Swallowing Flashcards
What are the 4 stages of swallowing?
- Cephalic
- Oral stage (voluntary)
- Pharyngeal stage (involuntary)
- Oesophageal stage
What is the cephalic stage of swallowing?
Thinking about eating
What are the 3 components of the oral stage of swallowing?
- Mastication
- Salivation
- Movement of the bolus
Oral Stage: Mastication
- What is the purpose of this stage?
- What is the action of the incisors?
- What is the action of the molars?
- Increase surface area for enzymatic action
- Cutting action
- Grinding action
Oral Stage: Movement of the bolus
- Which structures help to direct the bolus posteriorly?
Rugae of the hard palate
Describe the 4 stages of the chew reflex
- Food bolus causes reflex inhibition of the muscles of mastication and the jaw drops
- Initiates the stretch reflex of the jaw muscles, leading to rebound contraction
- Jaw rises and the teeth close causing compression of the bolus against the mouth lining and the jaw muscles are inhibited
- Jaw drops again and rebounds
Describe the pharyngeal stage of swallowing
- Epithelial swallowing areas are stimulated
- Soft palate elevates upwards to close the posterior nares to prevent reflux of food into the nasal cavities
- Palatoglossal folds pulled medially to allow only sufficiently chewed food through
- Vocal cords of the larynx close and the larynx is elevated which closes the epiglottis
- Upper Oesophageal Sphincter relaxes and opens
- Coordinated contraction of the pharynx (superior, middle and inferior) to propel food by peristalsis
What 3 structures constitute the upper oesophageal sphincter?
- Cricopharyngeus
- Inferior pharyngeal constrictor
- Proximal cervical oesophagus
Which cranial nerve innervates the upper oesophageal sphinctor?
CN X (Vagus)
What causes the upper oesophageal sphincter to open?
Cessation of vagal innervation of the cricopharyngeus muscle
Which area of the CNS controls the swallowing response?
Brainstem Central Programme Generator (CPG)
Which nuclei are involved with swallowing?
Dorsal vagal motor nucleus
Nucleus ambiguus
Which cranial nerves are involved with swallowing?
CN 5, 7, 9, 10 and 12
How many muscles are involved with swallowing??
26 muscles
Swallowing: Oesophageal Stage
- What is primary peristalsis?
- What is secondary peristalsis?
Primary peristalsis: Continuation of the peristaltic wave from pharynx in the pharyngeal stage
Secondary peristalsis: Not all food passed to stomach so distention of the oesophagus results in myenteric plexus and vagal afferents stimulating the response
