Posterior compartment of the forearm Posterior compartment of the forearm The posterior compartment of the forearm (or extensor compartment) contains twelve muscles which are chiefly responsible for extension of the wrist and digits, and supination of the forearm. It is separated from the anterior compartment by the interosseous membrane between the radius and ulna. There are generally twelve muscles in the posterior compartment of the forearm, which can be further divided into a superficial, intermediate, and deep layer. Most of the muscles in the superficial and the intermediate layers share a common origin which is the outer part of the elbow, the lateral epicondyle of
Forearm (comics) "the boy". Forearm was also featured in a "What If" issue that asks "What If Magneto Took Over the USA." He is shown as a member of the MLF. In this storyline, Magneto killed Stryfe and coerced the remaining members of MLF to follow him. Forearm was also killed during this reality in an explosion. Forearm (comics) Forearm (Michael McCain) is a fictional mutant villain appearing in American comic books published by Marvel Comics. As a member of the Mutant Liberation Front, Forearm has always been a mainstay on the terrorist group's roster, even staying through leader changes and incarceration.