Swallowing Flashcards
What is swallowing?
Swallowing is the action of preparing food within the oral cavity. Transmitting the prepared bolus from the oral cavity through the pharynx and oesophagus to the stomach.
What are the 3 phases of swallowing?
1 - Oral Phase (Oral preparatory phase).
2 - Pharyngeal Phase.
3 - Oesophageal Phase.
State whether the phases are voluntary or involuntary?
Oral Phase = Voluntary
Pharyngeal Phase = Involuntary (Reflex)
Oesophageal Phase = Involuntary (Reflex)
Explain the process of the oral preparatory phase.
Preparation of food by mastication and mixing with saliva.
Consistency of food is monitored by sensory receptors in the oral mucosa.
Moist food is collected into a bolus mainly by tongue working against teeth and hard palate.
Oral Cavity is occluded by raising the tongue to the palate from front to back, pushing food towards oesophagus.
Back of tongue lowered creating a shute, food is pushed into oropharynx by backward tongue thrust.
Explain the main actions in the pharyngeal phase.
Passage of food through pharynx.
Protection of lower airway to prevent inhalation of food.
Passage of bolus by sequential contraction of three pairs of pharyngeal constrictor muscles (CN X).
How does the pharyngeal protect the lower airway?
- Suspension of respiration.
- Elevation of larynx by suprahyoid muscles.
- Narrowing of laryngeal entrance.
- Strong adduction of vocal folds.
Explain Laryngeal Elevation
- Opens pharynx
- Pulls larynx under the tongue
- As tongue moves back, epiglottis flaps over laryngeal entrance.
- Epiglottis is convex anteriorly so food is directed laterally away from laryngeal entrance into pyriform recesses.
- Laryngeal entrance cant be closed off but narrowed to minimise risk of inhalation.
Explain Laryngeal Elevation
- Opens pharynx
- Pulls larynx under the tongue
- As the tongue moves back, the epiglottis flaps over laryngeal entrance.
- Epiglottis is convex anteriorly so food is directed laterally away from laryngeal entrance into pyriform recesses.
- Laryngeal entrance cant be closed off but narrowed to minimise risk of inhalation.
- Vocal folds strongly adducted by action of interarytenoids and cricoarytenoids.
What happens in the oesophageal phase?
Food is passed down the oesophagus to the stomach by action of oesophageal muscles to enter stomach.
Swallowing takes 1.5-2seconds.
What is the cough reflex and its role?
It expels mucus from the respiratory system. Innervated by CN X.
A cough causes the diaphragm and IC muscles contract. Glottis closes and VF’s adduct causing increased sub glottal pressure. Bronchi and non cartilaginous portion of trachea collapse.
What is the Gag Reflex and its role?
Occurs if swallowing reflex is elicited but material cannot be swallowed. Soft palate elevated to stop material entering nasopharynx.
What are the sensory nerves involved in swallowing?
