Flexor Hallucis Longus (FHL)

Authors
Affiliations

Nate Yomogida, B.S., SPT

Doctor of Physical Therapy

B.S. in Kinesiology

Chloë Kerstein, B.S., SPT

Doctor of Physical Therapy

B.A. in Neuroscience

Figure 1: Muscles of the lower leg
Figure 2: Superficial posterior leg muscles

Deep posterior leg muscles2

Deep posterior leg muscles

The Mucous sheaths of the tendons around the ankle (medial view)2

The Mucous sheaths of the tendons around the ankle (medial view)

1st layer of the plantar foot2

1st layer of the plantar foot

2nd layer of the plantar foot2

2nd layer of the plantar foot

3rd layer of the plantar foot2

3rd layer of the plantar foot
Reading list
  • Ch69 Long toe flexor muscles of the foot
  • Neuman
  • MMT

Overview

Origin

  • Fibula (posterior distal two thirds)
  • IO membrane (adjacent)

Insertion

1st distal phalanx (base)

Innervation

Tibial N. (L5, S1, S2)

Action

  • TCJ: PF
  • STJ: INV
  • MTP and IP 1st toe: Flexion

The posterior tibialis and flexor hallucis longus also improves the stability of ankle joint by creating a dynamic pinch between the malleoli, which improves joint contact during plantarflexio.

The FHL also plays a role in calcaneal frontal plane stabilization. Although it does not insert on the calcaneus, the FHL tendon “hooks” onto the calcaneus in the sustentaculum tali allowing it to exert a force upon the calcaneus. The FHL tendon can control and prevent excessive calcaneal varus/adduction.

MMT

“The FHB VIDEO and FHL muscles VIDEO produce MTP joint flexion and IP joint flexion. The foot is maintained in midposition. The first metatarsal is stabilized, and resistance is applied beneath the proximal and distal phalanx of the great toe into toe extension.”

Pails & Rails

P.A.I.L.’s

  • Plantarflexion
  • Inversion
  • 1st MTP/IP flexion

R.A.I.L.’s

  • Dorsiflexion
  • Eversion
  • 1st toe MTP/IP extension

Stretch

References

1.
Betts JG, Blaker W. Anatomy and Physiology. 2nd ed. OpenStax; 2022. https://openstax.org/details/books/anatomy-and-physiology-2e/?Book%20details
2.
Gray H. Anatomy of the Human Body. 20th ed. (Lewis WH, ed.). Lea & Febiger; 1918. https://www.bartleby.com/107/
3.
Donnelly JM, Simons DG, eds. Travell, Simons & Simons’ Myofascial Pain and Dysfunction: The Trigger Point Manual. Third edition. Wolters Kluwer Health; 2019.
4.
Neumann DA, Kelly ER, Kiefer CL, Martens K, Grosz CM. Kinesiology of the Musculoskeletal System: Foundations for Rehabilitation. 3rd ed. Elsevier; 2017.
5.
Weinstock D. NeuroKinetic Therapy: An Innovative Approach to Manual Muscle Testing. North Atlantic Books; 2010.
6.
Gilroy AM, MacPherson BR, Wikenheiser JC, Voll MM, Wesker K, Schünke M, eds. Atlas of Anatomy. 4th ed. Thieme; 2020.
7.
Jones B. B Project Foundations. b Project; 2025.
8.
Dutton M. Dutton’s Orthopaedic Examination, Evaluation, and Intervention. 5th ed. McGraw Hill Education; 2020.

Citation

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