Chapter 10 Flashcards
The 4 steps or phases
Oral preparation
Oral transit
Pharyngeal
Esophageal
Dentition and mandibular mm during mastication and oral preparation
Dentition and mandibular mm provide structures and motion for the actual chewing
Mandibular mm work in a semi-rotary fashion to support dental grinding
Mastication or Oral Preparation
Mastication requires that food does not spill anteriorly (i.e., a good labial seal) or posteriorly (i.e., posterior tongue and velum) or laterally (i.e., buccal mm)
Lingual action assists in moving the food off/onto the dental grinding surfaces
Salivary glands help in creation of a cohesive bolus
Velum is depressed: breathing through nose
Following oral preparation
Following oral preparation, the bolus is gathered in the anterior aspect of the mouth and moved towards the posterior via a stripping motion of the tongue against the hard palate
Additional events include during oral transit
Persistent labial seal
Velum is depressed then elevated
Persistent buccal mm contraction
The swallow reflex
The swallow reflex is triggered when the bolus reaches about the level of the anterior faucial pillars
With triggering of the swallowing reflex, various pharyngeal events begin to occur
Pharyngeal Phase I
Velo-pharyngeal closure occurs
Hyo-laryngeal excursion along with bolus pressure assist in inversion of the epiglottis
Laryngeal closure and hyo-laryngeal elevation and anterior movement occur as well as apnea to protect the airway
Pharyngeal Phase II
As the bolus enters the pharynx, sequential pharnygeal mm contraction along with base of tongue mm contraction help to move the bolus in an inferior direction along with gravity
Hyo-laryngeal traction and crico-pharyngeal contraction help to open the upper esophageal sphincter
The bolus passes into the esophagus
The upper esophageal sphincter closes
Esophageal phase
Successive contraction of esophageal mm propel the food towards the LES
LES contraction occurs, relaxing the muscle, and allows for passage of the bolus into the stomach
Pressures in deglutition
Recall the tendency for equilibrium in pressure systems (molecules will move from higher to low pressure regions)
Positive pressure is developed at various locations in the aero-digestive tract to assist in bolus propulsion
Anterior oral cavity by tongue against palate
Posterior tongue and pharyngeal walls
Lower pressure at cricopharyngeus 2° to laryngeal elevation
Reflex
: involuntary responses to stimulation
Many reflexes extinguish over time with development/maturation
Infant anatomy
Infants have Smaller oral cavities Elevated and anteriorly placed larynges Drop after ~4 years No dentition Larger velum Elongated nasopharynx
rooting reflex
The newborn gains nutrition through rooting reflex
Infant responds to tactile stimulation of lips or cheek
Infant turns toward stimulus and opens mouth
Suckling reflex
Suckling reflex allows infant to receive food from mother’s breast in first six months
Triggered by contact to inner margin of lips causing piston-like tongue protrusion and retraction
Replaced by sucking - more complex process causing negative pressure to draw liquid in
When infants feed
Forward lingual pumping draws milk into the mouth (posterior tongue is elevated, velum “locks” into space bw epiglottis and tongue)
After 4 or 5 lingual thrusts, a swallow is triggered and the tongue base lowers
Next thrust will cause milk to enter oropharynx
Milk passes around epiglottis and via pyriform sinuses into esophagus
Respiration continues
