What muscle group would primarily flex the elbow?

The biceps brachii is the primary muscle group responsible for flexing the elbow. This muscle, located in the upper arm, has two heads – the long head and the short head – that originate from the shoulder and insert into the radius in the forearm. When the biceps contract, they pull the forearm up towards the shoulder, thereby flexing the elbow joint.

In contrast, the triceps are primarily involved in extending the elbow, and they work in opposition to the biceps. The forearm extensors and wrist flexors also do not contribute to elbow flexion, as they are primarily responsible for extending the wrist and flexing the wrist, respectively. Therefore, the biceps is the muscle group specifically targeted for the action of elbow flexion.