Anatomy/Physiology of Swallowing

Question 1

what are the 3 phases swallowing consists of

Answer 1

oral phase(voluntary), pharyngeal phase(involuntary), oesophageal phase(involuntary)

Question 2

describe the mastication part of the oral phase of swallowing

Answer 2

masticatory muscles(CN V3) breakdown food and allow it to mix with saliva

Question 3

describe the bolus manipulation part of the oral phase of swallowing

Answer 3

intrinsic and extrinsic tongue muscles(CN XII) manipulate bolus and align it between dentition and push it against hard palate

Question 4

describe the action of the soft palate in the oral phase of swallowing

Answer 4

depresses to create and oropharyngeal seal and tongue ‘ripples’ bolus exteriorly

Question 5

what role does the facial nerve(CN VII) have in the oral phase of swallowing

Answer 5

creates labial seal(orbicularis oris) and tightens the cheek(buccinator)

Question 6

what innervates the hard palate

Answer 6

branches of the pterygopalatine ganglion, therefore secretomotor function by CN VII and general sensation by CN V2

Question 7

describe the course of CN XII

Answer 7

extends from the medulla, passes through hypoglossal canal, descends close to carotid sheath, courses lateral to hypoglossus into floor of mouth

Question 8

what muscles of the tongue does CN XII(facial nerve) innervate

Answer 8

all muscles of the tongue that end on glossus

except palatoglossus

Question 9

what are the extrinsic muscles of the tongue

Answer 9

genioglossus, hyoglossus, styloglossus and palatoglossus

Question 10

what is the pharyngeal phase of swallowing initiated by, and why is it a critical phase

Answer 10

delivery of bolus to oropharynx, critical as switches from air channel to food channel

Question 11

what actions is the pharyngeal phase of swallowing facilitated by

Answer 11

elevation of soft palate, posterior pressure from tongue, hyolaryngeal elevation and pharyngeal constrictor contraction

Question 12

describe the action of hyolaryngeal elevation

Answer 12

hyoid dragged superiorly and anteriorly by suprahyoid and longitudinal pharyngeal muscles, coupled with posterior tongue pressure
forces epiglottis inferior to tongue and covers laryngeal aditus

Question 13

what is the movement of food bolus through the laryngopharynx and into the oesophagus aided by

Answer 13

tongue pressure, sequential contraction of pharyngeal constrictors superior to inferior, relaxation of upper oesophageal sphincter(cricopharyngeus)

Question 14

what does the pharyngeal plexus innervate and what is it formed by

Answer 14

innervates = muscles of soft palate and pharynx, except tensor veli palatini
formed by CN IX and CN X