Flexor digitorum accessorius longus is a variant accessory muscle of the deep posterior compartment, present in approximately 6-8% of individuals. It originates in the lower leg and passes through the tarsal tunnel alongside the main flexor tendons, sometimes as a separate muscular belly.
| Origin | Fibula or posterior tibia in the deep posterior compartment, proximal to the flexor digitorum longus |
|---|---|
| Insertion | Joins the flexor digitorum longus tendons in the tarsal tunnel or foot |
| Nerve Supply | Tibial nerve |
| Blood Supply | Posterior tibial artery |
| Actions | Assists toe flexion; functions as an accessory to flexor digitorum longus |
|---|
This accessory muscle is a recognised cause of tarsal tunnel syndrome, as its additional bulk within the tarsal tunnel compresses the tibial nerve during exercise. It appears as an unexpected muscular mass on MRI of the tarsal tunnel in symptomatic patients. Surgical decompression includes excision of the accessory muscle belly to decompress the tunnel.
Not reliably palpable due to deep location within the lower leg and tarsal tunnel.
Tibial nerve compression within the tarsal tunnel from the anomalous flexor digitorum accessorius longus muscle belly, producing medial ankle pain and plantar numbness that worsens with activity.
This website uses cookies to enhance your experience. Some are essential for site functionality, while others help us analyze and improve your usage experience. Please review your options and make your choice.
If you are under 16 years old, please ensure that you have received consent from your parent or guardian for any non-essential cookies.
Your privacy is important to us. You can adjust your cookie settings at any time. For more information about how we use data, please read our privacy policy. You may change your preferences at any time by clicking on the settings button below.
Note that if you choose to disable some types of cookies, it may impact your experience of the site and the services we are able to offer.
Some required resources have been blocked, which can affect third-party services and may cause the site to not function properly.
This website uses cookies to enhance your browsing experience and ensure the site functions properly. By continuing to use this site, you acknowledge and accept our use of cookies.
