Deglutition (Swallowing)

Deglutition (Swallowing) Figure 22.13a-c

Deglutition (Swallowing) • Involves the coordinated activity of the tongue, soft palate, pharynx, esophagus and 22 separate muscle groups • Buccal phase – bolus is forced into the oropharynx • Pharyngeal-esophageal phase – controlled by the medulla and lower pons • All routes except the one into the digestive tract are sealed off • Peristalsis moves food through the pharynx to the esophagus

infantile (or immature) swallow has the following characteristics: 1. The jaws are apart, with the tongue between the gum pads; 2. The mandible is stabilized mainly by contraction of the muscles innervated by the VII (seventh) cranial nerve and the interposed tongue; 3. The swallow is guided and to a great extent controlled by sensory interchange between the lips and the tongue

mature swallow Usually, by 18 months of age, the following mature swallow characteristics are to be observed: 1. The teeth are together; 2. The mandible is stabilized by contraction of the mandibular elevators, these being primarily innervated by the trigeminal nerve; 3.The tongue tip is held against the palate above and behind the incisors; 4.There are minimal contractions of the lips during the mature swallow.

Theories of deglutition • THEORY OF CONSTANT PROPORTION • THEORY OF ORAL EXPULSION • THEORY OF NEGATIVE PRESSURE • THEORY OF INTEGRAL FUNCTION

THEORY OF CONSTANT PROPORTION 1. Oral phase; the bolus is formed and transported under voluntary control to the pharynx; 2. Pharyngeal phase; following receipt of the bolus, the pharynx is activated to propel the food to the oesophagus; 3. Oesophageal phase; passage of bolus down the oesophagus to the stomach by oesophageal contraction

THEORY OF INTEGRAL FUNCTION • based on cinefluorographic, myometric and electromyographic studies, and considers that the act of deglutition is a total dynamic process. This is the currently accepted theory

THEORY OF INTEGRAL FUNCTION Phases of the mature deglutition cycle 1. Preparatory phase 2. Oral phase 3.Pharyngeal phase 4.Oesophageal phase

1. Preparatory phase • starts as soon as liquids are taken into the oral cavity or after the bolus has been masticated. • The liquid or bolus is position on the dorsum of the tongue, with the oral cavity sealed by the lip and the tongue. • The positioning of a liquid on the dorsum of the tongue before transporting it to the final swallow-preparatory position may be facilitated through suction created by moving the tongue posteriorly after a peripheral seal has been established within the cavity.

1. Preparatory phase • A final characteristic is the stabilization of the oral cavity • 'Considerable pressure' is exerted between the teeth in the molar region as the lip is elevated to position the bolus in adult subjects, although it is apparent that in the predentition or mixed dentition phases, other mechanisms would need to be used for this purpose.

2. Oral phase • introduced by the withdrawal of the soft palate from its rest position against the root of the tongue, where it is held by the tensor palati muscles. • In this phase the soft palate moves upward and the tongue drops downward and backward. • At the same time, the larynx and hyoid move upward. • The elevation of the hyoid may actually be initiated as the bolus is positioned in the swallow-preparatory phase.

2. Oral phase • These combined movements make a smooth path for the bolus as it is pushed from the oral cavity by the peristaltic-Iike action of the tongue. • Solid food is actually pushed by the tongue, whereas fluids flow ahead of the lingual contractions. • During this phase, the oral cavity maintains an anterior and lateral seal, and is stabilized by the muscles of mastication.

2. Oral phase • When a large bolus is to be swallowed, most or all of it is moved into the preparatory position and is then neatly sectioned by the tongue in consecutive swallows until the oral cavity is empty.

3.Pharyngeal phase • This phase begins as the bolus passes from the tongue through the fauces. • The pharyngeal tube is raised and the nasopharynx sealed by closure of the soft palate against the posterior pharyngeal wall. • Active participation of the pharynx is elicited by soft palate and bolus contact with the pharyngeal wall, an action which consists of an elevation of the entire

3.Pharyngeal phase • pharyngeal tube and a sphincteric reduction in the lumen between the upper pharyngeal wall and soft palate. • The hyoid and the base of the tongue move forward as both the tongue and the pharynx continue their peristaltic-like action on the food bolus. • Passage of such a bolus through the pharynx during the mature swallowing is enhanced by an anterior movement of the hyoid and root of the tongue.

3.Pharyngeal phase • Finally, there is an abrupt elevation of the larynx as the bolus reaches the laryngo-pharynx and, this is then followed by elevation of the floor of the laryngophary and opening of the oesophageal sphincter.

4.Oesophageal phase • This phase commences as soon as food passes the cricopharyngeal sphincter. While peristaltic movement carries the food through the oesophagus, the hyoid bone, soft palate and tongue return to their 'original positions'.

Deglutition (Swallowing) Figure 22.13d, e

Esophagus • Peristalsis: • Produced by a series of localized reflexes in response to distention of wall by bolus. • Wave-like muscular contractions: • Circular smooth muscle contract behind, relaxes in front of the bolus. • Followed by longitudinal contraction (shortening) of smooth muscle. • Rate of 2-4 cm/sec. • After food passes into stomach, LES constricts. Insert 18.4a

MOVEMENTS OF THE GUT

Stomach • Most distensible part of GI tract. • Empties into the duodenum. • Functions of the stomach: • Stores food. • Initiates digestion of proteins. • Kills bacteria. • Moves food (chyme) into intestine.

Conclusion for swallowing

Oral Preparatory Phase • tongue positions material on the teeth • rotary lateral movement of the mandible and tongue during mastication • tongue moves the material back onto the teeth as the mandible opens • after cycle is repeated numerous times, a bolus is formed • during active chewing, the soft palate is not pulled down and forward and premature spillage is common and entirely normal

Pharyngeal Phase • elevation and retraction of the velum and complete closure of the velopharyngeal to prevent passage into the nasopharynx • elevation and anterior movement of the hyoid and larynx • closure of the larynx at the true vocal folds, the laryngeal entrance and the epiglottis to prevent material from entering the airway

Second swallow • A second swallow was needed to clear all the material • 1/3 Teaspoon Ground Meat and 1/4 Cookie In this segment, please note: • The rotary lateral movement of the mandible and tongue • The formation of the bolus • During chewing, the soft palate is not pulled down and forward and material falls into the pharynx partially before the pharyngeal phase is triggered • Bolus size decrease with the viscosity of food; J.P. swallowed twice on the ground meat material

Control of deglutition

Speech • 1 Speech Mechanism • Physiological phonetics • All sounds which come from the mouth and nose arethe result of interruptions and/or modifications of a stream of air moving from the lungs through: • trachea - larynx • pharynx - oral cavity • nasal cavity

4 speech process – respiration – phonation – resonation – articulation*

Articulation • structures of pharynx, nasal and oral cavity • way of modifying airstream • articulation = joining together of speech organs for production of phonemes

lips – supported by maxilla (upper jaw) and lower jaw (mandible) – Body function - receive and contain food – Speech function - varied movement: rounded, tensed: obstruct air flow

teeth – body function - cut and grind food – speech function - anatomical obstacle for lips or tongue • alveolar ridge (gum ridge of maxilla – body function - none; houses teeth – speech function - point of contact/constriction

hard palate- bony structure posterior to alveolar ridge – body function - contain food in oral cavity – speech function - point of contact; defines shape of oral cavity

soft palate/velum - muscular structure posterior to hp – body function - separate oral cavity and nasal cavity – speech function - direction of air flow -open/close vp port: point of contact

tongue -major articulator/ muscle and mobile – body function - direct food to back of oral cavity – speech function - direction of air flow: contacts

other structures : approximates other structures; • changes size of oral cavity mandible – body function - chewing – speech function - change size of oral cavity

Oral cavity – from mouth opening to posterior wall of pharynx (posterior pharyngeal wall) – body function: breathing, eating – speech: channels airstream: contributes oral resonance • Nasal cavity - extends from nostrils (nares) to posterior

Pharynx – posterior portion of nasal cavity down through back of oral cavity to larynx – body function: breathing – speech: contributes nasal resonance • Vocal cords/folds – in lateral walls of larynx – body function: respiratory protection – phonation

Thank you for your attention

Deglutition (Swallowing)