Flexor Digitorum Longus Muscle – Anatomy, Nerve Supply

Last updated: February 8, 2026Reviewed date: February 8, 2026Reading time: 3 min read
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Flexor Digitorum Longus Muscle/The flexor digitorum longus is situated on the tibial side of the leg. At its origin, it is thin and pointed, but it gradually increases in size as it descends. This muscle serves to curl the second, third, fourth, and fifth toes...

For severe symptoms, danger signs, pregnancy, child illness, or sudden worsening, seek urgent medical care.

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Article Summary

Flexor Digitorum Longus Muscle/The flexor digitorum longus is situated on the tibial side of the leg. At its origin, it is thin and pointed, but it gradually increases in size as it descends. This muscle serves to curl the second, third, fourth, and fifth toes (flexion of phalanges II-V). Flexor digitorum longus is a thin muscle that belongs to the deep posterior muscles of the leg. It runs...

Key Takeaways

  • This article explains Anatomy of Flexor Digitorum Longus in simple medical language.
  • This article explains Nerve Supply of Flexor Digitorum Longus in simple medical language.
  • This article explains Blood Supply of Flexor Digitorum Longus in simple medical language.
  • This article explains Function of Flexor Digitorum Longus in simple medical language.
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Seek urgent medical care if you notice

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  • Severe symptoms, breathing difficulty, fainting, confusion, or rapidly worsening illness.
  • New weakness, severe pain, high fever, or symptoms after a serious injury.
  • Any symptom that feels urgent, unusual, or unsafe for the patient.
1

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2

See a doctor

Book a professional medical evaluation if symptoms persist, worsen, recur often, affect daily activities, or occur in a high-risk patient.

3

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Use this article to understand possible causes, tests, treatment options, prevention, and questions to ask your clinician.

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Definition

Flexor Digitorum Longus Muscle/The flexor digitorum longus is situated on the tibial side of the leg. At its origin, it is thin and pointed, but it gradually increases in size as it descends. This muscle serves to curl the second, third, fourth, and fifth toes (flexion of phalanges II-V). Flexor digitorum longus is a thin muscle that belongs to the deep posterior muscles of the leg. It runs from the posterior surface of the tibia, across the posterior compartment of the leg to the phalanges of the foot. On its course, the muscle receives functional support from the quadratus Plantae muscle.

Due to its attachments, flexor digitorum longus performs its action in four different joints; talocrural (ankle joint), talocalcaneal (subtalar joint), metatarsophalangeal and interphalangeal joints. The main function of this muscle is the flexion of the foot and toes.

Anatomy of Flexor Digitorum Longus

  • Origin: Posterior surface of the tibia distal to the popliteal line
  • Insertion: Continues distally to split into four individual tendons which insert on the plantar surfaces of the bases of the second through fifth distal phalanges
  • Action: Flex the digits two through five and may aid in plantar flexion of the ankle
  • Blood Supply: Posterior tibial artery
  • Innervation: Tibial nerve

Nerve Supply of Flexor Digitorum Longus

  • Like all muscles in the deep posterior compartment of the leg, flexor digitorum longus muscle is innervated by branches of the tibial nerve (root value L5, S1 and S2) which is a branch of sciatic nerve.

Blood Supply of Flexor Digitorum Longus

  • Flexor digitorum muscle is supplied by branches of the posterior tibial artery, which is a terminal branch of the popliteal artery.
  • The blood from the deep posterior compartment of the leg is drained through posterior tibial veins which empty into the popliteal vein.

Function of Flexor Digitorum Longus

  • Similar to the flexor hallucis longus and tibialis posterior muscles, the flexor digitorum longus muscle functions to plantar flex and invert the foot. The flexor digitorum longus muscle is responsible for the movement and curling of the second, third, fourth and fifth toes.
  • This muscle makes it possible for the toes to grip the surface of floors, which is important when it comes to maintaining postural balance on surfaces that are rough or uneven. The other deep muscles are the flexor hallucis longus and tibialis posterior; the tibialis posterior is the most powerful of these deep muscles. All three muscles are innervated by the tibial nerve which comprises half of the sciatic nerve.
  • As the name suggests, the main function of this muscle is plantarflexion of the foot at the ankle joint and the second to fifth phalanges at the metatarsophalangeal and interphalangeal joints. Plantarflexion is aided by the triceps surae muscle. Due to its attachments and course around the medial malleolus, flexor digitorum longus assists in foot inversion at the subtalar joint.

The actions of flexor digitorum longus are crucial for the gait cycle. When the foot is off the ground, flexor digitorum longus muscle flexes the four lateral toes. This action starts in the distal interphalangeal joints and is followed by flexion in proximal interphalangeal and metatarsophalangeal joints respectively. When the foot is placed on the ground, flexor digitorum longus acts in synergy with the lumbrical and interossei muscles to maintain balance by keeping the toes in firm contact with the ground.

References

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OTC medicine safety

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Doctor to discuss: Doctor / qualified healthcare provider
Tests to discuss with doctor
  • Basic vital signs: temperature, pulse, blood pressure, oxygen level if needed
  • Relevant blood, urine, imaging, or specialist tests only after clinical assessment
Questions to ask
  • What is the most likely cause of my symptoms?
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Emergency warning signs such as chest pain, severe breathing difficulty, sudden weakness, confusion, severe dehydration, major injury, or loss of bladder/bowel control need urgent medical care. Do not wait for online information.

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Care roadmap for: Flexor Digitorum Longus Muscle – Anatomy, Nerve Supply

Use this simple roadmap to understand the next safe steps. It is educational and does not replace examination by a doctor.

Go to emergency care if you notice:
  • Severe or rapidly worsening symptoms
  • Breathing difficulty, chest pain, fainting, confusion, severe weakness, major injury, or severe dehydration
Doctor / service to discuss: Qualified healthcare provider; specialist depends on symptoms and examination.
  1. Step 1

    Check danger signs first

    If danger signs are present, seek emergency care and do not wait for online information.

  2. Step 2

    Record the symptom story

    Write when symptoms started, severity, medicines already taken, allergies, pregnancy status, and test results.

  3. Step 3

    Visit a qualified clinician

    A doctor, nurse, or qualified healthcare provider can examine you and decide which tests or treatment are needed.

  4. Step 4

    Do only useful tests

    Do tests after clinical assessment. Avoid unnecessary tests, random antibiotics, or repeated medicines without diagnosis.

  5. Step 5

    Follow up and return early if worse

    If symptoms worsen, new warning signs appear, or treatment is not helping, return for review quickly.

Rural patient practical tips
  • Take a written symptom diary and all previous prescriptions/test reports.
  • Do not hide medicines already taken, even herbal or over-the-counter medicines.
  • Ask which warning signs mean urgent referral to hospital.

This roadmap is for education. A real diagnosis and treatment plan requires history, examination, and clinical judgment.

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Frequently Asked Questions

Is this article a replacement for a doctor?

No. It is educational content only. Patients should consult a qualified clinician for diagnosis and treatment.

When should I seek urgent care?

Seek urgent care for severe symptoms, rapidly worsening condition, breathing difficulty, severe pain, neurological changes, or any emergency warning sign.

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