Where does the biceps brachii originate (both heads), where does it insert, and what is its primary action?

• A. Origin: the long head from the supraglenoid tubercle of the scapula; the short head from the coracoid process; Insertion: radial tuberosity and bicipital aponeurosis; Primary action: elbow flexion and forearm supination.
• B. Origin: the coracoid process and infraglenoid tubercle; Insertion: olecranon; Actions: elbow extension.
• C. Origin: supraglenoid tubercle only; Insertion: radial head; Actions: shoulder abduction.
• D. Origin: anterior scapular margin; Insertion: bicipital groove; Actions: elbow flexion.

Answer: (A)

The main idea is how the biceps brachii is built and what it does across the elbow and forearm. The muscle has two heads with distinct origins but a common insertion, and its primary job is to flex the elbow and rotate the forearm to turn the palm up (supination).

The correct description has the long head starting at the supraglenoid tubercle of the scapula and the short head starting at the coracoid process. These two heads converge into a tendon that inserts on the radial tuberosity, with a bicipital aponeurosis continuing distally to the forearm fascia. The primary action is elbow flexion paired with forearm supination, especially when the elbow is flexed. The long head also crosses the shoulder joint, so it can assist with shoulder movements, but its main function remains at the elbow and forearm.

The other statements mix up where the muscle originates or inserts or misstate its actions. For example, suggesting insertion at the olecranon and elbow extension describes the triceps rather than the biceps; claiming insertion at the radial head or shoulder abduction conflicts with the biceps’ actual attachments and primary actions.