Normal Swallowing in Adults Flashcards
Big Picture: 4 Stages of Normal Swallow
- Oral preparation
¥ Food is masticated in preparation for transfer - Oral (transport)
¥ Transfer food from the mouth to the oropharynx - Pharyngeal
¥ Food is transported away from the oropharynx into upper esophagus - Esophageal
¥ Food is transported from the esophagus to the stomach
Oral preparatory
the act of taking food, chewing it, mixing it with saliva, and forming it into a bolus
Oral transport
controlling the bolus and transporting it to the back of the mouth
Pharyngeal stage
¥ initiating the swallow reflex in a timely manner which is normally 1 second (or less)
¥ food is transported away from the oropharynx into upper esophagus
Esophageal stage
the food enters the esophagus, the passageway to the stomach
Stage 1: Oral Preparation Phase, Function
Function: • Mastication • Bolus formation • Bolus maintenance
Stage 1: Oral Prep & Voluntary Mastication
Voluntary control • Close lips, good buccal tension • Velum lowered for nasal breathing • Lingual-‐velar seal • Mastication • Lateral/rotary jaw/tongue movement (chewing action)
Stage 2: Oral Transport Phase
• Starts when tongue begins to propel the bolus posteriorly • Tongue Tip and sides to the alveolar ridge • Velum elevates, tongue base drops • Propels bolus upward and backward • Oral phase ends when bolus reaches ramus of mandible
When is the Pharyngeal Phase Triggered?
Sometime between the ant. faucial arches to the line of the ramus of the mandible
TRIGGERING the pharyngeal phase:
“Voluntary” initiation of a swallow
Rapid, no delaY (1-1.5 SEC)
Abnormal if oral transport
+ delay > 2 seconds
PERSONS OVER 60 YRS MAY 0.3 seconds longer
Trigger points may differ across ages
-Young adults: ant. faucial pillars
-Older adults: middle of the tongue base
Infants: valleculae
How is the Pharyngeal Phase Triggered?
Sensory input from the oral cavity, tonsils, soft palate, and post pharyngeal (CN IX & X)
Posterior tongue movement
HYPOTHESIZED: a sensory recognition center in the lower brainstem (medulla; CPG) decodes sensory info to the nucleus ambiguous, which initiates the motor response for the pharyngeal swallow.
Stage 3: Pharyngeal Phase
• Involuntary
• (however, it requires “voluntary” initiation of a swallow to trigger the pharyngeal phase) • (once it is triggered) Lasts 1 second or less Velum elevates (VP port closure) • Base of tongue retraction and contact with the posterior pharyngeal wall
- Hyoid bone and larynx elevate and move anteriorly
- Upward + forward
Stage 3: Pharyngeal Phase (Involuntary)
Airway closure at 3 levels (respiration apnea/stops)
Epiglottis
¥ Epiglottic inversion also diverts bolus toward esophagus (liquid vs. solid)
Aryeipiglottic folds
¥ False (Ventricular folds) & True vocal folds
Pharyngeal contractions
¥ Sequential contractions of the superior, middle and inferior pharyngeal constrictors
¥ The bolus moves inferiorly via a combination of
¥ gravity
¥ base of tongue retraction
¥ pharyngeal wall contraction
¥ Upper esophageal sphincter (UES) opens/relaxes
Stage 4: Esophageal Phase
Involuntary
¥ Involuntary:
¥ 8~20 seconds in adults
¥ 3~10 seconds in infants
¥ Point where bolus enters esophagus at UES to point where bolus passes into stomach at LES
¥ Larynx descends to rest position and respiration resumes (exhalation)
¥ Velum lowers (VP port open)
¥ UES contracts/closes
Stage 4: About the Opening of the UES
¥ The UES is likely composed of multiple muscles
¥ Cricopharyngeal muscle = pharyngeal-‐esophageal m.
¥ Opening of the UES allows the bolus to enter the esophagus
¥ Opening occurs before the bolus arrives and contributes to the pressure differential within the pharynx
¥ The UES relaxes during the swallow
¥ Elevation of the larynx pulls UES open
¥ Duration of opening increases as bolus volume increases
Stage 4: More about Esophageal Phase
¥ Another entrance of bolus into the esophagus, the food is carried to the stomach via gravity and esophageal peristalsis.
¥ Passage of food through the hypopharynx is NOT considered to be due to “peristalsis.” ( pharyngeal muscle contraction)
Circular smooth muscle contract behind, relaxes in front of the bolus
Stage 4: More about Esophageal Phase
¥ LES closes another food enters the stomach
¥ If dysfunction -‐> Reflux
¥ Esophagus joins the stomach through an opening in the diaphragm called the “diaphragmatic” or “esophageal” hiatus.
¥ “Hiatus hernia”
Four Mechanism of Airway Protection
- Hyoid/laryngeal elevation away from path of bolus
- Epiglottis retroflexion
¥ Elevation of the larynx to approximate the hyoid bone results in flipping the epiglottis over to a more vertical position. - Closure of the laryngeal vestibule
¥ (bounded by the epiglottis, aryepiglottic folds, and arytenoid cartilages) - Adduction of the false/true vocal folds
Protective Reflexes
Protective Reflexes
¥ Cough reflex
¥ Gag reflex:
¥ Test the integrity of CN X
Cough reflex
¥ In response to material entering deep into the laryngeal vestibule.
¥ Innervated by CN X (both motor and sensory)
Gag reflex:
¥ Gag reflex: sensory CN IX, motor CN X
¥ Many individuals with normal swallowing have an absent gag reflex
¥ What does it have to do with swallowing?
¥ Triggered by noxious stimuli
¥ Designed to squeeze material out of the pharynx
Oral Preparatory & Transport Phase
¥ Tongue positions material on the teeth
¥ Back of tongue and so palate seal
¥ Rotary lateral movement of the mandible and tongue during mastication
¥ Aer cycle is repeated numerous times, a bolus is formed
¥ During active chewing, the velopharyngeal port remains open for breathing.
¥ Little amount of premature spillage at valleculae is common (normal)
Pharyngeal Phase
¥ Elevation and retraction of the velum and complete closure of the velopharyngeal to prevent passage into the nasopharynx
¥ Pharyngeal contraction and BOT retreats to PPW
¥ Elevation and anterior movement of the hyoid and larynx
¥ Closure of the larynx at the true vocal folds, the laryngeal entrance and the epiglottis to prevent material from entering the airway
¥ USE opens
Summary: Events in Normal Swallow
- Bolus resting on tongue dorsum, tongue tip elevates
- Lingual-‐velum seals
- Tongue (elevates) propels bolus moving backward (initiating a swallow)
- Initiate a swallow (to trigger swallowing reflex -‐> More automatic processes of swallowing begin
- Velum elevates to seal nasopharynx
- Tongue base (pharyngeal tongue) moves forcefully to meet pharyngeal wall and squeeze bolus downward
- Pharynx constricts
- Epiglottis inverts
- Larynx closes (airway closes at 3 levels)
- Hyoid bone and larynx move superiorly and anteriorly (away from the airway)
- UES region opens to allow bolus to enter esophagus
