The Adam's apple is formed by the thyroid cartilage, the largest cartilage of the larynx (voice box). This cartilage is more prominent in males due to the influence of testosterone during puberty, causing it to grow larger and tilt forward, creating the visible neck protrusion. The other options are incorrect: windpipe is the trachea, bronchus carries air to lungs, orbicularis oculi is an eyelid muscle.