The larynx, commonly known as the voice box, is located in the anterior neck and plays a part in both the respiratory system and sound production. This structure channels air and prevents foreign material from entering the lungs. The larynx contains an internal cavity structurally divided into three major regions.
The laryngeal vestibule is the uppermost chamber within this internal cavity. It serves as the primary entranceway or funnel-shaped space at the top of the larynx.
The Larynx as the Context
The larynx is situated below the pharynx (throat) and above the trachea (windpipe), typically spanning the C3 to C6 vertebral levels in adults. Its primary purpose is to regulate airflow into the lungs and safeguard the lower respiratory tract. It achieves this with a framework made of nine cartilages.
The largest structures are the thyroid cartilage (Adam’s apple) and the ring-shaped cricoid cartilage at the base. These cartilages provide the structural support necessary for the laryngeal muscles to operate. Their positioning and movement allow the larynx to perform functions such as voice production, coughing, and controlling air passage.
The internal chamber of the larynx is organized into a series of compartments, not a single open tube. These compartments manage the flow of air and the movement of structures responsible for sound. The laryngeal vestibule is the uppermost of these internal spaces, sitting within the supraglottic region.
Pinpointing the Laryngeal Vestibule
The laryngeal vestibule is a wide, triangular space located entirely above the true vocal cords. It is defined by the anatomical structures that form its boundaries. The vestibule begins at the laryngeal inlet, the opening that connects the pharynx to the larynx.
The superior boundary is formed by the epiglottis, a leaf-shaped piece of cartilage projecting upward at the front. Extending backward from the sides of the epiglottis are the aryepiglottic folds, which form the lateral walls of the vestibule. These folds contain small cartilages and muscle fibers, defining the entryway into the larynx.
The inferior limit is demarcated by the vestibular folds, a pair of shelf-like structures often called the false vocal cords. These folds project inward from the side walls of the larynx. The space between the two vestibular folds is called the rima vestibuli, a triangular opening through which air must pass.
This arrangement means the vestibule acts as a wide entry hall before the airway narrows considerably. Air enters the larynx through the inlet, moves through the vestibule, and then passes the rima vestibuli. Its position high in the laryngeal cavity places it directly in the path of anything attempting to enter the trachea.
The Protective Role of the Vestibular Folds
The vestibular folds, which define the lower boundary of the vestibule, primarily protect the airway. They are thick folds of mucous membrane enclosing the vestibular ligament. Unlike the true vocal cords situated below them, these folds lack the specialized structure for regular sound production.
During swallowing (deglutition), these folds rapidly adduct, or close, across the airway. This action works alongside the downward movement of the epiglottis to seal the entrance to the trachea. The closure prevents food, liquid, or saliva from passing through the vestibule and into the lungs, an event known as aspiration.
The vestibular folds function as a backup mechanism to the epiglottis, providing extra defense for the lower respiratory tract. Their protective role is paramount, while the true vocal cords are responsible for phonation by vibrating as air passes through them. Although the folds may be involved in sound production in specific contexts, their primary purpose is maintaining airway integrity.