What Muscles Does the Bicep Curl Work?

The biceps curl is an exercise for the elbow flexors, which comprise the biceps brachii, brachialis and brachioradialis. You can emphasize each of these muscles by using a variety of grips. It is best to do biceps curls using dumbbells to ensure the elbow flexors of each arm are being worked to the same extent. Also, when you use dumbbells, it is best you do the biceps curls unilaterally, meaning one side at a time. By doing so, you can focus on one side at a time and better stimulate the muscles.

Biceps Brachii

The biceps brachii is a two-headed muscle group that is made up of an inner short head and an outer long head, both of which are located at the front of the arm. The short head originates at the corocoid process of the scapula, or shoulder blade. The long head originates at the supraglenoid tuberosity of the scapula. Both heads insert at the tuberosity of the radius, or inner forearm bone, and at the lacertus fibrosus of the fascia of the forearm. The biceps brachii acts to flex the elbow and supinate the forearm. You can emphasize the biceps brachii by utilizing a supinated, or underhand, grip while doing the biceps curl.

Brachialis

The brachialis is a muscle located underneath the lower part of the biceps brachii. This muscle originates at the distal half of the anterior humerus, or arm bone, and inserts at the coronoid process and the tuberosity of the ulna, or outer forearm bone. The brachialis only has one function, and that is elbow flexion. Emphasize this muscle by using a pronated, or overhand, grip during the biceps curl.

Brachioradialis

The brachioradialis muscle is located at the outer side of the lower arm and forearm. It originates at the lateral condyle of the humerus and inserts at the lateral distal surface of the radius. The brachioradialis also has only a single function of elbow flexion. Emphasize this muscle by utilizing a semi-pronated grip while doing the biceps curl.

Stabilizers

Several stabilizers help fixate the shoulders, scapula, and wrists during the biceps curl. The anterior deltoid stabilizes the shoulders. If cheating repetitions are performed, in which the shoulder is being flexed to raise the arm upwards, then the anterior deltoid acts as an assisting muscle. The superior trapezius, intermediate trapezius, and levator scapulae stabilize the scapula. The wrist flexors and wrist extensors stabilize the wrist.