Author: Jana Vasković•Reviewer: Dimitrios Mytilinaios MD, PhDLast reviewed: September 30, 2021Reading time: 6 minutes

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Extensor digitorum longus muscle (Musculus extensor digitorum longus)

Extensor digitorum longus (EDL muscle) is a feather-like muscle of the anterior (extensor) compartment the leg. As well as EDL muscle, this compartment likewise contains the tibialis anterior, extensor hallucis longus and fibularis (peroneus) tertius muscles.

You are watching: The insertion of the extensor digitorum branches into __________.

Since every these muscles cross the dorsal facet of the fish eye joint, their common role is dorsiflexion the the foot. Together the extensor digitorum longus also crosses the subtalar, metatarsophalangeal and also interphalangeal joints of the foot, it also everses the foot and also extends the toes.

This write-up will comment on the anatomy and role of the extensor digitorum longus muscle.

Key facts about extensor digitorum longus muscle
Origin(Proximal fifty percent of) medial surface of fibula, lateral tibial condyle, interosseus membrane
InsertionDistal and middle phalanges of digits 2-5
ActionMetatarsophalangeal and interphalangeal joints 2-5: toe extension;Talocrural joint: Foot dorsiflexion;Subtalar joint: Foot eversion
InnervationDeep fibular nerve (L5, S1)
Blood supplyAnterior tibial, fibular, anterior lateral malleolar, lateral tarsal, metatarsal, plantar, and digital arteries

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Extensor digitorum longus originates indigenous the inferior component of the lateral tibial condyle, the proximal half of the medial surface of fibula and also the anterior surface ar of the interosseus membrane (its many superior part). The part of its beginning at tibial condyle is fused through the originating yarn of the fibularis longus muscle.

After that is origin, the muscle descends inferiorly and also just over the ankle provides off a tendon that passes under the exceptional extensor retinaculum and through the worse extensor retinaculum. Due to the fact that all the muscle fibers affix on one next of the tendon, this muscle is classified together an unipennate muscle.

Within the inferior extensor retinaculum, the tendon splits right into the four smaller tendons that all together room wrapped through a synovial sheath. ~ exiting the retinaculum, the four tendons diverge in the direction of the toes. Superficially come the proximal phalanges, each tendon widens and forms the triangle dorsal digital expansions (or extensor hoods). The medial section of every extensor hood blends v the corresponding tendons that the lumbrical muscles, if the lateral components related come the number 2-4 room joined by the tendons the the extensor digitorum brevis muscle.

The extensor hoods course over the proximal phalanges, and at the level of the base of middle phalanges, every of them more divides into a main band and also two lateral bands. The central bands insert come the basic of the distal phalanges that lateral four toes, respectively. The lateral bands continue over the center phalanges and also just proximally to the distal phalanges, every pair of them merges right into a single tendinous band. This newly created bands insert to the bases of center phalanges the lateral 4 digits.

Relations


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This muscle is the most lateral of every the muscles in the extensor compartment and lies laterally come the tibialis anterior and also extensor hallucis longus. Anterior tibial artery and vein pass in between the extensor digitorum longus and the tibialis anterior.

Being within the inferior extensor retinaculum, the distal component of the muscle the cross the anterior next of the ankle joint. If traversing the retinaculum, the tendon that extensor digitorum longus sits medially to the tendon that fibularis tertius and laterally to the extensor hallucis longus tendon. In the dorsum the the foot, tendons that the muscle food superficially to the extensor digitorum brevis muscle.

Innervation

The extensor digitorum longus is innervated through the deep fibular nerve (L5, S1), a branch the the usual fibular nerve.


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Blood supply

The leg portion of the muscle is provided by two arteries that the leg; the proximal component is offered by the anterior tibial artery, when the distal component receives blood indigenous the fibular artery.

The tendons the the muscle room vascularized by the anterior lateral malleolar, lateral tarsal, metatarsal, plantar and digital arteries.

Function

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Dorsiflexion of the foot

The primary activity of the extensor digitorum longus is to extend the lateral 4 toes in ~ metatarsophalangeal joint. This means that when acting independently, that is unable to extend the entire length of the toes, expanding only in ~ metatarsophalangeal, while at the interphalangeal joints the toes stay flexed. However, contracting in addition to lumbricals which space the main extensors of the interphalangeal joints, this muscle contributes to expansion at every joint between the skeletal of the lateral four toes.

Acting in synergy through tibialis anterior, extensor hallucis longus and fibularis tertius, this muscle participates in dorsiflexion of the foot once their proximal attachments space fixed. Once the distal attachments room fixed and the body is in the anatomical position, all 4 muscles carry the trunk and also lower limb to the front. This activity moves the body weight bearing allude from the proximal to distal part of foot.

All of these actions are essential for the gait cycle; the dorsiflexion angulates and lifts the foot above the walking surface, if the toe expansion keeps the toes expanded until the hoe hits the ground.

Go ahead and also quiz yourself on the extensor digitorum longus and also other muscle of the foot to consolidate what girlfriend learned therefore far!


Sources

References:

Moore, K. L., Dalley, A. F., & Agur, A. M. R. (2014). Clinically Oriented Anatomy (7th ed.). Philadelphia, PA: Lippincott Williams & Wilkins.Netter, F. (2019). Atlas of human being Anatomy (7th ed.). Philadelphia, PA: Saunders.Palastanga, N., & Soames, R. (2012). Anatomy and human movement: framework and function (6th ed.). Edinburgh: Churchill Livingstone.Standring, S. (2016). Gray"s Anatomy (41tst ed.). Edinburgh: Elsevier Churchill Livingstone.

Layout:

Abdulmalek Albakkar

Illustrators:

Extensor digitorum longus muscle (Musculus extensor digitorum longus) - Liene ZnotinaDorsiflexion that the foot - Paul Kim

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