The tongue is a complex muscular hydrostat that plays a defining role in mastication (chewing) and deglutition (swallowing). Correct positioning of this powerful muscle is directly linked to the proper development of the jaws, the alignment of the teeth, and the maintenance of a healthy airway. Understanding the mechanics of where the tongue should be at rest and during function is central to proper oral posture or myofunction. The forces exerted by the tongue, even at rest, can influence the structure and function of the entire craniofacial system over time.
Tongue Placement During Chewing
During eating, the tongue acts as a coordinated manipulator, constantly positioning the food between the teeth for grinding (mastication). The tongue moves the food bolus laterally and vertically across the molars. It also mixes the food with saliva, which begins chemical digestion and forms a cohesive ball of food called the bolus.
The tongue must remain contained completely within the dental arches while chewing, never pushing outward against the front teeth. The cheeks, aided by the buccinator muscles, collaborate with the tongue to keep the food positioned centrally on the chewing surfaces. This coordination ensures efficient breakdown of the food and prepares the bolus for swallowing.
The Proper Swallowing Sequence
The correct swallow, or mature swallow pattern, is a complex, wave-like motion designed to propel the food bolus backward toward the pharynx. This movement is initiated by the tongue pressing against the alveolar ridge, a bumpy area of tissue located just behind the upper front teeth.
The tongue then executes a sequential movement, often described as a lingual wave, where the front portion pushes up and back against the hard palate. This upward pressure creates a seal and effectively propels the bolus down the throat. The entire process should occur with minimal visible effort from the lips, cheeks, or neck muscles.
A proper swallow involves the tongue pressing firmly against the palate, which prevents the tongue from pushing against the teeth. An incorrect pattern, often called a reverse swallow or tongue thrust, involves the tongue pushing forward or sideways against or between the teeth. Since the average person swallows hundreds of times per day, an incorrect pattern can exert significant, chronic pressure on the teeth and surrounding structures. The correct technique ensures efficient propulsion without interfering with dental alignment.
The Importance of Resting Tongue Posture
Functional movements like chewing and swallowing occupy only a fraction of the day, making the resting tongue posture more impactful on oral health. Proper resting posture dictates that the entire body of the tongue should be suctioned up against the hard palate, filling the oral cavity. The tip of the tongue should lightly rest on the alveolar ridge, the same spot used to initiate a correct swallow.
This high palatal rest position encourages nasal breathing, as it is difficult to maintain the tongue up while breathing through the mouth. For this posture to be maintained, the lips should be gently sealed, and the teeth should be slightly apart, maintaining a small freeway space. The constant, gentle outward force the tongue exerts against the palate during rest promotes the proper development and width of the upper jaw (maxilla).
This balanced muscle activity counters the inward pressure exerted by the cheeks and lips, maintaining the stability of the dental arches. Even a few grams of continuous force from the tongue is enough to influence tooth position and bone structure over time. Maintaining this ideal resting position is a passive, ongoing form of orthodontic support.
Effects of Incorrect Oral Posture
When the tongue habitually rests low in the mouth or pushes forward during swallowing, it can lead to an orofacial myofunctional disorder (OMD). This improper posture removes the supportive pressure from the palate, resulting in a narrower upper jaw. A constricted maxilla often leaves insufficient space for permanent teeth, contributing to dental crowding.
The persistent outward force from a tongue thrusting habit can cause various forms of malocclusion. The most common is an anterior open bite, where the front upper and lower teeth do not overlap when the mouth is closed. Other issues include proclination, where the upper front teeth tilt forward due to repeated pressure. A low-resting tongue is often a symptom or cause of mouth breathing, which is associated with a range of health concerns, including an increased vertical height of the face and a retruded chin.
Incorrect tongue placement can also affect speech, leading to articulation errors such as a frontal lisp, where the tongue pushes against or between the front teeth when producing sounds like /s/ and /z/. Correcting these habitual patterns often requires specialized intervention, such as orofacial myofunctional therapy, to retrain the muscles. The goal is to establish a correct posture that supports long-term oral and facial health.