Pharyngeal phase

Question 1

What are the three divisions of the pharynx?

Answer 1

nasopharynx
oropharynx
laryngopharynx (becomes continuous with the oesophagus)

Question 2

What triggers the swallowing reflex?

Answer 2

Tactile stimulation of sensory receptors in posterior muscosal lining of oropharynx

Question 3

Which cranial nerves are involved in the swallowing reflex

Answer 3

Afferent (sensory) limb: via trigeminal (V) and glossopharyngeal (IX) nerves to swallowing centres in medulla

Efferent (motor) limb: via trigeminal (V), glossopharyngeal (IX), vagus (X) and accessory (XI) nerves to muscles of soft palate, pharynx and larynx

Question 4

Which muscles control movement of the soft palate?

Answer 4

Tensor veli palatini (tightens/stretches)
Levator veli palatini (lifts)
Palatoglossus
Palatopharyngeus
(both elevate posterior tongue and pharynx during swallowing)
Musculus uvulae

Question 5

What happens to the velum, tongue and pharynx during swallowing?

Answer 5

Elevation and increased tention of soft palate means the palate touches the posterior wall of the pharynx, sealing off the nasal cavity
Posterior tongue elevated by palatoglossus to prevent bolus re-entering oral cavity
Elevation of pharynx by palatopharyngeus helps direct bolus backwards and down towards the oesophagus

Question 6

Outer circular layer of muscles in the pharynx _____ the pharynx

Answer 6

Outer circular layer of muscles in the pharynx CONSTRICTS the pharynx

Question 7

What do the inner longitudinal muscles of the pharynx do, and what are they called?

Answer 7

Elevates, widens and shortens the pharynx

Stylopharyngeus, salpingopharyngeus (also opens Eustachian tube, palatopharyngeus

Question 8

Which cranial nerve(s) are the inner longitudinal muscles of the pharynx innervated by?

Answer 8

Vagus nerve (X), except stylopharyngeus which is innervated by the glossopharyngeal nerve (IX)

Question 9

How is aspiration prevented during swallowing in the pharyngeal phase?

Answer 9

• elevation of the larynx
• closure of the laryngeal inlet by the epiglottis
• diversion of food/fluids into the pyraform recesses of the pharynx
• narrowing of laryngeal inlet by contraction of aryepiglottic muscles
• adduction of vocal folds
• momentary cessation of breathing

Question 10

Which muscles contract to help the epiglottis seal over the laryngeal inlet?

Answer 10

aryepiglottic muscles and oblique arytenoid muscles

controlled by vagus nerve

Question 11

Which muscles adduct the vocal folds?

Answer 11

transverse arytenoid muscle (adducts the arytenoids) and lateral cricoarytenoid muscles (rotate the arytenoids)

Question 12

Which cranial nerve innervates the UOS?

Answer 12

Vagus nerve (X)

Question 13

As the bolus reaches the lower end of the pharynx, the UOS _____. ________ of the ________________ muscle pushes food into the oesophagus.

Answer 13

As the bolus reaches the lower end of the pharynx, the UOS RELAXES. CONTRACTION of the INFERIOR PHARYNGEAL CONSTRICTOR muscle pushes food into the oesophagus.

Question 14

What happens in the pharyngeal phase?

Answer 14

Involuntary sequence of reflex muscle movements initiated by food touching trigger areas in the oropharynx

• soft palate is elevated to seal off the nasopharynx
• pharynx elevates to receive bolus
• contractions of pharyngeal constrictor muscles move bolus down through pharynx
• to prevent aspiration, the epiglottis is pushed back over laryngeal inlet
• as the bolus reaches the lower end of the pharynx, the UOS relaxes and food is pushed into the oesophagus