Physiology of pharynx

for MBBS students

1. Physiology of pharynx Dr Manpreet Singh Nanda Associate Professor ENT MMMC& H Solan

2. Functions of Pharynx Deglutition Respiration Vocal resonance Secretion of mucus by mucous memebrane to lubricate the pharynx Provides drainage to nose, oral cavity, middle ear

3. Functions of Nasopharynx Airway for passage of air into larynx, trachea and lungs Hearing – middle ear ventilation, maintains air pressure Resonance for voice production Drainage for nasal and nasopharyngeal secrtetions Prevents aspiration (Nasopharyngeal isthmus closes during, swallowing, vomiting, speech..

4. Functions of Oropharynx Common conduit for air and food Deglutition Vocal resonance Taste sensation (tongue base, soft palate, anterior pillar, posterior pharyngeal wall) Local defence and immunity ( Waldeyer’s ring)

5. Functions of tonsils and adenoids Immunity against bacteria, virus.... By T Lymphocytes in parafollicular region Barrier to infection (protective sentinels) Ig A antibody production by B Lymphocytes in follicles First 5 years life later atrophy

6. Functions of Laryngopharynx Common conduit for air and food Voice resonance Deglutition

7. Deglutition Process of propulsion of bolus of food from oral cavity into stomach through oropharynx controlled by neuromuscular activity It also disposes dust and bacteria laden mucus Causes pharyngeal opening of E.T to establish equal pressure on both sides of T.M Phases – 1. Oral – voluntary – 1 second 2. Pharyngeal – both – 1 second 3. Oesophageal – involuntary – 8 to 20 second.. Swallowing center in Medulla near nucleus of Vagus N

8. Oral Phase Food chewed Lubricated with saliva Converted into bolus Held between tongue and palate Tongue elevated against palate ( myelohyoid ) Food propelled into oropharynx VOLUNTARY 1 SECOND

9. Pharyngeal Phase Reflex actions 1. 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 oesophagus MIXED PHASE 1 SECOND NOTE – During swallowing rise in pressure of 40 mm Hg pressure at pharyngo oesophageal junction which falls leading to relaxation of sphincter and it opens.

10. Oesophageal Phase Closure of cricopharyngeal sphincter Primary peristalsis of oesophagus (contraction of circular muscles) Food moves down Relaxation of gastro oesophageal sphincter and opens (X CN) Food enter stomach Sphincter closes Note –Secondary peristalsis is due to oesophageal distension ( aeurbachs plexus) INVOLUNTARY 8 – 20 SECONDS

11. NEURAL CONTROL CN V and XII – Chewing and tongue movement CN VII – Taste ( chorda tympani), Sensory to oral cavity ( Nervus Intermedius ), Motor to Orbicuilaris oris CN IX – Taste, Pharynx CN X – Taste, Larynx, Laryngopharynx

12. Sounds during swallowing Heard by auscultation over neck 1 st Sound – AT COMMENCEMENT Due to fluids acting on post pharyngeal wall...... 2 nd Sound – bubbling or trickling noise After 4 – 10 seconds and continue 2-3 seconds

13. Thirst sensation PHARYNGEAL COMPONENT Dehydration -> 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 intake IV hypertonic saline Intercellular dehydration -> Thirst...... (Hypothalamus)

14. Dysphagia Difficulty 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

15. Oral causes Disorder in mastication – trismus , tumour, TM joint Disorder in lubrication – salivary gland Disorder in tongue mobility – paralysis, ulcer, tumour Trauma, buccal ulcers, infection

16. Pharyngeal causes Neurological – brainstem lesions, multiple sclerosis, myasthenia gravis Muscular – myopathy , hypothyroidism UES dysfunction Structural – malignancy, surgery Inflammatory Spasmodic – tetanus, rabies Paralytic – palatal palsy

17. Oesophageal causes Mechanical obstruction- malignancy , peptic strictures Lumen obstruction – FB, strictures, tumours Wall lesions – oesophagitis Motility disorders – achalasia , diffuse oesophageal spasm, scleroderma

18. External causes Cervical – thyroid, cervical spondylosis , tumours, lymphadenopathy Thoracic – aneurysm of aorta, mediastinal tumours, dysphagia lusoria Abdominal – Hepatic enlargement Dysphagia 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

19. Evaluation History Age – child congenital causes, 20 to 40 yrs achalasia , plummer vinson > 40 yrs Sex – plummer vinson – females Onset – sudden in FB or food impaction, gradually progressive in malignancy, peptic strictures, intermittent in spasms Duration – less in inflammation, more in benign More for liquids – achalasia Solids progressing to liquids – malignancy, strictures Intolerance to acid food and fruit juices – ulcer Hoarseness – laryngeal Regurgitation and heart burn – hiatus hernia Nasal regurgitation – palatal paralysis

20. Aspiration into lungs – laryngeal paralysis Past history – diabetes, diptheria , poliomyelitis, FB ingestion, globus Note – Any elderly > 2 weeks dysphagia – rule out malignancy Plummer 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

21. Physical examination Oral cavity Oropharynx Hypopharynx Larynx Neck Chest Cranial nerves CNS

22. Investigations Pan endoscopy – oesophagoscopy , laryngoscopy , bronchoscopy , nasopharyngoscopy Barium swallow – along with fluoroscopy for malignancy, achalasia , strictures, hiatus hernia X ray Neck – radio opaque FB Chest Xray - CVS, pulmonary, mediastinal diseases CT scan/ MRI – Neck and mediastinum , skull base Blood – haemogram (anaemia) Blood sugar – diabetes Manometry and pH monitoring- GERD, acid induced oesophageal spasms Thyoid scan , angiography

23. Treatment Hydration – IV fluids, ryles tube feed, feeding gastrostomy , jejunostomy Treat the cause Medical treatment for anaemia, inflammation, trauma, aspiration pneumonia Surgical treatment- fracture reduction, resection, dilatation