The primary muscle responsible for extension of the fingers is the extensor digitorum.
The extensor digitorum, also known as the extensor digitorum communis, is located in the posterior forearm. Its main function is to extend (straighten) the four medial fingers (index, middle, ring, and little fingers) at the metacarpophalangeal joints (the knuckles).
Here's a breakdown of the extensor digitorum muscle:
- Location: Posterior compartment of the forearm.
- Action: Extends the metacarpophalangeal joints of the fingers (primarily digits 2-5). It can also assist in wrist extension.
- Innervation: Posterior interosseous nerve, a branch of the radial nerve.
- Other Contributing Muscles: While the extensor digitorum is the primary extensor, other muscles assist in finger extension, including the extensor indicis (for the index finger) and the extensor digiti minimi (for the little finger). These muscles provide independent extension to those specific fingers.
In summary, while other muscles play a role in independent finger extension, the extensor digitorum is the main muscle responsible for extending all four medial fingers.
