The document summarizes the three stages of swallowing (deglutition): 1) Buccal stage where the tongue retracts forcing the bolus into the oropharynx. 2) Pharyngeal stage is involuntary where the soft palate and larynx elevate to prevent food entering the nasal cavity and lungs. The bolus moves into the upper esophagus. 3) Esophageal stage where peristalsis propels the bolus through the esophagus and into the stomach over 8-20 seconds while the lower esophageal and stomach sphincters relax.

1. Mechanism of swallowing
(deglutition)
PREPARED BY: MUHAMMAD ARIFF B. MAHDZUB
BACHELOR MEDICINE AND SURGERY (MBBS)
UNIVERSITY COLLEGE SHAHPUTRA, KUANTAN

2. Mechanism of swallowing
(deglutition)
The sequence events:
a. Buccal stage (voluntary)
b. Pharyngeal stage (involuntary)
c. Oesophageal stage (peristalsis)

3. Buccal stage (voluntary)
• The tongue retracts to force the bolus into the
oropharynx by the contraction of mylohyoid
muscle

4. a) protective phase
• They soft palate rises to close
off nasopharynx and prevent
bolus from rising into the
nasal cavity
• The larynx elevate and the
glottis closes(by epiglottis)
Pharyngeal Stage (involuntary)

5. • Oropharyngeal isthmus closed
(Base of tongue touching the soft
palate)
• Pharyngeal constrictor contract

6. b) pharyngeal peristalsis
• as pharyngeal constrictor contract, the UES
relaxes to allow the bolus to move from the
oropharynx into the upper oesophagus

7. Oesophageal Stage (8-20 seconds)
• Primary peristalsis begins and both the LES
and stomach relax
• The bolus moves into stomach and LES closes.
• water bolus moves by gravity while semisolid
by peristalsis
• Peristalsis rapid in upper third while slow in
lower third, it starts as primary ( continuation
of pharyngeal) or secondary by oesophagus if
primary failed

8. PBL cases
• Ms Senna, got bulging at her neck

9. Patient information sheet 2

11. • Bulging move up as its
follow the larynx
elevation (Pharyngeal
Stage)
• Enlrg. thyroid wraps
around esophagus
• Compressed the
pharynx and
oesophagus lead to
Dysphagia
-Swelling moves up during swallowing-

12. -There s bruit heard over neck swallowing-
• Bruit : vascular murmur
• Causes: compression of enlarge thyroid gland
to blood supply