deglutition
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physiology of deglutition
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deglutition
- 3. INTRODUCTION Deglutition involves co-ordinated activity of muscles of oral cavity, pharynx, larynx & esophagus The whole process is partly under voluntary control & partly reflexive in nature Voluntary control of deglutition involves control of jaw, tongue, degree of constriction & length of pharynx 3
- 4. DEFINITION Complex series of voluntary and involuntary neuromuscular contractions proceeding from the mouth to the stomach & is commonly divided into oropharyngeal & esophageal stages.
- 5. COMPONENTS OF DEGLUTITION Deglution has 3 components Passage of bolus from oral cavity to stomach Protection of airway Inhibition of air entry into the stomach 5
- 7. THEORYOF CONSTANT PROPORTION Describes passage of bolus through upper GIT in three phases ORAL PHASE : voluntary control PHARYNGEAL PHASE : pharynx is activated to propel the bolus ESOPHAGEAL PHASE : by esophageal contraction
- 8. THEORYOF ORALEXPULSION This theory states that “the oral expulsion arising from contraction of tongue & Mylohyoid throws bolus into the stomach”
- 9. THEORYOF NEGATIVE PRESSURE According to this theory : “the tongue is brought forward to create a negative pressure which is accentuated by the descent of the larynx & therefore the food is sucked into the esophagus.”
- 10. THEORYOF INTEGRALFUNCTION This theory is based on myometric & electromyographic studies & considers the act of swallowing as a total dynamic process. • It is the most accepted theory.
- 12. ORAL PHASE Food is prepared for swallowing Tongue plays a vital role Divided into Oral preparatory phase & Oral phase proper Under voluntary control 12
- 13. MASTICATION OR CHEWING CHEWING is a program of mandibular movements patterned in a sequence of distinctive recurring cycles. Co-ordination of chewing process matures at about 4 years of age after the deciduous dentition has fully erupted
- 14. MASTICATORYCYCLE : 1st MOVEMENT THE OPENING MOVEMENT : • Mandible is lowered mainly by gravity • Contraction of anterior belly of Digastric • Jaw is prevented from dropping by gradual relaxation of Temporalis & Masseter • Usually deviates to the non–working side
- 15. THE CLOSING MOVEMENT • Mandible is rapidly raised until trapped food is felt • It swings swiftly & rather widely to the working side • Contraction of Masseter & medial pterygoid muscles • Teeth are brought into initial contact with the food MASTICATORY CYCLE : 2nd MOVEMENT
- 16. THE POWER STROKE : • The food is compressed, punctured, crushed & sheared • The teeth meet in lateral occlusion & then slide into centric relation • There is further contraction of Masseter & Temporalis
- 18. The muscles that play an important role in the process of swallowing includes : • MUSCLES OF THE TONGUE • THE MUSCLES OF THE SOFT PALATE : during swallowing it separates nasopharynx from oropharynx. • THE MUSCLES OF PHARYNX : which helps in passage of bolus to the stomach.
- 19. MUSCLES OF THE TONGUE Retracts & elevates the posterior third of the tongue. Narrows oropharyngeal isthmus. Makes dorsum convex Protrude the tongue. shortens the tongue & makes the dorsum concave. broadens & flattens the tongue. . narrows & elongates the tongue shortens the tongue & makes the dorsum convex
- 20. APPLIEDANATOMY • Injury to hypoglossal nerve produces paralysis of the muscles of the tongue on the side of lesion • In cases of acute glossitis tongue fills the oral cavity & protrudes out of it causing difficulty in mastication • In unconscious patients tongue may fall back & obstruct the air passage. This can be prevented by lying the patient in semi reclined position with head down.
- 21. SOFT PALATE Movable, muscular fold suspended from posterior border of hard palate. It is composed of : • Mucous membrane • Palatine aponeurosis (forms fibrous basis) • Muscles
- 22. MUSCLES OF THE SOFT PALATE
- 23. ORALPREPARATORYPHASE Involves breaking down of food in the oral cavity Food is chewed & mixed with saliva making it into a bolus which can be swallowed The elevators of lower jaw play an important role in bolus preparation 23
- 24. Tongue –helps in bolus formation by the action of its intrinsic muscles which alters its shape. Its extrinsic muscles changes its position within the oral cavity thereby helping in chewing the food by dental occlusion Occlusal action of the lips - seal & prevent the bolus from dribbling out of the oral cavity Buccinator muscle – Push the bolus out of the vestibule into the oral cavity proper
- 25. ORAL PREPARATORY PHASE (CONTD) SALIVARY GLANDS: Salivary glands -ducts – saliva- mouth Saliva contains: Mucin- holds food together. Salivary amylase- starts digesting carbohydrates. Bicarbonates-maintain PH level of saliva & protect teeth. Lysozymes-inhibits bacterial growth. 25
- 26. BOLUS FORMATION Most important function of preparatory phase This involves repeated transfer of food from oral cavity to oropharyngeal surface of tongue Bolus accumulates on the oropharyngeal surface of tongue due to repeated cycles of upward & downward movement of the tongue 26
- 27. ORAL PHASE PROPER The bolus is moved towards the back of the tongue The contraction of soft palate prevents nasal regurgitation The soft palate also prevents premature movement of bolus into the oropharynx Once the bolus is of suitable consistency,the transit from mouth to oropharynx just takes a couple of seconds Tongue & the elevation of the mandible plays a vital role during this Phase.Intrinsic muscles of tongue contracts & reduces its size, while genioglossus muscle elevates the tongue towards the palate. When the mandible is elevated the suprahyoid muscles raises the hyoid bone 27
- 28. PHARYNX • Wide muscular tube situated behind nose, mouth & larynx. • Length = 12 cm. • Width = 3.5 cm & narrows as it goes down. Divided into
- 29. MUSCLES OF PHARYNX • STYLOPHARYNGEUS elevates larynx during swallowing • SALPINGOPHARYNGEUS elevates larynx • PALATOPHARYNGEUS CONSTRICTORS • SUPERIOR CONSTRICTOR Aids soft palate in closing the nasopharynx, propels bolus downwards • MIDDLE CONSTRICTOR propels bolus downwards • INFERIOR CONSTRICTOR propels bolus downwards & forms sphincter at lower end (cricopharyngeus)
- 30. PHARYNGEAL PHASE (PUMPINGACTIONOF TONGUE &HYPOPHARYNGEAL SUCTION) Reflexive & involuntary in nature It just takes a second for the bolus to traverse the pharynx & reach the cricopharyngeal area Contraction of diaphragm is inhibited making simultaneous breathing & swallowing impossible During this stage ,bolus from pharynx can enter into 4 paths: 1. Back to mouth 2. Upwards into nasopharynx 3. forwards into larynx 4. Downwards into esophagus 30
- 31. Back into mouth Position of tongue High intra oral pressure developed by the movement of tongue Upwards into nasopharynx Prevented by elevation of soft palate along with its extension uvula Forwards into larynx Approximation of vocal cord Forward & upward movement of laryx Backward movement of epiglottis to seal the opening of the larynx Temporary arrest of breathing
- 32. FUNCTIONSOFTRIGGERPOINTSINOROPHARYNX Stimulation of trigger points - starts off at the pharyngeal reflexive stage of swallowing Trigger points -present at the faucial arches & mucosa of the posterior pharyngeal wall Trigger points are innervated by IXth CN 32
- 33. Stimulation of these trigger points causes dilatation of pharynx due to relaxation of the constrictors, & elevation of pharynx & larynx due to contraction of longitudinal muscles The pharynx constricts behind the bolus thereby propelling it Contraction of the inferior constrictor moves the bolus towards the oesophagus.
- 34. ESOPHAGEAL STAGE This is purely reflexive & involuntary This phase begins by relaxing the cricopharyngeal sphincter The time taken for esophageal transit is 10-15 seconds Primary / secondary / tertiary peristaltic waves play active roles in this phase 34
- 35. Means a wave of contraction followed by a wave of relaxation of muscle fibres of GIT ,which travel in aboral directon(away from mouth) With this ,contents are propelled down along GIT
- 36. Weaker Waves Controlled by deglutition centre Starts when bolus reaches upper part of esophagus Propels food towards the stomach Initially negative pressure is created in the upper part of esophagus-due to the stretching of closed esophagus by elevation of pharynx But immediately pressure becomes positive
- 37. Arise in esophagus locally due to the distention of upper esophagus by the bolus Produces a positive pressure If primary peristaltic contractions are unable to propel the bolus into the stomach,the secondary peristaltic contractions appear & push the bolus into stomach Eg :cheese Controlled locally by myenteric plexus by releasing Acetyl Choline
- 38. Irregular, non propulsive contractions involving long segments which occur during emotional stress
- 39. Distal 2-5cm of esophagus acts like a sphincter. It is called lower esophageal sphincter When bolus enters this part , the sphincter relaxes , so that the content enter the stomach. Later, the sphincter contracts Relaxation & contraction of sphincter occurs in sequence with the arrival of peristaltic contractions of esophagus
- 40. Beginning of swallowing Initially -Voluntary act……….Later-involuntary act Occurs through reflex action called deglutition reflex
- 41. NEURAL CONTROL
- 42. Initiated when food comes in contact with certain trigger areas like fauces, mucosa of posterior pharyngeal wall Via Glossopharyngeal Nerve to brainstem
- 43. Fourth ventricle in the medulla oblongate of brain Travel through glossopharyngeal & vagus nerves(parasympathetic motor fibers) & reach soft palate ,pharynx & esopahgus Glossopharngeal nerve is concerned with pharyngeal stage of swallowing . Vagus nerve is concerned with esophageal stage
- 44. Reflex causes upward movement of soft palate to close nasopharynx & upward movement of larynx to close respiratory passage so that bolus enters the esophagus
- 45. PHASE OF RESPIRATION & SWALLOWING Swallowing occurs during expiratory phase of respiration This helps in clearing food material left in the vestibule. Thus it should be considered to be a protective phenomenon The rhythm of respiration is reset after a successful swallow 45
- 46. APPLIED PHYSIOLOGY DYSPHAGIA ODYNOPHAGIA GLOBUS HYSTERICUS PHAGOPHAGIA PRESBYDYSPHAGIA VOMITING DEGLUTITION APNEA ASPIRATION CRICOPHARYNGEAL DYSFUNCTION CHOKING ANTIPERISTALSIS GAG REFLEX
- 47. Difficulty in swallowing…….Coexist with heart burn & vomiting Pathophysiology Of Dysphagia Lack of coordination or strength of muscles Or Mechanical obstruction If contractions fail to develop progress ,bolus distends the oesophageal lumen & causes discomfort Low amplitude of 1O& 2O peristaltic activity is insufficient to clear oesophagus as in elderly individuals Mechanical narrowing of oesophageal lumen obstructs passage of bolus despite adequate contractions Abnormal sensory perception in oesophagus may cause sensation of dysphagia even after bolus is cleared
- 49. Is highly integrated & complex reflex invloving both autonomic & somatic neural pathways Synchronous contraction of diaphragm ,intercoastal muscles & abdominal muscles raises intra abdominal pressure & combined with LES –forcible ejection of gastric contents Imp to distinguish between vomiting & regurgitation Associated symptoms: abdominal pain,fever,diarrhoea
- 51. Arrest of breathing during deglutition. Occurs reflexly during pharngeal stage. When bolus is pushed into esophagus from pharynx during pharyngeal stage,there is possibility for the bolus to enter the respiratory passage through trachea...........which may cause choking To prevent this,there is apnea along with approximation of vocal cords , forward & upward movement of larynx & backward movement of epiglottis to close the larynx
- 52. Defined as the inhalation of oropharyngeal or gastric contents into the larynx & lower respiratory tract Aspiration Pneumonitis (Mendelson’s Syndrome) chemical injury caused by the inhalation of sterile gastric contents Aspiration Pneumonia is an infectious process caused by the inhalation of oropharyngeal secretions that are colonized by pathogenic bacteria. Risk Factors For Oropharyngeal Aspiration Elderly, neurologic dysphagia, GERD Poor oral hygiene-colonization by respiratory tract pathogens Silent aspiration is common in stroke. Management : Upper respiratory suction,Antbiotics,ET intubation for airway
- 53. Failure of the tonically contracted upper esophageal sphincter to relax and open when one swallows. Symptoms pills or solid food begin to lodge at the level of the lower part of the larynx. Treatment Resolved through surgical procedure Cricopharyngeal Myotomy
- 54. Mechanical obstruction of the flow of air from the environment into the lungs that prevents breathing Prolonged choking-asphyxa-anoxia-fatal Causes: Foreign body,respiratory disease,compression of laryngopharynx Signs & symptoms Person cannot speak or cry, Violent cough Difficult in breathing ,produce wheezing sounds, Clutches throat If respiration not restored ,then cyanosis Treatment BLS & ALS Heimlich maneuver
- 55. Wave of contraction in digestive tract that moves toward the oral end of tract -regurgitation
- 56. Characteristic changes in the swallowing mechanism of otherwise healthy older adults. AGE ASSOCIATED CHANGES Demonstrate delay in onset of specific pharyngeal events Swallowing is slow Larger duration Upper Esophageal Sphincter opening is delayed Chance of Aspiration-more
- 57. • Painful swallowing • Sensation of a lump lodged in throat • Fear of swallowing as in rabies, tetanus, pharyngeal paralysis due to fear of aspiration
- 58. GAG REFLEX Stimulation of sensitive areas of pharynx, soft palate, uvula, tongue Stimulation of Trigeminal & Glossopharyngeal & Vagus nerves Uncoordinated & spasmodic movements of swallowing muscles Gagging Causes chemical irritants, toxic materials, specific drugs, severe pain, mild stimulation of pharynx etc. Treatment • Removal of factors • Local anesthetic may be used while working • Drugs like atropine along with a sedative may be prescribed • Acupressure
- 59. Plain X-Ray Barium swallow CT & MRI Videofluroscopy STUDY OF SWALLOWING
- 60. PLAIN X-RAY X-RAY SOFT TISSUE NECK Lateral view &AP view LATERAL VIEW(taken in full inspiration with neck extention) Examine patency of airway Examine soft tissues of neck Examine the cervical vertebra Foreign body AP VIEW For glottic & subglottic areas CHEST X-RAY PA View Lateral View
- 62. BARIUM SWALLOW PROCEDURE Patient is given liquid barium(Barium suphate)to swallow while bolus is followed fluroscopically. Look for-Filling defect , Obliterative lesions , Extrinsic compression ADVANTAGES: Inert,Suspendable in water Very minimal absorption in GIT DISADVANTAGES: Outside the lumen of GIT acts as foreign body Contrast leak in mediastinum leads to inflammatory reaction
- 64. AIR CONTRAST OESOPHAGRAM Performed like barium swallow but with addition of effervescent granules to barium Advantages: Better anatomical details especially edge contrast Disadvantages: Irradiation Documented on plain film Normal Fungal Plagues
- 65. VIDEOFLUOROSCOPY Definition Dynamic fluoroscopic imaging procedure that enables visualization of rapid & integrated movements involved in all phases of deglutition Equipment X-Ray screening facility Digital/video recorder with microphone & timer
- 66. CT & MRI CT used to stage the disease in malignant MRI used to detect intracranial lesions and vascular abnormalities DISADVANTAGES Expensive Patient has to be in supine which does not reflect stages of swallowing
- 67. SPECIALTECHNIQUES Manometry Manofluroscopy Direct pharyngoscopy Endoscopy Bolus scintigraphy 24 hr oesophageal ph monitoring
- 68. MANOMETRY Definition Technique used to measure intraluminal pressure & coordination of pressures in 3 regions Lower esophageal sphinchter(LES) Oesophageal body Upper esophageal sphinchter(UES) To assess oesophageal peristalsis & oesophageal motor dysfunction
- 69. MANOFLUROSCOPY Similar to videofluroscopy & manometry Advantages Combines pressure & bolus information simultaneously Disadvantages Not widely used Costly
- 70. DIRECT PHARYNGOSCOPY Done under general anaesthesia Used to visualize the pharynx & upper oesophagus To take biopsy and staging tumors of pharynx & upper oesophagus To examine postcricoid area
- 71. Endoscopy / Fibreoptic Endoscopic Evaluation Of Swallowing (FEES) Done in acute stages of dysphagia,Persistent dysphagia Assesment of pharyngeal and laryngeal anatomy and physiology with normal food and drink Procedure Patient sits upright,nose examined for any septal deviation Decongestants & lubrication of nasal passages along with topical anaesthesia Scope passed between inferior turbinate & floor of nose Examine nasopharynx for nasal reflux, oropharynx and hypopharynx
- 72. BOLUS SCINTIGRAPHY Short lived isoptope mixed with single swallow bolus Gamma camera registers the radiation Bolus transit & aspiration assessed Advantages Aspiration assessed Disadvantages Oropharyngeal anatomy not assessed Cannot perform multiple swallows Technical expertise needed
- 73. ULTRASOUND Submental transducers used to image Structures Mobility of bolus transit Vallecular status Advantages Avoids irradiation Normal food used(no barium) Disadvantages Cannot be used to visualize larynx & pharynx due to skeletal interference Not effective for esophageal phase
- 74. OESOPHAGEAL PH MONITORING 24hrs ambulatory Ph monitoring –reliable for GERD Procedure Proximal probe placed below UES Distal probe placed 5cm above LES(position detected by manometry) Reflux measured along entire length of esophagus Disadvantage Invasive Provokes relux