Mechanism of Swallowing, Animation in Child model

Summary

Swallowing, or deglutition, is a complex process involving the coordinated effort of over 20 muscles and neural control across the brain and brainstem. The process is divided into three phases: the voluntary oral phase where food is prepared in the mouth, the involuntary pharyngeal phase that ensures food safely enters the esophagus, and the esophageal phase where peristalsis propels food down the esophagus. Proper coordination of breathing and swallowing is crucial to avoid choking or pulmonary aspiration, highlighting the intricate nature of this essential function.

Takeaways

• 😀 Swallowing (deglutition) is a complex process that involves food passing from the mouth through the pharynx and into the esophagus.
• 😀 The process of swallowing requires precise coordination with breathing since both use the pharynx entrance.
• 😀 Failure to coordinate swallowing and breathing can lead to choking or pulmonary aspiration.
• 😀 Over 20 muscles in the mouth, throat, and esophagus are involved in swallowing, all controlled by various cortical areas and brainstem swallowing centers.
• 😀 The brain communicates with these muscles through several cranial nerves.
• 😀 The swallowing process is divided into three phases: oral (buccal), pharyngeal, and esophageal.
• 😀 The oral phase is voluntary, where food is chewed and formed into a bolus that the tongue pushes to the back of the throat.
• 😀 The pharyngeal phase is involuntary, triggered when tactile receptors in the oropharynx are stimulated by the food bolus.
• 😀 In the pharyngeal phase, the tongue blocks the oral cavity, the soft palate blocks the nasal cavity, and the vocal folds close to protect the airway.
• 😀 The esophageal phase involves the propulsion of the food bolus through the esophagus via peristalsis, and the larynx returns to its original position.

Q & A

What is swallowing, or deglutition, and why is it important?

Swallowing is the process by which food passes from the mouth through the pharynx and into the esophagus. It is important because it requires precise coordination with breathing, as both processes share the same entrance (the pharynx). Failure to coordinate these actions can result in choking or pulmonary aspiration.

How many muscles are involved in the process of swallowing?

Swallowing involves over twenty muscles of the mouth, throat, and esophagus, which work together under the control of several cortical areas and the swallowing centers in the brainstem.

How does the brain control the swallowing process?

The brain controls swallowing through several cortical areas and cranial nerves. These neural pathways coordinate the movements of the muscles involved in swallowing.

What are the three main phases of swallowing?

The three phases of swallowing are the Oral (or Buccal) phase, the Pharyngeal phase, and the Esophageal phase. Each phase has distinct actions and is controlled by different neural mechanisms.

What happens during the oral (buccal) phase of swallowing?

In the oral phase, food is moistened with saliva, chewed, and formed into a food bolus. The tongue then pushes the bolus to the back of the throat (the pharynx), a process under voluntary neural control.

What triggers the pharyngeal phase of swallowing?

The pharyngeal phase is triggered when tactile receptors in the oropharynx are stimulated by the food bolus. This initiates the swallowing reflex, which is involuntary and coordinated by the brainstem.

What steps occur to ensure the food bolus passes safely into the esophagus during the pharyngeal phase?

During the pharyngeal phase, several actions occur: the tongue blocks the oral cavity to prevent food from going back to the mouth, the soft palate blocks entry to the nasal cavity, the vocal folds close to protect the airway, the larynx is pulled up, and the epiglottis flips over to cover the trachea. The upper esophageal sphincter also opens to allow the bolus into the esophagus.

Why is the closure of the vocal folds and the epiglottis flipping over important during swallowing?

The closure of the vocal folds and the epiglottis flipping over are crucial for protecting the airway. These actions prevent food or liquid from entering the lungs, which could lead to choking or pulmonary aspiration, a potentially life-threatening condition.

What happens during the esophageal phase of swallowing?

During the esophageal phase, the food bolus is propelled down the esophagus by peristalsis, a wave of muscular contractions that push the bolus ahead. The larynx also returns to its original position at the end of this phase.

How is the coordination between swallowing and breathing managed?

The coordination between swallowing and breathing is managed by the brainstem, which ensures that both actions do not interfere with each other. The brainstem controls the timing of the pharyngeal and esophageal phases to prevent aspiration or choking while breathing.