Three Phases of Swallowing in Infants

Although many adults take swallowing for granted, it is actually a complex process that requires muscular coordination and development. As early as 15 weeks gestation, fetuses begin to suck. The characteristic back-and-forth movement of the tongue becomes more pronounced by the 18th week. Sucking is necessary for the intake of the liquid the infant will swallow.

Oral

• The first phase of swallowing is the oral phase. In this phase, an infant uses his lips, palate and tongue to create suction. After sucking the fluid, he forms it into a bolus, or rounded mass. Young infants make quite simple movements with the tongue; but at the age of three months, infants begin to be able to move boluses, even those that are more solid, with their tongues.

Pharyngeal

• The second phase of swallowing, the pharyngeal phase, is involuntary. When the bolus comes into contact with the pharyngeal wall, a series of events begins. First, the pharynx and the soft palate close off the nasal cavity. Then, the muscles in the pharynx contract, sending the bolus towards the esophagus. At the same time, breathing stops and the vocal cords close in order to prevent aspiration of the bolus. Researchers have observed pharyngeal swallowing in fetuses at 10 weeks gestation.

Esophageal

• Like the second phase, the third phase of swallowing -- the esophageal phase -- is involuntary. In this phase, the bolus moves to the stomach.

Dysphagia

• Dysphagia refers to any abnormality in swallowing. Most commonly found in premature infants, dysphagia results from weak sucking and poor coordination of the "suck-swallow-breathe rhythm," described by Dr. Lisa B. Zaoutis. If your infant has problems swallowing, see your pediatrician immediately in order to prevent aspiration and/or malnutrition.