Cartilages of the Larynx
The larynx is the most superior part of the respiratory tract and the voice box of the human body. It surrounds and protects the vocal chords, as well as the entrance to the trachea, preventing food particles or fluids from entering the lungs. The cartilages of the larynx make up its skeleton. Of the nine cartilages all together, three of them are paired and bilaterally symmetrical, while three remain unpaired and specifically placed for accurate function. This article will highlight each cartilage and its most relevant facts, so the reader can gain insight into this complex and detailed anatomical marvel.
This is the largest of the laryngeal cartilages and it is made of two smooth laminae of which the two lower thirds fuse in the midline, while the most superior third remains unfused and creates the laryngeal notch. The thyroid cartilages is the one that makes the well known Adam’s apple due to the laryngeal prominence that is made because of the fused laminae. The cartilaginous superior and inferior horns are created by the projections of the posterior superior and inferior borders of the cartilage respectively. The thyrohyoid membrane connects the entire superior aspect of the cartilage to the hyoid bone.
The epiglottic cartilage which is also known as the epiglottis, or simply the glottis, is an elastic cartilage which looks like a leaf. When oral contents are swallowed, it functions by closing over the laryngeal inlet. It is situated between the hyoid bone and the dorsal part of the tongue anteriorly and the laryngeal inlet posteriorly, while the superior tip is left standing free. The base of the epiglottis is, however, fastened to the thyroid laminae in the midline via the thyroepiglottic ligament. Several membranes run bilaterally between the arytenoid cartilages and the epiglottic cartilages and are quadrangular in shape, so their free corners along with the covering mucosa produce the aryepiglottic fold.
This cartilage is shaped like a signet ring, with the signet-shaped lamina facing posteriorly. It is a complete circle of cartilage and is attached superiorly via the median cricothyroid ligament to the inferior aspect of the thyroid cartilage.The cricotracheal ligament also attaches it to the trachea inferiorly. Its strength and thickness are necessary for holding the upper and lower respiratory tracts together.
The arytenoid cartilages are the only major cartilages to be paired, since the corniculate and cuneiform cartilages are seen to be minor cartilages. They are pyramidal in shape and have three faces. The cricoid lamina articulates with these cartilages on its lateral superior aspect. The three processes of a single arytenoid cartilage include the apex which is most superior, which balances the corniculate cartilage and attaches to the aryepiglottic fold. Also, the vocal process which sits anteriorly and is the posterior attachment of a vocal cord. Finally, the muscular process, which sits laterally and holds the posterior and lateral insertions of the cricoarytenoid muscles.
Corniculate and Cuneiform Cartilages
These minor paired cartilages are seen as nodules in the posterior aryepiglottic folds. The corniculate cartilages attach themselves to the apex of the arytenoid cartilages where the aryepiglottic fold inserts and that is how the nodule-shape in the fold is made. The cuneiform cartilages do not attach themselves to any other cartilages, just muscles and ligaments.