Full Answer Section

1. Tongue Positioning and Cupping: The tip and sides of the tongue create a seal against the alveolar ridge (the bony ridge behind the upper teeth), forming a central depression or “cup” on the dorsum of the tongue. The bolus rests within this cup.
2. Bolus Manipulation and Cohesion: The tongue muscles (intrinsic and extrinsic) work to maintain the bolus as a cohesive unit. The tongue may make small movements to ensure the bolus is positioned optimally for transport. Saliva continues to play a role in maintaining bolus consistency and lubrication.
3. Posterior Tongue Movement and Propulsion: The posterior portion of the tongue begins to depress and move backward in a stripping wave-like motion. This action sequentially presses the bolus against the hard palate, creating pressure that propels it towards the pharynx. This posterior movement is a controlled and coordinated action, not a rapid expulsion.
4. Contact with the Faucial Arches: The oral phase is considered complete when the leading edge of the bolus passes the anterior faucial arches (the folds of tissue at the back of the oral cavity, marking the boundary between the oral cavity and the pharynx). This contact triggers the involuntary pharyngeal swallow reflex.

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

The intricate neuromuscular control required for the oral phase makes it susceptible to disruption from various factors:

• Neurological Disorders:
  • Stroke (Cerebrovascular Accident – CVA): Weakness or paralysis of the tongue and facial muscles can impair bolus manipulation, containment, and propulsion. Reduced sensory awareness can also affect bolus control.
  • Traumatic Brain Injury (TBI): Can lead to cognitive deficits affecting the initiation and sequencing of swallowing, as well as motor impairments affecting oral musculature.
  • Cerebral Palsy: Characterized by motor impairments that can affect tongue control, lip closure, and coordination required for bolus formation and transport.
  • Parkinson’s Disease: Rigidity, bradykinesia (slowness of movement), and tremor can affect tongue movement and coordination, leading to difficulties in bolus manipulation and delayed oral transit.
  • Amyotrophic Lateral Sclerosis (ALS): Progressive muscle weakness, including the tongue and facial muscles, directly impairs bolus control and propulsion.
  • Multiple Sclerosis (MS): Can cause a variety of neurological deficits, including weakness, sensory changes, and incoordination affecting the oral phase.
• Structural and Anatomical Abnormalities:
  • Oral Cancer and Surgical Resection: Removal of parts of the tongue, palate, or other oral structures can directly impact the ability to form a seal, manipulate the bolus, and generate the pressure needed for propulsion.
  • Trauma to the Oral Cavity: Lacerations, fractures of the mandible or maxilla, or burns can impair the structural integrity and function of the oral cavity.
  • Cleft Lip and Palate: Can affect the ability to create an adequate oral seal and manipulate the bolus effectively.
  • Dental Issues: Poor dentition, missing teeth, or ill-fitting dentures can impair the oral preparation phase, leading to larger, less cohesive boluses that are harder to control during the oral phase.
• Medical Conditions:
  • Xerostomia (Dry Mouth): Reduced saliva production (due to medications, radiation therapy, or certain medical conditions) can impair bolus formation, cohesion, and lubrication, making oral transit difficult.
  • Infections (e.g., Oral Thrush, Herpes Simplex): Pain and discomfort in the oral cavity can affect normal oral motor movements and bolus manipulation.
  • Aging (Presbyphagia): Natural age-related changes in muscle strength, sensory perception, and coordination can lead to subtle but noticeable changes in the efficiency of the oral phase.
  • Medication Side Effects: Certain medications can cause drowsiness, confusion, or motor impairments that indirectly affect the oral phase.

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

A deficit in the oral phase significantly impacts the subsequent pharyngeal phase of swallowing in several ways:

• Delayed Triggering of the Pharyngeal Swallow Reflex: The pharyngeal swallow reflex is typically triggered when the bolus reaches the anterior faucial arches. Inefficient oral propulsion can lead to a delay in the bolus reaching this trigger point. A delayed trigger increases the risk of the bolus entering the airway before the protective mechanisms of the pharyngeal swallow (e.g., laryngeal elevation and closure, epiglottic inversion) are fully engaged, increasing the risk of aspiration (food or liquid entering the trachea).
• Poor Bolus Control Entering the Pharynx: If the bolus is not cohesive or is propelled posteriorly in an uncoordinated manner, it can enter the pharynx prematurely or in multiple uncontrolled segments. This makes it more difficult for the pharyngeal swallow to effectively clear the bolus, again increasing the risk of aspiration or residue left in the pharynx.
• Increased Risk of Premature Spillage: Weak oral musculature or poor bolus containment can lead to premature spillage of food or liquid into the pharynx before the voluntary oral phase is complete and before the pharyngeal swallow is triggered. This “pre-swallow aspiration” is a significant concern.
• Increased Pharyngeal Residue: Inefficient oral propulsion may leave residue of the bolus in the oral cavity or valleculae (spaces at the base of the tongue) that can then spill into the pharynx after the swallow, leading to post-swallow aspiration.
• Altered Sensory Feedback: Deficits in oral sensation can affect the individual’s awareness of the bolus position and movement, further impacting the coordination and efficiency of both the oral and subsequent pharyngeal phases.

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

Patients with deficits in the oral phase of swallowing may exhibit a variety of symptoms, including:

• Difficulty Chewing: Although primarily related to the oral preparation phase, inefficient chewing can lead to difficulties in bolus formation for the oral phase.
• Difficulty Forming a Bolus: Patients may struggle to manipulate the food in their mouth into a cohesive mass. Food may spread around the oral cavity.
• Drooling or Anterior Loss of Food/Liquid: Weak lip closure or poor bolus containment can result in leakage of saliva, food, or liquid from the mouth.
• Prolonged Oral Transit Time: It takes the patient longer than usual to move the bolus from the front to the back of the mouth.