The vallecula is a small, anatomical depression located in the throat that serves as a passageway junction in the upper airway. This depression is lined with mucosa and is situated at the root of the tongue, where it transitions into the throat structure. Derived from the Latin word for “little valley,” the vallecula is an integral component of the pharynx, the muscular tube connecting the nasal and oral cavities to the esophagus and larynx. Its specific location and structure give it a significant functional role in the complex process of swallowing.
Anatomy and Location
The vallecula is an anatomical space that exists immediately behind the base of the tongue. It is not a single structure but is typically divided into two bilateral depressions by a central fold of tissue.
The boundaries of this space are formed by several connecting folds of mucous membrane known as the glossoepiglottic folds. The median glossoepiglottic fold runs down the center, dividing the space into the left and right valleculae. On the outer edges, the lateral glossoepiglottic folds help define the perimeter of the depressions as they extend toward the pharyngeal wall.
The vallecula is bordered superiorly by the posterior surface of the tongue’s base and inferiorly by the anterior surface of the epiglottis. The epiglottis is the flexible, leaf-shaped cartilage that acts as a protective flap over the entrance to the larynx. The vallecula is the space created by the reflection of the mucous membrane between the tongue and this flap.
The vallecula is deeply positioned within the oropharynx, making it invisible without specialized instruments. It is not a muscular structure but is closely adjacent to muscles of the tongue and pharynx, which influence its function. The location of the vallecula also makes it a point of rich sensory innervation, receiving nerve supply from the glossopharyngeal nerve (Cranial Nerve IX).
Role in Swallowing Mechanics
The primary physiological function of the vallecula relates to the protection of the airway during the process of deglutition. Before the actual swallow reflex is initiated, the vallecula temporarily collects small amounts of liquid or saliva. This temporary pooling, sometimes referred to as a “spit trap,” helps prevent the swallowing reflex from being triggered, particularly when a person is lying down or asleep.
During the pharyngeal phase of swallowing, the tongue begins to push the food or liquid bolus toward the back of the mouth and throat. As the tongue moves backward and downward, the bolus material fills the vallecula, initiating a cascade of protective movements. At the same time, the muscles connected to the larynx pull it upward and slightly forward.
This upward movement of the larynx is coupled with the action of the tongue, causing the flexible epiglottis to flip backward over the opening of the windpipe. The filling of the vallecula and the movement of the epiglottis work together to ensure the airway is sealed off. The pocket of the vallecula is momentarily flattened out, effectively turning the area into a smooth slide that directs the food or liquid past the closed larynx.
This coordinated action ensures that the ingested material is channeled safely into the esophagus. If the vallecula fails to function correctly, or if the timing of the reflex is impaired, food or liquid may enter the airway, leading to aspiration and potentially causing a cough or choking episode. This protective role is a component of normal, healthy swallowing.
Use in Airway Management Procedures
The vallecula serves as a fundamental anatomical landmark for healthcare professionals performing endotracheal intubation, a procedure used to secure a patient’s airway. This involves inserting an endotracheal tube into the trachea (windpipe) to ensure mechanical ventilation can be delivered. To do this successfully, the practitioner must first achieve a clear, direct view of the vocal cords.
The most common device used for this procedure is a laryngoscope, which has a handle and an illuminated blade. When using the curved Macintosh-style laryngoscope blade, the vallecula is the specific target for blade placement. The operator carefully advances the tip of the curved blade into the vallecula, but not past the epiglottis.
Once the blade tip is correctly seated within the depression, the operator lifts the laryngoscope handle in an upward and outward motion. This indirect lifting action causes the tip of the blade to engage the hyoepiglottic ligament. By pulling on this ligament, the epiglottis is indirectly lifted and moved out of the line of sight.
Lifting the epiglottis exposes the glottis, allowing the practitioner to pass the endotracheal tube into the trachea. This technique contrasts with the use of a straight laryngoscope blade, such as the Miller blade, which is designed to go past the vallecula and directly lift the epiglottis. The ability to visualize the vallecula and use it as a fulcrum is a principle of modern airway management.