Sunday, March 15, 2015
Laryngeal cavities
The mucous membrane of the larynx lines the cavity and is covered with ciliated columnar epithelium.
There are many mucous glands contained within the mucous membrane, and they are especially numerous in the saccules. Here, the secretion pours down onto the upper surface of the vocal folds and lubricates them during phonation.
The cavity of the larynx extends from the inlet to the lower border of the cricoid cartilage. It can be divided into three parts: (1) the upper part, or vestibule; (2) the middle part; and (3) the lower part.
1- Entrance is aditus larynges (The upper part):
- The vestibule of the larynx extends from the inlet to the vestibular folds. The latter are two thick folds of mucous membrane that cover the vestibular ligaments.
- The vestibule has an anterior, posterior, and lateral wall. The anterior wall is formed by the posterior surface of the epiglottis, which is covered by mucous membrane. The posterior wall is formed by the arytenoid cartilages and the interarytenoid fold of mucous membrane, containing the transverse arytenoid muscle. The lateral walls are formed by the aryepiglottic folds, which contain the aryepiglottic muscle.
- Below, the vestibule is narrowed by the pink vestibular folds, which project medially.
- The rima vestibuli is the gap between the vestibular folds.
- The vestibular ligament, which lies within each vestibular fold, is the thickened lower edge of the quadrangular membrane.
- The ligament stretches from the thyroid cartilage to the side of the arytenoid cartilage.
2 The middle part of the larynx
- It extends from the level of the vestibular folds to the level of the vocal folds. The vocal folds are white in color and contain the vocal ligaments. Each vocal ligament is the thickened upper edge of the cricothyroid ligament. It stretches from the thyroid cartilage in front to the vocal process of the arytenoid cartilage behind.
- The rima glottidis is the gap between the vocal folds in front and the vocal processes of the arytenoid cartilages behind.
- Between the vestibular and vocal folds on each side is a small recess, called the sinus of the larynx. It is lined with mucous membrane, and from it, a small diverticulum, called the saccule of the larynx, passes upward between the vestibular fold and the thyroid cartilage.
3- The lower part of the larynx
- It extends from the level of the vocal folds to the lower border of the cricoid cartilage.
- Its walls are formed by the inner surface of the cricothyroid ligament and the cricoid cartilage.
