Normal Swallow
The human swallow is a complex, intricately orchestrated process that results from a careful coordination of actions involving the brain, nerves, and muscles of the mouth, throat, and esophagus (Saint Joseph’s Medical Services, 2006).
The swallowing process begins with the first bite or sip that is placed into the mouth. The lips create an adequate labial seal to prevent liquids and solids from escaping. Jaw and tongue muscles coordinate together and work to successfully masticate (chew) all solids and liquids in the mouth. Chewing works to reduce food particles to a size that is easy to swallow. The mouth then releases saliva which adds digestive enzymes, water, and mucus that help to chemically reduce food particles even further, moisten them for taste, and lubricate them for easy swallowing. This new mixture of masticated food, saliva and liquid is termed bolus. (Encyclopedia Britannica, n.d.)
The tongue makes a crucial contribution to the processes of swallowing and bolus formation. Throughout the oral and pharyngeal phases, the tongue moves the bolus from the tongue to the teeth for mastication, then gathers it at the midline in order to strip it against the hard palate, where it is then propelled through the oral cavity, the oropharynx, and pharynx toward the esophagus. Indeed, other structures contribute to oral and pharyngeal bolus flow, however the tongue provides the major propulsive force (Robbins et al., 2005).
Furthermore, the tongue plays a critical role in creating a channel in which the bolus can flow by generating a rostro-caudal pressure pattern that efficiently transports the bolus through the oropharynx and into the esophagus. (Steele, Lieshout, 2009) The extrinsic muscles of the tongue are believed to govern the position of the tongue within the oropharyngeal cavity, whereas a complex array of intrinsic muscles (oriented in longitudinal, vertical, and transverse directions) support alterations in the shape of the tongue (Napadow, Chen, et al, 1999).
Impairment to the tongue function could have multiple adverse affects on swallowing. Reduced tongue function may directly lead to reduced ability to manipulate a bolus for mastication, gather it after mastication and transport it through the upper digestive tract (Youmans,et al, 2007).
Sensory receptors in the mouth allow the person to taste and perceive where this newly formed bolus is. The tongue then works to efficiently control and move the masticated bolus deeper into the mouth triggering a swallowing reflex. After the tongue has cradled and transferd the bolus from the mouth into the throat (pharynx), the brain receives sensory information that instructs the muscles of the neck and throat to go into motion in order to begin the pharyngeal aspect of the swallow (Saint Josephs’s Medical Services, 2006.)
The swallowing process begins with the first bite or sip that is placed into the mouth. The lips create an adequate labial seal to prevent liquids and solids from escaping. Jaw and tongue muscles coordinate together and work to successfully masticate (chew) all solids and liquids in the mouth. Chewing works to reduce food particles to a size that is easy to swallow. The mouth then releases saliva which adds digestive enzymes, water, and mucus that help to chemically reduce food particles even further, moisten them for taste, and lubricate them for easy swallowing. This new mixture of masticated food, saliva and liquid is termed bolus. (Encyclopedia Britannica, n.d.)
The tongue makes a crucial contribution to the processes of swallowing and bolus formation. Throughout the oral and pharyngeal phases, the tongue moves the bolus from the tongue to the teeth for mastication, then gathers it at the midline in order to strip it against the hard palate, where it is then propelled through the oral cavity, the oropharynx, and pharynx toward the esophagus. Indeed, other structures contribute to oral and pharyngeal bolus flow, however the tongue provides the major propulsive force (Robbins et al., 2005).
Furthermore, the tongue plays a critical role in creating a channel in which the bolus can flow by generating a rostro-caudal pressure pattern that efficiently transports the bolus through the oropharynx and into the esophagus. (Steele, Lieshout, 2009) The extrinsic muscles of the tongue are believed to govern the position of the tongue within the oropharyngeal cavity, whereas a complex array of intrinsic muscles (oriented in longitudinal, vertical, and transverse directions) support alterations in the shape of the tongue (Napadow, Chen, et al, 1999).
Impairment to the tongue function could have multiple adverse affects on swallowing. Reduced tongue function may directly lead to reduced ability to manipulate a bolus for mastication, gather it after mastication and transport it through the upper digestive tract (Youmans,et al, 2007).
Sensory receptors in the mouth allow the person to taste and perceive where this newly formed bolus is. The tongue then works to efficiently control and move the masticated bolus deeper into the mouth triggering a swallowing reflex. After the tongue has cradled and transferd the bolus from the mouth into the throat (pharynx), the brain receives sensory information that instructs the muscles of the neck and throat to go into motion in order to begin the pharyngeal aspect of the swallow (Saint Josephs’s Medical Services, 2006.)
