Extension at MCP joint is by
(A) Extensor Digitorum # Extensor digitorum muscle actions include Extension of interphalangeal, metacarpophalangeal and wrist joints.> All Palmar interossei adduct the digit to which they are attached towards the middle finger + flex the digit at MCP joint & extend IP joints.> All Dorsal interossei abduct the digits away from the line of the middle finger + flex the digit at MCP joint & extend IP joints.> Lumbrical muscles flex the metacarpophalangeal joints, and extend the interphalangeal joints of the digit into which they are inserted.
Extensor Digitorum
Dorsal Interossei
Palmar Interossei
Lumbricals
Misc.