Anterior compartment of forearm muscles: second layer
The second layer (the deepest part of the superficial layer) of the anterior compartment of the forearm contains only one muscle - the flexor digitorum superficialis. It is a flat and prominent muscle that stretches between the humerus, ulna, radius and the phalanges. It is the largest muscle of the anterior forearm muscle group. This muscle is composed of two heads - humeroulnar and radial.