Cricoid has a signet ring shape and is the only cailage forming a complete ring. Its posterior pa is expanded to form a Lamina while anteriorly it is narrow forming an Arch. Whereas in thyroid-the two alae meet anteriorly forming an angle 90 degrees in males & 120 degrees in females. Cuneiform is rod-shaped and Arytenoid is pyramidal in shape. Ref: Textbook of diseases of ENT, PL Dhingra, 7th edition, pg no. 319