Final answer:
The biceps brachii's primary function is to flex the forearm at the elbow, not to extend it. It is a two-headed muscle responsible for flexion of the forearm, supination at the radioulnar joints, and flexing the arm at the shoulder joint. The brachialis and brachioradialis muscles aid in forearm flexion.
Step-by-step explanation:
The statement about the biceps brachii that is not accurate is: C) The primary function of the biceps brachii is to extend the elbow joint. In fact, the primary function of the biceps brachii is the opposite of extension; it is to flex the forearm at the elbow. The biceps brachii is a two-headed muscle that plays a crucial role in the movement of the upper arm and the forearm.
The biceps brachii consists of two parts: the long head and the short head. Both of these heads work together to flex the forearm at the elbow joint, assist in supinating the forearm at the radioulnar joints, and flex the arm at the shoulder joint. Furthermore, the muscle is located in the anterior compartment of the arm which is responsible for the flexion and supination of the forearm. Extension of the elbow joint, on the other hand, is primarily performed by the triceps brachii, which is the antagonist to the biceps brachii.
Adjacent to the biceps brachii is the brachialis muscle, which lies deep and also contributes to the power when flexing the forearm. The brachioradialis is involved in flexing the forearm as well, and it assists in lifting loads either quickly or slowly depending on the force required.