<prompt> Extension at MCP joint is byExtensor DigitorumDorsal InterosseiPalmar InterosseiLumbricals  <response>: 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. 