Esophageal Phase

SUMMARY:

According to Nam-Jong (2021), peristalsis, or the movement of the bowels, propels the bolus downward during the esophageal phase. When the swallow is initiated, the lower esophageal sphincter relaxes, and this relaxation continues until the food bolus has been driven into the stomach, when the swallow is completed. The lower esophageal sphincter, in contrast to the upper esophageal sphincter, is not pushed open by extrinsic muscle. Instead, it shuts after the bolus has been swallowed, preventing gastroesophageal reflux from occurring.

The medulla is in charge of controlling this involuntary swallowing reflex, however the cerebral cortex may be responsible for initiating deliberate swallowing.

It is possible that contractions will be necessary for 8-20 seconds in order to force the bolus into the stomach.

The esophageal phase of swallowing is entirely reflexive, and it is not within the control of the individual. As soon as the bolus approaches the esophagus's aperture, the next step starts to unfold. It is carried down the esophagus to the lower esophageal sphincter (LES) by segmental and inferiorly directed peristaltic (wavelike) contraction and gravity, where it is digested after 8–20 seconds of transit time in the stomach.

When the bolus reaches the upper esophageal sphincter (UES) for stomach transit, the cricopharyngeus contracts again, the larynx and soft palate flatten, and breathing resumes. Breathing is only momentarily paused during a regular swallow for a fraction of a second. When a consequence of the increased pressure in the laryngopharynx induced by resuming breathing, food trapped at the laryngopharyngeal entrance is often blown clear and driven to the pharynx as most individuals exhale after swallowing.

PRESSURES OF DEGLUTITION

While you may think of the swallowing process as a series of muscular manipulations of a bolus, it's more accurate to think of it as a series of muscular manipulations of oral, pharyngeal, and esophageal pressures that move the bolus. Because of the open nasal airway, the oral and pharyngeal cavity pressures are brought into balance with the surrounding atmospheric pressure during the oral preparation stage.

At this point, the soft palate tightens and shuts firmly, isolating the oropharynx from the nasal cavity, and the tongue starts to squeeze the bolus posteriorly as the swallow progresses through it. The bolus is propelled toward the oropharynx as a result of the positive pressure caused by the motions of the tongue.

When the tongue makes contact with the posterior oropharynx, the bolus is transferred into the throat with an extra pressure gradient, resulting in a gag reflex. This causes the bolus to get compressed, increasing the pressure and prompting it to go toward the esophagus. Elevation of the larynx results in a lower pressure at the esophageal entrance, and relaxation of the cricopharyngeus contributes to an even greater rise in the superior-inferior pressure gradient at the mouth.

The laryngeal entryway is firmly constricted to prevent conflating deglutition and breathing pressures, allowing the bolus to naturally gravitate toward the location of lower pressure, the esophageal entrance. The cricopharyngeus contracts most strongly during inspiration, preventing esophageal inflation.

DEFICITS DURING THE ESOPHAGEAL PHASE OF SWALLOWING:

Even though speech-language pathologists do not directly treat the diseases related to the esophageal phase, the speech-language pathologist should have a working awareness of these issues.

According to Nam-Jong (2021), impaired esophageal function may cause food and liquid retention after swallowing. An obstruction, motility dysfunction, or a problem with the lower esophageal sphincter opening might cause this retention. He stated that Achalasia may cause diminished or absent gastroesophageal junction relaxation.

GERD is a serious and even fatal condition. You may have felt “heartburn,” but it was really stomach acids refluxing into your esophagus or throat. This allows gastric juices to enter the esophagus in certain people. A weaker or floppy upper sphincter may allow acids to “reflow” into the pyriform sinus, damaging the pharyngeal tissue. It's possible to aspirate if this happens while you're sleeping.

Take for example the case of a client with oral, pharyngeal, and esophageal dysphagia which resulted after cancer irradiation. The pharyngeal dysphagia was effectively managed by enhancing pharyngeal reflexes, and her esophageal reflux was surgically treated. Her surgery to prevent reflux failed, and she had aspiration pneumonia.

A hiatal hernia occurs when the stomach herniates through the esophageal gap. A faulty lower esophageal sphincter allows reflux into the esophagus. Sometimes, a congenital esophageal deformity like stenosis causes severe, life-threatening malnutrition in a neonate. Rare esophageal malformations may cause direct tracheal ingestion.

Nam-Jong (2021) also added the following esophageal phase disorders:

• Esophageal-to-pharyngeal backflow due to esophageal abnormality

• Tracheoesophageal fistula

• Zenker diverticulum - may cause difficulties swallowing and nighttime aspiration of diverticulum leftovers.

• Reflux

Other esophageal wall or exterior structural abnormalities (esophageal webs, rings, strictures; intraluminal blockage from solids) might result in inadequate esophageopharyngeal peristalsis owing to scleroderma or other disorders.

SUMMARY OF DEFICITS AND DISORDERS:

• GERD (Gastroesophageal reflux disease)

  • When gastric juices or acids go superiorly towards the esophagus

  • They experience heartburn or acid burn in their esophagus or chest pains (even though they do not have cardiac problems)

  • Burning sensation cause by the acid from gastric region being refluxed into the esophagus or pharynx

  • Cause: Abnormal or premature relaxation of the gastroesophageal sphincter or the lower esophageal sphincter

• Hiatal hernia

  • Stomach herniates due to malfunction of the lower esophageal sphincter.

  • Herniation - There is a bulging congenital malformation of esophagus such as stenosis

• Disorders

  • Intact, normal esophagus

  • Esophagus that is anastomosing with the trachea (meaning it is opening, and connected to the trachea)

  • Stenosis - The diameter of the esophagus is greatly reduced

  • Discontinuity of the esophagus - It is not connected to the pharynx, or to the stomach

  • Esophageal fusion with the trachea - Part of the esophagus coming from the superior end is connected to the trachea, as well as the inferior end. This will cause problems because bolus will enter the airway. Treatment is surgery

REFERENCES:

Fuller, D. R., Pimentel, J. T., & Peregoy, B. M. (2012). Applied anatomy & physiology for speech-language pathology & audiology. Wolters Kluwer/Lippincott Williams & Wilkins Health.

Nam-Jong, P. (2021). Dysphagia: Practice Essentials, Background, Anatomy. EMedicine, 4(2). https://emedicine.medscape.com/article/2212409-overview#a4

Seikel, J. A., Drumright, D. G., & Seikel, P. (2013). Essentials of anatomy & physiology for communication disorders. Delmar Cengage Learning.