The second dorsal interosseous (DAB: Dorsal ABducts) abducts the middle finger toward the index finger axis, which is the first radial deviation from the middle finger's anatomical position. It is the only dorsal interosseous that abducts from both sides — the middle finger has both a second (radial) and third (ulnar) dorsal interosseous providing bilateral abduction.
| Origin | Adjacent sides of the second and third metacarpals (bipennate) |
|---|---|
| Insertion | Radial base of the proximal phalanx of the middle finger and extensor hood |
| Nerve Supply | Deep branch of the ulnar nerve (C8, T1) |
| Blood Supply | Second dorsal metacarpal artery |
| Actions | Abducts the middle finger radially (toward the index finger); Flexes the MCP and extends the IP joints of the middle finger |
|---|
The second dorsal interosseous is assessed in ulnar nerve palsy by resisted index-middle finger spreading (radial deviation of the middle finger). Its atrophy produces the characteristic dorsal hand guttering between the second and third metacarpals. The second DI belly is also the site of targeted botulinum toxin injection for dystonic middle finger posturing in writer's cramp.
Palpated on the dorsal hand between the second and third metacarpals during resisted middle finger radial abduction.
Visible wasting of the second dorsal interosseous from ulnar nerve palsy producing a hollow between the second and third metacarpals, one of the most visible signs of intrinsic hand muscle denervation.
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.
