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5 th seminar by sankar naik ms ENT.pdf
- 1. L A RY N X P RES ENTATI ON B Y D R V S ANK AR NAI K 2nd YEAR ENT P G
- 2. LARYNX DEVELOPMENT OF LARYNX ANATOMY OF LARYNX PHYSIOLOGYOF LARYNX Scientific findings 2
- 3. DEVELOPMENT OF LARYNX Scientificfindings 3
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- 5. Scientific findings 5 •Develops from TR ACHEOBRONCHIAL DIVERTICULUM in ventral wall of primitive pharynx during 4th week just below hypobranchial eminence. • Groove deepens (caudally to cranially) laryngotracheal septum separates Tracheobronchial TUBE from pharynx and oesophagus forming oesophageotracheal septum. • Air way epithelium develops from the ENDODERMAL lining of this tube. • Caudally this tube only form 2 branches leading on to 2 main bronchii and also 2 lung buds develop EM B R ILOGY
- 6. • Hypobranchial eminence: ventral par t caudal par t Epiglottic fold T shaped mesenchymal formed midline epiglottic swelling lateral aryepiglottic fold ary tenoid swelling Laminar epithelium grows ventrally to obliterate the lumen by solid cellular plug The cellular condensation is then followed by central necrosis to form two canals anterior vestibulotracheal canal postrior phyaringo tracheal canal Scientific findings 6
- 7. 8th week angleof vocal cord formed by epithelial and mesodermal mass between the vestibule and the upper trachea 10th week mass split sagittally giving rise to both pairs of vocal cord Any incomplet or complete fusion at this stage can lead to laryngeal web and atresia formed Scientific findings 7
- 8. • The laryngealventricle develops and Lateral fissure around the ary tenoid eminence • The lateral par t forms the saccule of ventricle and its develops the true and false cord separateThe epiglottis is last car tilaginous tissue to develop • Hyoid bone 2nd n 3rd arches • Each primary bronchus divided into 18 to 23 generations • SO THYROID CARTILAGE, EPIGLOT TIS, CRICOTHYROID AND • INFERIOR CONSTRICTOR BY 4th ARCH Sup laryngeal ner ve Scientific findings 8
- 9. • Hypobrachial eminence- epiglottis • 4th arch - Thyroid car tilage • 6th arch all (corniculate (Santorini’s car tilage), cuneiform ( Wrisberg), cricoid, ary tenoids & tracheal car tilages) • • Ex ternal Constrictor– (4th arch) analogous to Inf constrictor & Cricothyroid. • • Internal Constrictor – (5th and 6th arches) analogous to intrinsic muscles of larynx. • Thyroid, cricoid and most of ary tenoid is are Hyaline car tilages whereas tip of ary tenoid and rest all are fibroelastic. • RLN enters the six th visceral arch on each side below 6th aor tic arch ar tery, on left side arch ar tery retains its position as ductus ar teriosus so the ner ve is found below the ligamentum ar teriosum after bir th. • Rt side it lies below 4th arch ar tery which becomes the subclavian ar tery. 9
- 10. Anatomy of larynx •2nd to 4th cer vical ver tebrae in children and 3rd to 6th cer vical ver tebrae in adults from laryngeal inlet to inferior border of cricoid car tilage • 9 car tilages = Cuneiform, corniculate and ary tenoids (ACC Paired) and Thyroid, • cricoid and epiglottis (CET unpaired) • Larynx star ts high up under the tongue in early life and with age assumes an • increasingly lower position in neck. • AP diameter : men 36mm & women : 26mm after puber ty • 10
- 11. Framework of Larynx: The skeletal framework is made up HYOID BONE UNPAIRED CARTILAGE PAIRED CARTILAGE Scientific findings 11
- 12. HYOID BONE • HyoidBone 2nd and 3rd arch • Only bone in body not to be attached to any other bone. Body anteriorly, greater cornu • Posterolaterally, lesser cornu at junc. of both projecting superiorly. Scientific findings 12
- 13. THYROID CARTILAGE • ThyroidCartilage LAMINA Angle 90 degree in men and 120 degree in women. • Lamina prolonged posteriorly upwards as superior cornua and downwards as inferior cornua. • Superior attaches lateral thyrohyoid ligament • Inferior (shorter and thicker) has facet for attachment of Cricoid Cartilage • • Oblique line on ext surface of Lamina from superior thyroid tubercle just infront of root of superior horn to the inferior thyroid tubercle (lower border of lamina) and marks attatchement of Sternothyroid, Inferior constrictor muscles and Thyrohyoid ( S I T ) • • In midline just below thyroid notch on inner aspect attaches Thyroepiglottic ligament and on each side below this attaches vestibular and vocal ligaments 13
- 14. Cricoid cartilage • Deepbroad lamina posteriorly and narrow arch anteriorly, attaches to • inferior cornu of thyroid near junction of arch and lamina • Only complete cartilaginous ring. • Lamina has sloping shoulders for attachment of arytenoids Vertical ridge in midline of • lamina gives attachment to longitudinal muscles of the oesophagus • Entire inner layer lined by mucous membrane 14
- 15. EPIGLOTTIS • Attached tothyroid cartilage just below thyroid notch in midline by • THYROEPIGLOTTIC ligament and to hyoid by hyoepiglottic ligament and projects • upwards behind the tongue and body of hyoid bone. • Preepiglottic space is space between these two (hyoepiglottic and thyroepiglottic • ligaments) • Valleculae is space between tongue and Epiglottis. So epiglottis forms posterior wall of valleculae • Glossoepiglottic folds medial and lateral and 15
- 16. Arytenoid cartilage • Threesided pyramids with forward projection (vocal process) attaches to vocal folds and lateral projection (muscular process) to which is attached posterior and lateral cricoarytenoid • Btw these two processes upper triangular area gives attachment to Vestibular ligament • and lower gives attachment to Lateral cricoarytenoid muscles and also vocalis. 16
- 17. Corniculate cartilage • Cartilageof Santorini • A pair of cartilages articulate with arytenoid cartilage Scientific findings 17
- 18. Cuneform cartilage • Cartilageof wrisburg • A pair of rod shaped cartilages that is situated just in front of corniculate cartilage Scientific findings 18
- 19. JOINTS OF LARYNX •Cricothyroid joint :articulate the inferior cornu of the thyroid cartilage • Movements :transverse axis • Cricoarytenoid joint: • Helping adduction and abduction movements 19
- 20. LIGAMENTS OF LARYNX EXTRENSIC LIGAMENT •Thyrohyoid ligament: thyrohyoid membrane (fibrocartilagenous) reinforced by fibrous cartilage as median thyrohyoid ligament and posteriorly as Lateral thyrohyoid ligament .Memb. pierced by superior laryngeal nerve’s internal branch and sup laryngeal vessels • Cricotracheal ligament is between cricoid and 1st tracheal ring 20
- 21. • INTRINSIC LIGAMENTS •Quadrangular membrane arises from the lateral border of Epiglottis and arytenoid cartilages. Upper memb forms framework of aryepiglottic folds and lower margin is thickened to form the vestibular ligament underlying vestibular fold (false vocal cord) • Cricovocal Ligament / Cricothyroid Ligament Or Conus Elasticus Lower part of • Quadrangular membrane is thickened & has elastic fibres. • Upper Border of this membrane forms true vocal cords • Anteriorly thickening of memb. called cricothyroid ligament. • Fibroelastic membrane divided into upper and lower part by the laryngeal ventricle 21
- 22. MUSCLE OF LARYNX •Intrinsic muscles of larynx are all paired • 1. Posterior cricoarytenoid: opens glottis • 2. Lateral cricoary tenoids : Adducts vocal cords • 3. Transverse ary tenoids (unpaired) : Adducts vocal cords • 4. Oblique ary tenoids : (posterior aspect of muscular process of ary tenoids only but superficial to transverse ary tenoids) • 5. Vocalis / Thyroarytenoid: lies above n lateral to cricovocal ligament/conus elasticus. relaxer • 6. Cricothyroid : Only intrinsic muscle which lies outside car tilaginous framework of thyroid. Cricothyroid muscle dysfunction may be implicated in vocal fold collapse (lengthens the vocal folds i.e. tensor) • 7. Aryepiglotticus : continuation of oblique ary tenoid (weak sphincter of laryngeal inlet) • 8. Thyroepiglotticus : Widens inlet of larynx by pulling aryepiglottic folds slightly apar t 22
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- 26. • Infrahyoid muscles: Thyrohyoid, Sternothyroid, Sternohyoid • Suprahyoid group : GSM D SPS , Geniohyoid, Stylohyoid, Mylohyoid, • Digastric, Stylopharyngeus, Palatopharyngeus and Salpingopharyngeus • Both stylopharyngeus and salpingo elevate larynx whereas palato. Tilts larynx for wards • Closers of laryngeal inlet are aryepiglotticus and Interarytenoid. • PRIMARY ELEVATORS : Stylopharyngeus, Salpingopharyngeus, Palatopharyngeus, • thyrohyoid. • SECONDARY ELEVATORS : GSM D • VOCAL FOLDS are layered structures superficial nonkeratinised stratified squamous • epithelium, underlies lamina propria 3 layers Rienkes space (Gelatin like), • Intermediate (Elastin fibre rich) and deep (Collagen rich layer) forms vocal ligament 26
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- 29. INTERIOR OF THELARYNX • Larynx lined by respiratory epithelium except over vocal cords and par ts of epiglottis which are lined by stratified squamous epithelium • Inlet bounded by • Above and in front by the free margins of the epiglottis • Laterally by the aryepiglottic fold • Posterior by the interary tenoid region 29
- 30. Division of thelarynx • Two fo l ds • 1 : tr u e vo cal co r d • 2 : fal se vo cal co r d • Th r e e par ts • 1 : su pr agl otti s • 2 : gl o tti s • 3 : su bgl o tti s Scientific findings 30
- 31. Supraglottis • Wall formedby quadrangular membrane which ex tends from vestibular fold ligament to aryepiglottic folds • Comprises 1: epiglottis • 2: laryngeal aspects of aryepiglottic fold • 3: ary tenoids • 4: ventricular bands • 5: ventricles 31
- 32. Glottis • Ex tendsfrom the lateral angle of the ventricle to the upper boder of cricoid car tilage • Includes 1: true vocal cords • 2: anterior commissure • 3: posterior commissure Scientific findings 32
- 33. subglottis • E xten ds i n fe r io r to l o we r bo de r o f cr i co i d car ti l age 33
- 34. Compartment of larynx • Preepiglottic space – wedge shaped – • Anterior :thyrohyoid membrane and thyoid car tilage • Posteriorly :Epiglottis • Superiorly :hyoepiglottic ligament (continues laterally with paraepiglottic space) • Inferiorly :thyroepiglottic ligament • Impor tance : ca on laryngeal surface of the infrahyoid epiglottis spread readily in to the space 34
- 35. Paraglottic space • Situatedlateral to ventricle and the glottis • Boundaries • anterolaterally : thyroid car tilage and cricothyroid membrane • superomedially : quadrangular membrane • inferomedially : conus elasticus • posteriorly :pyriform sinus mucosa • • Malignency cause fixation of vocal cord and is conserded as advance stage 35
- 36. Nerve supply • Sensory •SLN: supraglottis and upper surface of vocal cords • RLN: subglottis and lower surface of vocal cords • motor • intrinsic : RLN supply all muscle eccept cricothyroid • cricothyroid ex t branch of SLN • • EXTRINSIC: ansa cer vicalis branch of hypoglossal ner ve • Galen’sanastomosis: direct connection b/w internal laryngeal branch of SLN and RLN 36
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- 38. Blood suply • Laryngealar tery : Superior and inferior thyroid ar teries • Cricothyroid : superior thyroid ar tery • VENOUS : Above vocal fold and below vocal fold drainage. • Superior thyroid drains in internal jugular • INFERIOR THYROID VEIN drain into brachiocephalic vein 38
- 39. Lymphatic drainage • SUPRAGLOT TIS: supply the level II and III neck lymph nodes supply • SUBGLOT TIS :delphian node • GLOT TIS :water shed area poor lymphatic supply 39
- 40. Physiology of Larynx •Protection of lower respiratory tract • Phonation • Respiration: Ref lex adjustments of the glottic apparatus plays a role in the mechanism of respiration which contributes to the regulation acid -base balance • To increase intrathorasic pressure: This is done for fixation of the chest by glottic closure. This is essential for straining, climbing. 40
- 41. Protection of lowerRSP tract • Protection of tracheobronchial tree is facilitated by: • Three -tier' sphincter action • Laryngeal elevation—mylohyoid • Laryngeal tilting — stylopharyngeus • Cricopharyngeal sphincter relaxes • Cough ref lex • Cessation of respiratn 41
- 42. • this isthe most primitive function of the larynx. This protective function is carried out by the closure of the laryngeal inlet that occurs during swallowing by a 'three-tier' sphincter action. • There is closure of the laryngeal vestibule by contraction of the aryepiglottic and the interarytenoid muscles. The ventricular bands approximate which constute the second tier. The third tier is by the adduction of the vocal cords by contraction of the interaryteniod. The epiglot tis plays a negligible role in closure of the laryngeal vestibule. The cough ref lex plays an impor tant role in expelling foreign par ticles entering the Tracheobronchial tree. Scientific findings 42
- 43. phonation • The speechproduction requires respiration, phonation, ar ticulation and resonance.It occurs at the time of expiration when the vocal cords are approximated following adduction and the air escapes through causing vibration of the vocal cords. • These vibratory tones are ar ticulated by various structures in the oral cavity and resonated by the pharynx, nasal/ oral cavity and paranasal sinuses to produce speech. • Thus the larynx conver ts the aerodynamic forces generated by the lungs, diaphragm, chest and abdominal muscles into acoustic energy and allows the inspiratory air to enter lungs by abduction through the action of posterior cricoaryetenoid muscles to prepare the pre -phonatory phase. • During phonatory phase, the vocal cords adduct, by the action of lateral cricoary tenoid muscles and the pulmonary air is forced to pass through to produce vocal note. • The larynx acts during phonation by adjusting the vocal cords precisely to produce the required frequencies for the required length of time. 43
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- 45. • The pitchof the voice is determined by the number of vibrations of the vocal cord per second. • The length and volume are determined by the capacity of the lungs. • The quality of the speech is dependent on the resonators as described. • The ar ticulars of voice include the lips, gums, teeth, tongue, palate and the jaws. • • • Intensity and duration depends on the respiratory bellows and subglottic pressure build up by adduction of the cords. • • Pitch depends on the vibratory mass of vocal folds, laryngeal adductors and tensors • Quality (Timbre) depends on resonators and ar ti -culators. Scientific findings 45
- 46. Theories of Phonation •• Myoelastic-aerodynamic theory • Myoelastic phase: Elasticity of the vocal fold help the close. • Aerodynamic phase: Subglottic pressure force vocal core apar t while Bernoulli effect helps vocal cord close. • • One mass model theory: The myoelastic -aerodynami, theory was improved by adding contribution o vocal tract and its impact on airf low. • • Body-cover theory: The vocalis muscle functions as the body over which the mucous membrane and the lamina propria covers the vocal fold and moves by the expiratory air current 46