The document discusses the coordination of mastication (chewing), swallowing, and breathing in the pharynx. The pharynx serves multiple functions including breathing, speaking, chewing, and swallowing. During chewing, food accumulates in the pharynx before swallowing. Swallowing requires the pharynx to change from an airway to a food passage and coordination between swallowing and breathing. Future research is needed to better understand control of structures like the soft palate and tongue during these functions as well as preventing aspiration during chewing and swallowing.

1. COORDINATION OF
MASTICATION,
SWALLOWING AND
BREATHING
Federico Villani
M24

2. INTRODUCTION
• Basically the pathways for air and food cross in the pharynx
• During swallowing the pharynx changes from an airway to a food
channel.
• During mastication, the food bolus accumulates in the pharynx prior
to swallow initiation
• Pharynx main functions:
1 Breathing
2 Speaking
3 Mastication
4 Swallowing

3. INTRODUCTION
• Food is collected in pharynx during eating and once chewed is
gradually transported through the fauces.
• It’s picked up in oropharynx, where the bolus is formed prior to
swallowing.
• Actually, the process depends on physical characteristic of food.
• During swallowing, the pharynx is used only for the food passage
and is completely separated from the airway in healthy individuals

4. PHARYNX ANATOMY
• The pharynx is the part of the throat situated inferior to the nasal
cavity, posterior to the mouth and superior to the esophagus and
larynx.
• Is divided in three parts:
① Nasopharynx
② Oropharynx
③ Laryngopharynx
• Breathing:
 Nasal breathing: soft palate is lowered and apposed to the
tongue, dilating the velopharyngeal isthmus.
 Oral breathing: soft palate elevates to open the fauces, separating
nasal cavity from pharyngeal airway.
• Mastication and swallowing: the pharynx becomes the space for
bolus aggregation prior to the pharyngeal swallow. During
swallowing the pharynx is used only for food passage, it’s
separated from the airway.

5. SEQUENCE FROM MASTICATION TO
SWALLOWING
• The normal swallow in humans is described with a four-stage
sequential model, which are:
① Oral preparatory: is carried out when we prepare the food bolus
biting and chewing, so that it can be trasformed into a
homogeneous bolus  facilitating swallowing
② Oral propulsive: After preparation, the food will be placed on the
tongue, which will engage the hard palate, initiating a wave
motion from front to back, to bring the bolus to the back of the
mouth. When it touches the anterior pillars, it triggers the
swallowing reflex itself.

6. SEQUENCE FROM MASTICATION TO
SWALLOWING
③ Pharyngeal stage: This phase is controlled neurologically by the
reticular formation associated with the respiratory center, which
determines a central coordination between swallowing and
breathing. At this stage the breathing stops for a split second
before the soft palate is closed, preventing the passage of the
bolus to the nasopharynx; glottis closes epiglottis and vocal
cords
④ Esophageal stage: it begins when the bolus passes through the
upper esophageal sphincter. The lower esophageal sphincter
muscle acts as a valve that opens to allow the passage of the
bolus into the stomach.
 The relationships among food transport, bolus aggregation, and
swallow initiation are modified by the physical characteristics of the
food

7. SEQUENCE FROM MASTICATION TO
SWALLOWING

8. COORDINATION BETWEEN
BREATHING AND SWALLOWING
• Swallowing has two essential physiologic aspects:
① passage of food from the oral cavity to the stomach
② airway protection to prevent contamination of the trachea
• There are three gate keepers to prevent and avoid
tracheopulmonary aspiration: the epiglottis, arytenoids, and vocal
folds.
• Swallowing and respiration (expiration) have tight temporal
coordination in adult humans
• The swallow respiratory temporal coordination can change and vary
with the conditions of swallowing, including method of ingestion,
body position, and food consistency.
• Swallow-respiratory coordination varies across the human lifespan
(< aged)
• The pause in breathing during swallowing is due to inhibition of
respiration at neural control centers in the brainstem

9. COORDINATION BETWEEN
BREATHING AND SWALLOWING

10. COORDINATION BETWEEN
BREATHING AND MASTICATION
• Studies reveal that the fauces are open during food processing and
triturated food is moved forward to the oropharynx, before
swallowing.
• Eating solid food alters the respiratory rhythm.
• Respiratory frequency (FR) increases during mastication, but
decreases with swallowing.
• The presence of the food in the pharynx can present a risk for preswallow aspiration, if respiration continues and the airway remains
open.
• Several mechanisms have been proposed: hypothesis that there is
an optimal cohesiveness of the food bolus for swallowing that
depends on the size of particles and the quantity of saliva

11. COORDINATION BETWEEN
BREATHING AND MASTICATION

12. DIRECTION FOR FUTURE RESEARCH
• Large gaps remain in our understanding of the neural control of the
soft palate and tongue related to breathing and mastication.
• Also in the mechanisms for preventing aspiration during
mastication and bolus aggregation.
• Investigations are needed to determine the significance of food
remaining in the pharynx for an extended period before swallowing
in indivduals with dysphagia (sympton of difficulty in swallowing).

13. CONCLUSION AND DISCUSSION
• Pharynx has an important role in the three phenomena:
mastication, breathing and swallowing, which are related each
another.
• Many studies still work on the mechanismas of inspiration and
expiration.
• The presence of the food in the pharynx before swallowing is not
necessarily abnormal, but it can increase risk of aspiration in
dysphagic individuals with poor airway protection.
• The main pharynx diseases are
I. Ambiental factors: alcohol.
II. Pharyngitis: inflammation of the throat; can be acute ( short
course) or chronic.

14. REFERENCES
• http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2749282/
• http://biology.about.com/library/organs/blpathodigest4.htm
• http://www.breathingcoordination.com/
• http://medicaldictionary.thefreedictionary.com/physiology+of+mastication
• http://www.ncbi.nlm.nih.gov/pubmed/1308667
• http://www.ncbi.nlm.nih.gov/pubmed/16172351
• http://brain.oxfordjournals.org/content/123/9/1863.full