Final answer:
The cricoid cartilage is involved in the formation of the lower end of the larynx, forming a ring structure below the thyroid cartilage and attaching to the trachea.
Step-by-step explanation:
The cartilage involved in the formation of the lower end of the larynx is the cricoid cartilage. This cartilage forms a ring structure, differentiating it from the other cartilage pieces of the larynx. The cricoid cartilage has a wide posterior region and a thinner anterior region, being inferior to the thyroid cartilage, and it attaches to the trachea. Whereas the thyroid cartilage includes the laryngeal prominence or "Adam's apple" and is the largest of the larynx cartilages; the cuneiform and arytenoid cartilages are smaller and involved with the vocal cords and muscles that help move the vocal cords to produce speech.