DEGLUTTITION (SWALLOWING)

Is a phenomenon of reflex sequence of muscle contractions that propels the ingested materials and pooled saliva from the mouth to the stomach.
PATTERNS
Infantile (visceral) swallow
Adult/mature swallow
ADULT SWALLOWING
Is composed of 4 stages
Voluntary
Preparatory phase
Oral or buccal
Involuntary: Controlled By Medulla and Lower Pons
Pharyngeal
b. Oesophageal

1. DEGLUTTITION (SWALLOWING) Dr AMITHA G, BDS, MDS ORAL AND MAXILLOFACIAL PATHOLOGY

2. DEFINITION Is a phenomenon of reflex sequence of muscle contractions that propels the ingested materials and pooled saliva from the mouth to the stomach PATTERNS Infantile (visceral) swallow Adult/mature swallow

3. INFANTILE SWALLOW Newborn and infants feed by a process called suckling in which the intake consists of fluids. Fetus is capable of sucking and swallowing amniotic fluid in utero, indicating that the motor programme for these activities is developed even before birth. The fetal swallowing takes place at the rate of 7-20 times/day .

4. STEPS IN INFANTILE SWALLOWING In newborn, jaws are apart during the swallow. The tongue is placed b/w the jaws to provide anterior seal. The mandible is stabilized mainly by the contraction of muscles of 7 th nerve (facial nerve) and the interposed tongue. The lower jaw and tongue are elevated, the tongue is grooved allowing the milk to flow posteriorly into the pharynx and oesophagus Negative pressure of 50-200 mm of Hg is created during suckling.

5. ADULT SWALLOWING Is composed of 4 stages Voluntary Preparatory phase Oral or buccal Involuntary: Controlled By Medulla and Lower Pons Pharyngeal b. Oesophageal

6. PREPARATORY PHASE The aim of this stage is to convert the food into a bolus which can be easily swallowed Starts as soon as liquids are taken into the oral cavity or after the bolus has been masticated. The liquid or bolus is positioned on the dorsum of the tongue, with the oral cavity sealed by the lip and the tongue. The food is rolled adequately on the upper surface of the tongue  saliva is mixed with the food (with the help of tongue)  to form a bolus  transferred.

7. ORAL OR BUCCAL STAGE The bolus is formed and transported under voluntary control to the pharynx. The initiation of the first stage is voluntary. Events taking place are

8. Bolus transferred to the posterior aspect of dorsum of tongue (which is depressed) anterior portion of tongue is elevated contact the palate lips are closed and prevent the escape of food out the teeth of upper jaw and lower jaw contact each other  the area of contact between the tongue and palate moves posteriorly due to the action of intrinsic muscles of the tongue suprahyoid muscles contract  raise the hyoid bone and tongue.

9. In the last part of the oral phase contraction of styloglossi and palatoglossi posterior part of tongue gets raised bolus slides into pharynx. The tongue remains in this elevated position seal the oropharyngeal isthmus  preventing the regurgitation of food.

10. SECOND STAGE (PHARYNGEAL STAGE) Aim of this stage is to make sure that the bolus enters the esophagus and not into respiratory tract. Following receipt of the bolus, the pharynx is activated to propel the food to the oesophagus . Events taking place are

11. Raising of the soft palate (to prevent the regurgitation into nasopharynx) Tensor and levator palatine muscles contract soft palate gets tensed and rises posterior wall of the nasopharynx approaches towards the soft palate nasopharynx is sealed off  preventing the regurgitation of food.

12. Pulling of the larynx (to prevent the entry of food into larynx) Stylopharyngeus , palatopharyngeus and salpingopharyngeus muscles larynx is pulled upwards to fit with epiglottis  which seals the opening and prevents entry of food into the larynx aryepiglottic and oblique arytenoids muscles contract closes the aryepiglottis folds food enters pharynx. As the respiratory passage is closed, breathing temporarily ceases

13. Propelling movement in pharynx Once food entered pharynx  contraction of pharyngeal constrictor muscles from above downwards propels the bolus of food into the oesophagus .

14. THIRD STAGE (ESOPHAGEAL STAGE) Is the passage of bolus down the oesophagus to the stomach by oesophageal contraction Oesophagus has 2 sphincters Upper or superior Lower

15. Contact of food opens the upper sphincter  allow the entry of food into oesophagus Bolus enters the esophagus the upper esophageal sphincter closes so that the food does not enter back into the pharynx a wave of peristalsis is initiated at the upper end of the oesophagus travels downwards (aboral direction)  propelling the bolus downwards  the downward movement of the food is helped considerably by the action of gravity. Lower oesophageal sphincter opens  food enters the stomach

16. NERVOUS REGULATION ORAL PHASE Is voluntary Deglutition centre to control involuntary swallowing movements is MEDULLA . Afferent impulses travel from Oropharynx through the GLOSSOPHARYNGEAL NERVE. Motor impulses travel down the motor nerves supplying the various muscles involved in swallowing.

17. APPLIED PHYSIOLOGY DYSHAGIA Is difficulty in swallowing. Causes Mechanical obstruction of pharynx or oesophagus Due to cancers and other growths Foreign bodies Pressure on the pharynx by surrounding structures like thyroid gland tumors Paralysis of tongue Cancer of tongue Nerve dysfunctions Bulbar paralysis of poliomyelitis, hydrophobia, Myasthenia gravis. Inflammations of the tongue, mouth and pharynx.

18. PARALYSIS Of the muscles of palate or the pharynx results in failure to seal of the nasopharynx from the buccal cavity and during swallowing  liquid fluids therefore, regurgitate through the nasal cavity. Such paralysis can occur due to bulbar poliomyelitis or other neurological disorders where brain stem is involved. Such diseases may develop after an attack of diphtheria

19. VOMITTING Is the co-ordinated action of the muscles of the stomach, oesophagus and abdominal wall to eject the contents of the stomach through the mouth. Respiration is inhibited during vomiting. It is the powerful pressure exerted by the contracting abdominal muscles upon the RELAXED STOMACH that results in vomiting. Vomiting is caused by a local irritation in the duodenum or stomach or by direct stimulation of the vomiting center of the medulla.

20. Thank you