The lumbrical tendons arise from the FDP tendons in the palm and insert into the radial lateral bands of the finger extensor expansions. Their unique origin from a moving structure (the FDP tendon) means they tighten as the FDP contracts, providing automatic MCP flexion with IP extension as the FDP pulls the origin proximally. This mechanism allows precise control of the intrinsic-plus finger position essential for fine manipulation.
Simultaneous MCP flexion and IP extension (the lumbrical-plus position); fine motor control of finger position
Lumbrical-plus finger is a paradoxical extension deformity that occurs when the finger is asked to flex — the FDP contraction tightens the lumbrical (pulling its origin proximally) which extends the IP joints instead of flexing them. It occurs after FDP tendon repair under excessive tension when the repair site cannot advance as far as the normal FDP excursion, making the lumbrical increasingly taut during FDP contraction.
Paradoxical IP extension during finger flexion attempt from FDP repair under excessive tension making the lumbrical taut, managed by releasing the A1 or A2 pulley to allow more FDP excursion.
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.
