Physiology of communication

Full Answer Section

Physiological Steps of the Oral Phase:

The oral phase is initiated once food or liquid (the bolus) has been adequately prepared during the oral preparation phase. This phase is characterized by the controlled movement of the bolus from the oral cavity towards the pharynx. It is a voluntary process, typically lasting approximately one second. The specific steps involved are:

1. Bolus Positioning: The tongue plays a crucial role in positioning the bolus on the dorsum (top surface) of the tongue. The exact location depends on the consistency of the bolus. For solids and thicker liquids, the bolus is often held in the midline of the tongue.
2. Anterior and Lateral Seal: The lips close firmly to create an anterior seal, preventing the bolus from leaking out of the mouth. Simultaneously, the sides of the tongue make contact with the lateral alveolar ridges (the bony ridges behind the upper teeth), forming a lateral seal to prevent the bolus from spilling into the lateral sulci (the spaces between the cheeks and gums).
3. Tongue Elevation and Propulsion: The tip and sides of the tongue maintain contact with the alveolar ridge, while the central portion of the tongue elevates sequentially from anterior to posterior. This upward and backward movement of the tongue creates a stripping wave action, applying pressure to the bolus.
4. Bolus Transit: The pressure generated by the tongue propels the bolus posteriorly along the midline of the tongue towards the faucial arches (the opening to the pharynx).
5. Triggering the Pharyngeal Swallow: The oral phase concludes when the leading edge of the bolus passes the faucial arches (specifically, where the base of the tongue intersects with the ramus of the mandible). This triggers the involuntary pharyngeal phase of swallowing.

Disruptions of the Oral Phase due to Disease, Trauma, or Medical Conditions:

The intricate coordination of muscles and sensory feedback involved in the oral phase makes it susceptible to disruption from various factors:

• Neurological Disorders:

  • Stroke (Cerebrovascular Accident): Weakness or paralysis of the facial muscles and tongue can impair lip closure, lateral seal, and the ability to generate the necessary tongue movements for bolus propulsion.
  • Traumatic Brain Injury (TBI): Can result in cognitive deficits affecting bolus manipulation and initiation of the oral phase, as well as motor impairments.
  • Parkinson's Disease: Rigidity and bradykinesia (slowness of movement) can affect tongue mobility and coordination, leading to difficulty forming and propelling the bolus.
  • Amyotrophic Lateral Sclerosis (ALS): Progressive muscle weakness, including the tongue and facial muscles, severely impacts all aspects of the oral phase.
  • Cerebral Palsy: Can cause motor impairments affecting the muscles of the oral cavity, leading to difficulties with bolus control and propulsion.

• Structural and Anatomical Abnormalities:

  • Oral Cancer and Surgical Resection: Removal of parts of the tongue, lips, or palate can directly impact the ability to form seals and manipulate the bolus effectively.
  • Trauma to the Oral Cavity: Injuries to the tongue, lips, cheeks, or palate (e.g., burns, lacerations) can cause pain and impair normal oral movements.
  • Dental Problems: Missing teeth, poorly fitting dentures, or malocclusion can affect the ability to adequately masticate food during the oral preparation phase, leading to larger bolus sizes that are harder to manage during the oral phase.

• Medical Conditions and Treatments:

  • Xerostomia (Dry Mouth): Reduced saliva production (due to medications, radiation therapy, or medical conditions like Sjögren's syndrome) can impair bolus formation and lubrication, making it difficult for the tongue to propel the bolus smoothly.
  • Medication Side Effects: Certain medications can cause drowsiness, confusion, or motor impairments that indirectly affect the oral phase.
  • Radiation Therapy to the Head and Neck: Can cause mucositis (inflammation of the mucous membranes), fibrosis (scarring), and reduced salivary flow, all of which can disrupt the oral phase.

Impact of Oral Phase Deficits on the Next Phase of Swallowing (Pharyngeal Phase):

A compromised oral phase significantly affects the efficiency and safety of the subsequent pharyngeal phase:

• Delayed Triggering of the Pharyngeal Swallow: If the bolus is not efficiently propelled to the posterior oral cavity, the triggering of the pharyngeal swallow may be delayed or even absent. A delayed swallow increases the risk of aspiration (food or liquid entering the airway) as the airway remains unprotected for a longer duration while the bolus is still in the pharynx.
• Premature Spillage into the Pharynx: Weak lip or tongue seals can lead to premature spillage of the bolus into the pharynx before the pharyngeal swallow is triggered. This also significantly elevates the risk of aspiration, as the airway is not yet closed off.
• Poor Bolus Control in the Pharynx: Inefficient oral propulsion can result in a poorly formed or fragmented bolus entering the pharynx. This makes it harder for the pharyngeal muscles to effectively clear the bolus, potentially leading to pharyngeal residue (food or liquid remaining in the pharynx after the swallow) and subsequent aspiration after the swallow.
• Increased Effort and Fatigue: Individuals with oral phase deficits often need to exert more effort to manipulate and propel the bolus. This can lead to fatigue, especially during longer meals, and may compromise the overall efficiency of the swallow.

Expected Symptoms in a Patient with Possible Deficits of the Oral Phase of Swallowing:

Based on the disruptions described above, several symptoms might be observed in a patient with oral phase swallowing deficits:

• Difficulty Initiating a Swallow: The patient may struggle to start the process of moving the bolus from the mouth towards the throat.
• Labial Leakage (Anterior Spillage): Food or liquid may leak from the lips during chewing or when attempting to propel the bolus.
• Lingual Residue: Food may remain on the tongue after the swallow attempt due to weak or uncoordinated tongue movements.
• Buccal Residue (Lateral Spillage): Food may collect in the cheeks due to poor lateral tongue seal.
• Prolonged Oral Transit Time: It takes the patient longer than normal to move the bolus from the front to the back of the mouth.
• Piecemeal Deglutition: The patient may swallow very small amounts of food or liquid at a time, indicating difficulty managing a larger bolus.
• Complaints of Food "Sticking" in the Mouth: The patient may report a sensation of food not moving smoothly through their oral cavity.
• Coughing or Throat Clearing During or Immediately After Eating/Drinking: This may indicate premature spillage into the pharynx or a delayed swallow, leading to aspiration or penetration (food/liquid entering the larynx but not passing below the vocal folds).
• Wet or Gurgly Vocal Quality After Swallowing: This can be a sign of pharyngeal residue that has entered the larynx.
• Patient Reports of Fatigue During Meals: Increased effort required for oral manipulation and propulsion can lead to early fatigue.

A thorough clinical swallowing evaluation, potentially including instrumental assessments like videofluoroscopic swallow study (VFSS) or fiberoptic endoscopic evaluation of swallowing (FEES), would be necessary to definitively diagnose oral phase deficits and determine the underlying cause and appropriate management strategies. Recognizing these symptoms and understanding the physiological underpinnings of the oral phase are crucial for healthcare professionals, particularly speech-language pathologists, in identifying and addressing swallowing disorders.

Sample Answer

The Oral Phase of Swallowing: Physiology, Disruption, and Clinical Implications

The process of swallowing, also known as deglutition, is a complex sensorimotor act essential for nutrition and hydration. It is conventionally divided into four interconnected phases: oral preparation, oral, pharyngeal, and esophageal. Deficits in any of these phases can lead to dysphagia, or difficulty swallowing, impacting an individual's health and quality of life. This analysis will focus specifically on the oral phase of swallowing, detailing its physiological steps, potential disruptions, consequences of these disruptions on subsequent phases, and observable symptoms.