Physiology of pharynxDr Manpreet Singh Nanda

Associate Professor ENTMMMC& H Solan

Functions of PharynxDeglutitionRespirationVocal resonanceSecretion of mucus by mucous memebrane to

lubricate the pharynxProvides drainage to nose, oral cavity, middle

ear

Functions of NasopharynxAirway for passage of air into larynx, trachea

and lungsHearing – middle ear ventilation, maintains

air pressureResonance for voice productionDrainage for nasal and nasopharyngeal

secrtetionsPrevents aspiration (Nasopharyngeal isthmus

closes during, swallowing, vomiting, speech..

Functions of OropharynxCommon conduit for air and foodDeglutitionVocal resonanceTaste sensation (tongue base, soft palate,

anterior pillar, posterior pharyngeal wall)Local defence and immunity (Waldeyer’s

ring)

Functions of tonsils and adenoidsImmunity against bacteria, virus.... By T

Lymphocytes in parafollicular regionBarrier to infection (protective sentinels)Ig A antibody production by B Lymphocytes

in folliclesFirst 5 years life later atrophy

Functions of LaryngopharynxCommon conduit for air and foodVoice resonanceDeglutition

DeglutitionProcess of propulsion of bolus of food from oral cavity

into stomach through oropharynx controlled by neuromuscular activity

It also disposes dust and bacteria laden mucusCauses pharyngeal opening of E.T to establish equal

pressure on both sides of T.MPhases – 1. Oral – voluntary – 1 second2. Pharyngeal – both – 1 second3. Oesophageal – involuntary – 8 to 20 second..Swallowing center in Medulla near nucleus of Vagus N

Oral PhaseFood chewed Lubricated with salivaConverted into bolusHeld between tongue and palateTongue elevated against palate (myelohyoid)Food propelled into oropharynxVOLUNTARY 1 SECOND

Pharyngeal PhaseReflex actions1. Closure of Nasopharyngeal isthmus (Soft palate raised

against passavants ridge)2. Closure of Oropharyngeal isthmus (Palatoglossus muscle)3. Closure of Laryngeal inlet (contraction of aryepiglottic folds)Contraction of pharyngeal constrictors -> bolus pushed to

cricopharyngeal sphincter Relaxation of cricopharyngeus muscle (Fall in pressure) -> food

passes into oesophagusMIXED PHASE 1 SECONDNOTE – During swallowing rise in pressure of 40 mm Hg

pressure at pharyngo oesophageal junction which falls leading to relaxation of sphincter and it opens.

Oesophageal PhaseClosure of cricopharyngeal sphincterPrimary peristalsis of oesophagus (contraction of

circular muscles)Food moves downRelaxation of gastro oesophageal sphincter and

opens (X CN)Food enter stomachSphincter closesNote –Secondary peristalsis is due to oesophageal

distension (aeurbachs plexus)INVOLUNTARY 8 – 20 SECONDS

NEURAL CONTROLCN V and XII – Chewing and tongue

movementCN VII – Taste (chorda tympani), Sensory to

oral cavity (Nervus Intermedius), Motor to Orbicuilaris oris

CN IX – Taste, PharynxCN X – Taste, Larynx, Laryngopharynx

Sounds during swallowingHeard by auscultation over neck1st Sound – AT COMMENCEMENTDue to fluids acting on post pharyngeal

wall......2nd Sound – bubbling or trickling noiseAfter 4 – 10 seconds and continue 2-3

seconds

Thirst sensationPHARYNGEAL COMPONENTDehydration -> Decreased salivary secretions

-> Dry pharyngeal mucosa -> stimulation of sensory receptors (IX X CN)

CENTRAL COMPONENT (EXTRAPHARYNGEAL OR THIRST DRIVE)

High intake of salt and low water intakeIV hypertonic salineIntercellular dehydration -> Thirst......

(Hypothalamus)

DysphagiaDifficulty in swallowing due to obstruction or

interference to food passage Odynophagia – pain during swallowing Causes of odynophagia – infectious oesophagitis

due to bacteria, virus and fungi, corrosive injury, ulcers and inflammation

Symptoms – Throat discomfort, FB sensation, coughing, choking, regurgitation, heart burn, aspiration........

Causes – oral, pharyngeal, laryngeal, oesophageal, neck, CNS, CN, psychosis

Oral causesDisorder in mastication – trismus, tumour,

TM jointDisorder in lubrication – salivary glandDisorder in tongue mobility – paralysis, ulcer,

tumourTrauma, buccal ulcers, infection

Pharyngeal causesNeurological – brainstem lesions, multiple

sclerosis, myasthenia gravisMuscular – myopathy, hypothyroidismUES dysfunctionStructural – malignancy, surgeryInflammatorySpasmodic – tetanus, rabiesParalytic – palatal palsy

Oesophageal causesMechanical obstruction- malignancy , peptic

stricturesLumen obstruction – FB, strictures, tumoursWall lesions – oesophagitisMotility disorders – achalasia, diffuse

oesophageal spasm, scleroderma

External causesCervical – thyroid, cervical spondylosis,

tumours, lymphadenopathyThoracic – aneurysm of aorta, mediastinal

tumours, dysphagia lusoriaAbdominal – Hepatic enlargementDysphagia lusoria - .. Dysphagia due to

pressure on thoracic oesophagus due to vascular anomalies in chest like right aortic arch, double aorta, abnormal rt subclavian a..

Dignosis is by CT scan or angiography

EvaluationHistoryAge – child congenital causes, 20 to 40 yrs achalasia, plummer

vinson > 40 yrsSex – plummer vinson – femalesOnset – sudden in FB or food impaction, gradually progressive

in malignancy, peptic strictures, intermittent in spasmsDuration – less in inflammation, more in benignMore for liquids – achalasiaSolids progressing to liquids – malignancy, stricturesIntolerance to acid food and fruit juices – ulcerHoarseness – laryngealRegurgitation and heart burn – hiatus herniaNasal regurgitation – palatal paralysis

Aspiration into lungs – laryngeal paralysisPast history – diabetes, diptheria, poliomyelitis, FB

ingestion, globusNote – Any elderly > 2 weeks dysphagia – rule out

malignancyPlummer Vinson syndrome – females > 40 yrs,

anaemia, glossitis, koilonychia, splenomegaly, dysphagia more for solids

Achalasia – Males (mc), cardiospasm, regurgitation, more for liquids due to failure of relaxation of LES for passage of food

TO RULE OUT PSYCHIATRIC ILLNESS

Physical examinationOral cavityOropharynxHypopharynxLarynxNeckChestCranial nervesCNS

InvestigationsPan endoscopy – oesophagoscopy, laryngoscopy,

bronchoscopy, nasopharyngoscopyBarium swallow – along with fluoroscopy for malignancy,

achalasia, strictures, hiatus herniaX ray Neck – radio opaque FBChest Xray- CVS, pulmonary, mediastinal diseasesCT scan/ MRI – Neck and mediastinum, skull base Blood – haemogram (anaemia)Blood sugar – diabetesManometry and pH monitoring- GERD, acid induced

oesophageal spasmsThyoid scan , angiography

TreatmentHydration – IV fluids, ryles tube feed, feeding

gastrostomy, jejunostomyTreat the causeMedical treatment for anaemia,

inflammation, trauma, aspiration pneumoniaSurgical treatment- fracture reduction,

resection, dilatation