Final answer:
Muscles that move the forearm and do not promote pronation or supination typically insert on the humerus, and the biceps brachii, brachialis, and brachioradialis are three such muscles. While these muscles are mainly involved in forearm flexion, the biceps brachii also has the capability to supinate.
Step-by-step explanation:
The question pertains to the anatomy of the forearm, specifically to the insertion point of muscles that move the forearm without causing pronation or supination. In this context, the muscles that do not contribute to pronation or supination are typically those that insert on the humerus.
Three muscles that are involved in moving the forearm and inserting onto the humerus are the biceps brachii, brachialis, and brachioradialis. All three muscles are primarily responsible for the flexion of the forearm. The biceps brachii and brachialis do not specifically contribute to pronation or supination of the forearm; however, the biceps brachii can supinate the forearm when the arm is already in supination or neutral. Meanwhile, the brachioradialis is capable of flexing the forearm more quickly or assisting in lifting a load slowly, irrespective of the forearm's pronation or supination state.