The extensor indicis is the only finger extensor with an independent muscle belly dedicated to a single finger, providing the ability to extend the index finger alone while the other fingers remain flexed. This independent extension allows pointing without extending all fingers, an important function in human communication and tool use. As the most expendable forearm extensor, it is the standard donor for EPL tendon transfer after rupture.
| Origin | Posterior surface of the ulna distal to the extensor pollicis longus origin and the adjacent interosseous membrane |
|---|---|
| Insertion | Extensor expansion of the index finger, ulnar to the extensor digitorum tendon |
| Nerve Supply | Posterior interosseous nerve (C7, C8) |
| Blood Supply | Posterior interosseous artery |
| Actions |
|
|---|
Independent index extension from all other fingers is only possible because the EI has its own muscle belly separate from the extensor digitorum, unlike the juncturae tendinum that limit independent ring and little finger extension.
The extensor indicis is the standard tendon transfer donor for EPL rupture repair because it is expendable, its loss produces no functional deficit as the extensor digitorum continues to extend the index finger, and its tendon reaches the thumb with minimal rerouting. Testing EI function by isolating index extension with all other fingers fully flexed (the index test) confirms posterior interosseous nerve integrity.
The EI tendon is palpable on the dorsum of the index finger just ulnar to the extensor digitorum tendon, becoming distinct during isolated index finger extension with the other fingers held flexed.
Surgical use of the expendable extensor indicis tendon to restore EPL function after rupture, providing excellent cosmetic and functional outcomes with no measurable index extension deficit.
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.
