1) Mastication involves chewing food into small pieces to aid digestion and expose it to saliva. 2) Swallowing has three phases - oral, pharyngeal, and esophageal. In the pharyngeal phase, swallowing receptors trigger cranial nerves which close the nasal passage and larynx and push food into the esophagus. 3) The esophageal phase uses peristalsis and gravity to propel food through the esophagus and into the stomach, while swallowing is regulated by afferent and efferent cranial nerve impulses.

1. Mechanism & Regulation of
Mastication & Deglutition
Dr. Sara Sadiq
(MBBS, M.Phil)

2. Mastication
Processes involved in food preparation, including
moving unchewed food onto the grinding surface
of the teeth, chewing, it, and mixing it with
saliva in preparation for swallowing

5. Significance of Chewing Reflex
1. Breaks the food into small pieces to be easily swallowed
2. Expose food to salivary amylase enzyme, which begins
digestion of starch
3. Help digestion of all types of food especially cellulose
containing food e.g. vegetables

6. Swallowing Or Deglutition
•Swallowing is the transport of food from mouth to stomach
• It consists of 3 phases or steps;

7. 1. Oral Phase (Voluntary Stage)

8. 2) Pharyngeal Phase (Involuntary Stage)

9. 2) Pharyngeal Phase (Involuntary Stage)
Bolus in posterior mouth stimulate swallowing receptor  afferent
impulses through 5th and 9th cranial nerve  to medulla and pons 
effernt impulses causes:
• Soft palate pulls upward closes nares
• Palatopharyngeal folds pulled medially
• Epiglottis closes the larynx
• Neck muscle over hyoid bone pull larynx upward causing stretch of
esophageal sphincter
• Superior constrictor muscle of pharynx contracts and produce
peristaltic wave

10. Deglutition Apnea
• During Pharyngeal stage swallowing center inhibits
respiratory center for 1-2 seconds

11. 3) Esophageal Phase (Involuntary Stage)

12. 3) Esophageal Phase
Three factors participate:
1. Primary Peristalsis  Continuation of peristaltic wave begins in
pharynx  propel most of bolus into stomach
2. Secondary Peristalsis  Distension of esophagus  Mynteric
stimulation  Vagal reflex  relaxation of gastroesophageal
sphincter
3. Gravity

13. Regulation of swallowing act
• Afferent impulses  5th,7th,9th and 10th cranial nerves 
Stimulation of the superior laryngeal nerve  reflex swallowing
• Efferent nerves  9th, 10th and 12th nerves.