what are the 3 phases swallowing consists of
oral phase(voluntary), pharyngeal phase(involuntary), oesophageal phase(involuntary)
describe the mastication part of the oral phase of swallowing
masticatory muscles(CN V3) breakdown food and allow it to mix with saliva
describe the bolus manipulation part of the oral phase of swallowing
intrinsic and extrinsic tongue muscles(CN XII) manipulate bolus and align it between dentition and push it against hard palate
describe the action of the soft palate in the oral phase of swallowing
depresses to create and oropharyngeal seal and tongue ‘ripples’ bolus exteriorly
what role does the facial nerve(CN VII) have in the oral phase of swallowing
creates labial seal(orbicularis oris) and tightens the cheek(buccinator)
what innervates the hard palate
branches of the pterygopalatine ganglion, therefore secretomotor function by CN VII and general sensation by CN V2
describe the course of CN XII
extends from the medulla, passes through hypoglossal canal, descends close to carotid sheath, courses lateral to hypoglossus into floor of mouth
what muscles of the tongue does CN XII(facial nerve) innervate
all muscles of the tongue that end on glossus
except palatoglossus
what are the extrinsic muscles of the tongue
genioglossus, hyoglossus, styloglossus and palatoglossus
what is the pharyngeal phase of swallowing initiated by, and why is it a critical phase
delivery of bolus to oropharynx, critical as switches from air channel to food channel
what actions is the pharyngeal phase of swallowing facilitated by
elevation of soft palate, posterior pressure from tongue, hyolaryngeal elevation and pharyngeal constrictor contraction
describe the action of hyolaryngeal elevation
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
what is the movement of food bolus through the laryngopharynx and into the oesophagus aided by
tongue pressure, sequential contraction of pharyngeal constrictors superior to inferior, relaxation of upper oesophageal sphincter(cricopharyngeus)
what does the pharyngeal plexus innervate and what is it formed by
innervates = muscles of soft palate and pharynx, except tensor veli palatini
formed by CN IX and CN X
