The epiglottis serves as a flexible lid for the windpipe which closes only while swallowing, and remains upright at other times. Thus, it prevents food particles and liquids from entering the larynx and trachea.
The oral cavity is connected to the openings of both, the windpipe and the food pipe present in the throat. If both the passages remain open at all times, the food swallowed can easily enter the windpipe. Hence, a mechanism is necessary to prevent food particles from entering the windpipe. The malfunctioning of this mechanism can lead to respiratory blockage, choking, coughing and may even lead to death. The detailed position of epiglottis with respect to the laryngeal structure, as well as its function has been explained below.
Structure and Location
The major structures present in our throat are, pharynx, larynx (voice box), esophagus (food pipe) and trachea (windpipe). The larynx is attached to, and opens in to the trachea or windpipe. It is supported by a set of three paired, and three unpaired cartilages. Epiglottis, thyroid cartilage and cricoid cartilage are the three unpaired cartilages, whereas, arytenoid, corniculate and cuneiform cartilages are the paired ones. These cartilages are held together by ligaments and supporting membranes. A horseshoe-shaped bone called the hyoid bone is present superior to the larynx. It is attached to the mandible, and provides support to the larynx.
While swallowing, muscular action results in an upward movement of larynx. Two sets of muscles, namely intrinsic and extrinsic, are responsible for laryngeal movements. The intrinsic muscles are involved in the movement of vocal cords and voice generation. The extrinsic muscles, are the ones involved in the upward and downward movement of the entire laryngeal structure as well as the downward folding of epiglottis.
During normal activities, the epiglottis is present in an upright position. This position is supported by an elastic cartilage that is attached to the thyroid cartilage of larynx. Being in this position, it allows air to flow freely through the larynx into the trachea and lungs.
During the process of swallowing, as soon as the bolus reaches the pharynx, it triggers the contraction of extrinsic muscles. As a result, the entire larynx moves upwards. Due to this shift, the epiglottis comes in contact with the base of the tongue, and gets lowered to block the glottis.
The food bolus, in turn, gets directed to the esophagus, which triggers the relaxation of the extrinsic muscles. The epiglottis then returns to its upright position, and the larynx opens again, thus completing the cycle.
Epiglottis is one of the supporting cartilages that are attached to the larynx and functions as a flexible lid for the windpipe. Along with the larynx and extrinsic muscles, it provides one of the many crucial mechanisms to ensure a smooth functioning of the digestive and respiratory systems.