Normal Swallowing

Oral phase

Pharyngeal phase

Oesophageal phase

Oral prep phase

Manipulate food or liquid to form cohesive bolus for swallowing

Mastication, combine food with saliva, tasting food, forming bolus of appropriate size, consistency to move into next stage

Duration depends on bolus consistency, under volitional control

Airway is open, breathing mainly via nasal airways

Structures: Lips, anterior 2/3 of tongue for bolus prep, extrinsic and intrinsic muscles to shape bolus

Liquids: BOT raised, velum lowered, draped close to BOT

Solids: Tongue moves bolus laterally to molar ridges, crushing rotatory mvt of jaw masticates bolus, crushing continues reflexively, can also be cortical input.

Active chewing: Velum is in normal resting position up away from BOT, prem spillage NORMAL

No active chewing: Velum draped down and forward to touch BOT, partially seal off oral cavity from pharynx

Cranial nerves

CN5: mechanical, temp

CN7: anterior 2/3 of tongue taste

CN9: posterior 1/3 of tongue

Neuro

Brainstem then integrated in nucleus tractus solitarius of medulla & cortical control: Info taste, temp, bolus size, how much to masticate

General info

Voluntary stage (1s-1.5s)

Tongue propels bolus into oropharynx then into hypopharynx. Ends with trigger of swallow. Reflex and voluntary

Bolus held in mid-central groove w lateral edges of tongue against hard palate, lateral side of teeth

Lips, buccal muscles contract, velum raised and retracted to close off nasopharynx. Build up pressure in pharynx. Inward mvt of posterior, lateral pharyngeal walls

Posterior of tongue depresses, anterior tongue presses against hard palate propelling bolus backward-stripping action

Structures: Intrinsic muscles of tongue, change shape of tongue to form groove for bolus. Extrinsic muscles of tongue

Cranial nerves

CN5: digastric, mylohyoid

CN12: geniohyoid

Elevate hyoid up and forward

Hyoid mvt--> Cricopharyngeal (CP) sphincter [UES] opens to allow bolus to pass into oesophagus. Once bolus passed, larynx returns to original position, CP returns to original position

Progressive contraction pharyngeal constrictor muscles (Superior pharyngeal constrictor, medial, inferior): Pharyngeal stripping wave to help w bolus transport

On VFSS: Swallow triggered when bolus head reaches point where BOT crosses mandible

FEES: triggered when bolus begins to pass around epiglottis, reaches lateral channels. Liquid bolus divides at valleculae--> travels down pharynx in pyriform sinuses, then meets again at oesophagus. Solid stays as a whole, goes down 1 side

Swallowing initiation depends on sensory information: mechanical, chemical, water respondent receptors

Sensory receptors: oropharynx, tongue identify posterior propulsion of bolus, send sensory info via sensory branch of CN10 vagus to nucleus tractus solitarius--> decoded--> sent to nucleus ambiguous--> initiate pharyngeal swallow motor pattern

BOT retraction closer to PPW

Velum closes off nasal cavity- CN9 palatopharyngeal muscle, CN10,11 levator veli palatini

Hyoid moves up and forward, larynx elevates, TVF closes, closes laryngeal entrance (FVF adduct, arytenoid medialise and tilt anteriorly, epiglottic base thickens). Epiglottis deflects over laryngeal entrance, closes laryngeal vestibule

Cranial nerves

CN5: mylohyoid, anterior belly of digastric

CN12: Hypoglosus, geniohyoid

Stage starts w bolus moving through CP sphincter, stops when bolus reaches LES at opening of stomach

Bolus transported by peristaltic waves, push bolus through-> into LES--> into stomach

What facilitates bolus trf?

Tongue driving pressures- retraction

Negative pressure differential from opening of CP sphincter

Pharyngeal constrictors contracting- clearing force