We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What is the Flexor Hallucis Longus?

By Shelby Miller
Updated May 17, 2024
Our promise to you
WiseGeek is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At WiseGeek, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject-matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

The flexor hallucis longus is a muscle of the posterior compartment of the lower leg. Situated deep in the calf alongside the flexor digitorum longus and the tibialis posterior, it is responsible for flexing or curling the big toe. It fairly centrally located on the back of the leg beneath the larger gastrocnemius and soleus muscles of the calf, though it is nearer to the lateral or fibula side of the leg, with its tendon crossing the ankle joint and running beneath the foot to the big toe. As such, this muscle is involved not only in flexing the big toe, known as the hallux, but of the ankle as well.

Originating about a third of the way down the posterior or rear aspect of the fibula bone, the flexor hallucis longus also finds its origins on the interosseous membrane, which divides the leg into its anterior and posterior compartments. Additionally, it arises from several fibrous tissues encasing nearby muscles, such as the fascia enveloping the tibialis posterior muscle situated just above in the calf. All of these fibers descend and converge to form a tendon. Like those of the flexor digitorum longus and tibialis posterior, this is a fairly large tendon that runs along most of the length of the muscle and then, after the muscle fibers taper off, crosses the ankle.

The tendon of the flexor hallucis longus passes obliquely behind the bottom of the tibia bone on the inner side of the ankle. It then runs between the talus bone of the ankle and, below it, the calcaneus or heel bone via a niche called the sustentaculum tali. Finally, it crosses the underside of the foot alongside the tendon of the flexor digitorum longus and attaches to the base of the distal phalanx of the big toe, the last bone in the hallux. This insertion point allows the flexor hallucis longus to act not only on the distal interphalangeal joint, or the last joint in the toe, but also on the metatarsophalangeal joint, the second joint in the toe, pulling downward on the distal phalanx to curl the entire toe.

In addition to this muscle’s action at the big toe, it is involved in plantarflexion of the entire foot at the ankle. Primarily the responsibility of the larger gastrocnemius and soleus muscles, plantarflexion is the action of pointing the foot downward at the ankle as seen in a dancer pointing her toes. The flexor hallucis longus, bigger and stronger than the adjacent tibialis posterior and flexor digitorum muscles, both of which also support ankle plantarflexion, is a secondary agent of this joint action.

WiseGeek is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Discussion Comments
WiseGeek, in your inbox

Our latest articles, guides, and more, delivered daily.

WiseGeek, in your inbox

Our latest articles, guides, and more, delivered daily.