibular/lateral, superficial posterior and deep posterior compartments. These are defined by intermuscular septa and surrounded by the deep fascia of the leg. They usually share innervation and vascularization, so that part will be easier to remember.

The muscles of the anterior leg are a group of muscles which lie within the anterior compartment of the leg, located in the anterolateral region of the leg. They are also known as the dorsiflexors of the leg. 

Key Facts
Tibialis anterior Origin: lateral surface of the tibial and interosseous membrane
Insertion: medial cuneiform and the base of the metatarsal I
Function: dorsiflexion and inversion of the foot
Extensor hallucis longus Origin: the middle of the medial surface of the fibula and interosseous membrane
Insertion: base of the distal phalanx of the great toe
Function: extension of great toe, dorsiflexion of the foot
Extensor digitorum longus Origin: proximal half of the medial surface of the fibula and lateral tibial condyle
Insertion: distal and middle phalanges of the lateral four toes
Function: extension of the lateral four toes, dorsiflexion of the foot
Fibularis tertius Origin: distal medial surface of the fibula
Insertion: dorsomedial surface of the base of the metatarsal V
Function: dorsiflexion and eversion of the foot
Innervation Deep fibular nerve (branch of the common fibular nerve)
Vascularization Anterior tibial artery (branch of the popliteal artery)
Clinical relations Strains, tendon injuries, compartment syndrome, crush syndrome

This article will discuss the anatomy, function and clinical importance related to the anterior muscles of the leg.

Anatomy and supply

The muscles of the anterior comparment of the leg are all palpeable along the anterolateral surface of the leg. Their tendons are also are particularly prominent on the dorsum of the foot. All anterior muscles are innervated by the deep fibular nerve (L4-S1) which is a branch of the common fibular nerve.

Tibialis anterior muscle

The tibialis anterior is the larger and most superficial of the anterior muscles and runs medioinferiorly from the lateral tibia, interosseous membrane and crural fascia. At the level of the lower tibia it becomes tendinous and is led by both extensor retinacula of the foot before inserting at the plantar side of the medial cuneiform and base of the first metatarsal bone.

The tibialis anterior muscle serves as the leading muscle for the neurovascular pathway running towards the ankle (deep fibular nerve, anterior tibial artery and vein).

Extensor digitorum longus muscle

The EDL originates at the lateral tibial condyle, anterior/ventral side of the fibula and interosseous membrane and merges into a tendon above the superior extensor retinaculum. Below the inferior extensor retinaculum it now divides into four tendons inserting at the dorsal aponeurosis and the distal phalanges of the second through fifth toes. About 90% of the people have an additional fifth tendon running towards the lateral foot edge and inserting into the base of the fifth metatarsal bone (fibularis tertius muscle).

Extensor hallucis longus muscle

The EHL has its origin at the medial side of the fibula and interosseous membrane. It merges into a tendon above the superior extensor retinaculum as well. Its insertion is the distal phalanx of the big toe.

Extensor retinacula of the foot

The canal-like extensor retinacula are thickenings of the crural fascia anchoring and leading the tendons of the anterior muscles. The superior extensor retinaculum (transverse crural ligament) runs between fibula and tibia proximal to the malleoli. The Y-shaped inferior extensor retinaculum (cruciate crural ligament) lies more distally and stretches between calcaneus, medial malleolus and plantar aponeurosis.

Recommended video: Muscles of the leg
Origins, insertions, innervation and functions of the muscles of the leg

Function

The common task of the anterior muscles of the lower leg is dorsiflexion of the foot, which occurs at ankle joint.

  • In addition, due to the course of it's tendon,  the tibialis anterior also contributes to the movement of the subtalar joint, by means of inversion or supination of the foot. It also works to support the medial longitudinal arch of the foot. 
Recommended video: Functions of the tibialis anterior muscle
Functions and anatomy of the tibialis anterior muscle shown with 3D model animation.
  • The extensor digitorum longus is involved in extension of the second to fifth digits, occuring at both the metatarsophalangeal and interphalangeal joints
Recommended video: Extensor digitorum longus muscle
Origins, insertions, innervation and functions of the extensor digitorum longus.
  • Similary, the extensor hallucis longus extends the great/big toe at both the metatarsophalangeal and interphalangeal joints of the same digit.
Recommended video: Functions of the extensor hallucis longus muscle
Functions and anatomy of the extensor hallucis longus muscle shown with 3D model animation.

Clincial note

The anterior muscles are indispensable for a natural gait. When paralyzed, a dorsal extension of the foot and toe-lifting become practically impossible. In order to prevent the toes from dragging on the floor the affected patients lift up their legs unusually high and place their toes first (steppage gait).

Because of its relatively rigid and inflexible structure, the anterior compartment of the lower leg is extraordinarily vulnerable to critical increases of pressure, e.g. due to bleeding or edemas (compartment syndrome).

Often they occur after a heavy strain (e.g. a long hike) or trauma. Hereby the muscles swell compromising the nerves and vessels within the compartment which may quickly lead to ischemic muscle necrosis. In this emergency case the muscle compartment has to be immediately decompressed by a surgical incision of the fascias (fasciotomy).

The anterior muscles of the leg - want to learn more about it?

Our engaging videos, interactive quizzes, in-depth articles and HD atlas are here to get you top results faster.

Sign up for your free Kenhub account today and join over 852,397 successful anatomy students.

“I would honestly say that Kenhub cut my study time in half.” – Read more. Kim Bengochea Kim Bengochea, Regis University, Denver

Show references

References:

  • M. Schünke/E. Schulte/U. Schumacher: Prometheus – LernAtlas der Anatomie – Allgemeine Anatomie und Bewegungssystem, 2.Auflage, Thieme Verlag (2007), S.480-481
  • W. Graumann/D.Sasse: CompactLehrbuch der gesamten Anatomie – Band 2 – Bewegungsapparat, Schattauer Verlag (2003), S.202-208
  • J. W. Rohen: Topographische Anatomie, 10.Auflage, Schattauer Verlag (2008), S.140-141,161-163
  • D. Drenckhahn/J. Waschke: Taschenbuch Anatomie, 1.Auflage, Urban & Fischer Verlag/Elsevier (2008), S.94-95

Author:

  • Achudhan Karunaharamoorthy

Illustrators:

  • First - Fourth Illustration Galleries - Liene Znotina
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