Which of the following cartilage encircles the larynx-

Ans. is 'a' i.e., Cricoid o Cricoid cartilage is the only cartilage that forms a complete ring.Laryngeal cartilagesThyroid (unpaired)o It is the largest of all laryngeal cartilages. It is 'V' shaped with right and left lamina. Both laminae (alae) meet anteriorly forming an angle of 90deg in males and 120deg in females and forms laryngeal prominence. Vocal cords are attached to the middle of thyroid angle. Upper border of thyroid cartilage lies at C3-C4 junction (at upper border of O). Thyroid cartilage itself lies at C4-C5 level.Cricoid (unpaired)o It is the only cartilage forming a complete ring, therefore is shaped like a ring. It articulates with arytenoid cartilage to form cricoarytenoid joint, a type of synovial joint. It lies at the level of C6 vertebra.Epiglottis (unpaired)o It is leaf-shaped elastic cartilage (in adults). It is omega shaped in children. It forms the anterior wall of laryngeal inlet. It lies above glottis.Arytenoid cartilage (paired)o Each Arytenoid cartilage is pyramidal in shape. Base articulates with cricoid cartilage, and apex supports the comiculate cartilage. A vocal process directed anteriorly and gives attachement to vocal cord. A muscular process directed laterally and gives attachment to intrinsic laryngeal muscles.Corniculate cartilage (of Santorini) : Pairedo Articulates writh apex of Arytenoid cartilageCuneiform cartilage (of Wrisberg) : Pairedo Situated in aryepiglottic fold in front of comiculate cartilage.