MCQ Physiology Answer 20

Correct Answer: A

The upper esophageal sphincter does not contract when swallowing.

Stages of Swallowing

Difficulty swallowing liquids is usually due to poor muscular control before the swallow. This is the most common cause of dysphagia in individuals with neurologic diseases.

Difficulty swallowing solid food is usually associated with anatomic and physiologic abnormality. For example, an alaryngeal patient has difficulty with posterior tongue movement

Oral Stage
The oral stage is voluntary and requires control of oral structures, including the anterior position of the soft palate. Following mastication, the food is pulled together into a cohesive mass. Next, in a second or less, the tongue propels the bolus posteriorly. The oral stage ends once the material passes the anterior faucial arches at the back of the throat.

This posterior tongue movement and the material passing along the anterior faucial arches help activate the involuntary or reflexive swallow that constitutes the pharyngeal stage.

The reflex is believed to originate in the fauces, soft palate, base of the tongue, and posterior pharyngeal wall. Innervation is primarily from the vagus in the brain stem, but involves cranial nerves IX through XI.

Because these nerves exit the medulla and pass through the jugular foramen together, localized trauma and disease may damage both structures resulting in dysarthria, dysphagia, and dyspnea.

Potential problems -- The oral stage requires adequate chewing, sealing, and transporting of the bolus. Some of the possible difficulties in this stage may arise from lip paresis as well as reductions in buccal tension, tongue elevation and posterior carriage, range of jaw movement, and oral sensitivity.

These may lead to spilling or pocketing of the bolus in lateral sulci, and may delay the swallow reflex. Problems during the oral stage may cause food or liquid to fall into the pharynx and lead to aspiration before the swallow reflex is elicited.

Pharyngeal Stage

This is a reflexive stage that begins with the raising of the hyoid and larynx, and closing of the thyroarytenoid and ventricular
cords to create a velopharyngeal seal.

Next, the epiglottis tilts and the cricopharyn-geus muscle, or superior esophageal sphincter, is relaxed, opening the esophagus.

With the help of accessory muscles, a peristaltic wave moves the bolus through the hypopharynx and into the esophagus in approximately one second.

Potential problems -- Factors that may lead to difficulties during this stage include: Velopharyngeal insufficiency, reduced swallow reflex, poor peristalsis, reduced pharyngeal pressure, and residue in the valleculae and piriform sinuses. Also, there may be restricted elevation of the larynx and an inadequate tilting of the epiglottis as well as incomplete closure of the vocal cords.

Esophageal Stage

This phase begins as the superior esophageal sphincter opens and, propelled by the peristaltic wave contractions that were started in the pharyngeal phase, the bolus passes through the esophagus and inferior esophageal sphincter into the stomach. This stage takes from 8 to 20 seconds.

Potential problems -- The esophageal phase requires an adequate opening of the superior and inferior esophageal sphincters, as well as good peristaltic movement of the bolus into the stomach.

Possible difficulties in this stage include a reduced cricopharyngeal opening, resulting in some material remaining in the pharynx and posing a risk for aspiration after the swallow; and esophageal reflux, in which material returns to the pharynx from the esophagus and poses a risk for aspiration.

Category: Physiology MCQs