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1. ANATOMY OF LARYNX SHRUTIK ASHIYANI

2. Function of larynx protects lower respiratory tract controlled airway generation of high intrathoracic pressure for cough and lifting phonation only in humans

3. EXTENT OF LARYNX LARYNGEAL INLET TO CRICOID CARTILAGE C3 TO C6 AT NEUTRAL VOLUME OF LUNGS AND C2 TO C4 IN CHILDREN LITTLE HIGER IN WOMEN AP DIAMETER :MEN 36MM AMD IN FEMALE 26MM SUPRA GLOTTIS : SUPERIORLY - EPIGLOTTIS AND ARYEPIGLOTTIC FOLD TO ARYTENOID INFERIORLY : FALSE VOCAL CORD GLOTTIS : FOLSE VOCAL CORD TO 1CM BELOW TRUE VOCAL CORD SUBGLTTIS START AT 1CM BELOW VOCAL CORD narrowest part is at the junction of the subglottic larynx with the trachea minimal swelling in the subglottic larynx can cause severe airway obstruction in infants as childrens larynx is funnel shaped in adult narrowest part is glottis

4. EMBRYOLOGY

5. arytenoid swelling on both sides - brochial diverticulum appertur of larynx restored @3 months epiglottis originates by fusion of anterior extention of 4th arches (hypobrachial eminance)indication paired origin and last cartiage to form vocal cord forms at 8th to 10th week. hyoid bone form by 2nd and 3rd arches Caption

6. hypobrachial eminence :- epiglottis 4th arch :- thyroid cartilage 6th arch :- corniculate (santorini’s cartilage) cunieform(wrisberg) cricoid ,arytenoid &tracheal cartilages DEVELOPMENT

7. FRAMEWORK OF LARYNX

8. hyoid 2nd and 3rd arch only bone noth attched to any other bone 3parts - body,greater cornu, lessar cornu

9. thyroid cartilage 2 lemina angle 90 in male , 120 in female 2 cornua superior long and thiner backwards and upwards , inferior short thicker backwards downwards superior attach to thyroid ligament inferior facet for attachment of cricoid cartilage oblique line from superior thyroid tubercle (just infront of root of superior horn) to inferior thyroid tubercle (lower border of lamina) attachment for STERNOTHYROID, INFERIOR CONSTRICTOR MUSCLE and THYROHYOID in midline just below the thyroid notch on inner aspect attach thyroepiglottic ligament and on each side inferior to this attaches vestibular and vocal ligament both vocal ligament meet to form anterior commisure

10. cricoid cartilage only complete cartilagenous ring deep broad lamina posteriorly and narrow arch anteriorly ,attaches to inferior cornu of thyroid near junction of arch and lamina lamina has sloping shoulders for attachment of arytenoids vertical ridge in midline of lamina gives attachment to longitudinal muscle of the oesophagus entire inner layer lined by mucous membrane

11. arytenoids ,corniculate and cunieform 3 sided pyramid in shape with forward prjection(vocal process) attaches to vocal folds and lateral prjection(muscular projection) attaches posterior and lateral cricoarytenoid upper triangular area attachment to vestibular ligament lower triangular area :lateral cricoarytenoid muscle and vocalis apex articulates with corniculate cartilage medial surface mucous membrane forms lateral boundry of posterior glottis and posterior surface covered by transverse arytenoid muscle with corniculate cartilage form sinovial joint ,posterior part of aryepiglottic fold base attaches to cricoid lamina with both rotatory movements and side to side gliding movement posteriro cricoarytenoid ligament prevents forward movement of arytenoid cartilage cunieform are 2 small elongated flakes of fibro cartilages one in each side margins of ary epiglottic fold

12. epiglottis attaches to thyroid cartilage just below thyroid notch in midline by THYROEPIGLOTTIC ligament and to hyoid by hyoepiglottic ligament and projects behind the tongue and body of hyoid bone preepiglottic space-hyoepiglottic and thyroepiglottic ligment Valleculae. Space between tongue and epiglottis

13. Extrinsic ligament Thyrohyoid:-thyrohyoid membrane (fibrocartilagenous)reinforced by fibrous cartilage as median thyrohyoid ligamnet and posteriorly as lateral thyrohyoid ligament These membrane may contain cartilage triticea Pierced by superior laryngeal nerve's internal branch and sup laryngeal vessels Cricotracheal ligament b/w cricoid and 1st tracheal ring

14. INTRENSIC LIGAMENT quadrangular membrane arise from lateral-border of epiglottis and arytenoid cartilage upper membrane framework for aryepiglottic fold lower margin : vestibular ligament cricovocal ligament/cricothyroid ligament /conus elasticus : lower part of quardrangular membrane is thickend and has elastic fibres anterior thickening of this membrane called cricothyroid ligament upper border of this membrane form true vocal cords fibroelastic membrane : divided in to upper and lower part by laryngeal ventricle

15. Vocal fold overlie conus elasticus vocal folds layered structures superficial nonkeratinised stratified sqamous epithelium underlies lamina propria -3 layers rienkes space (gelatin like) intermediate (elastin fibres rich) deep (collagen rich layer) forms vocal ligament ant 3/5th vocal cord is within vocal folds and called intermembranous part of vocal cord posterior 2/5th is called intercartilagenous most of larynx lined by pseudostratified ciliated columnar respiratory type of epithelium mucous membrane lining larynx is closely attached over posterior surface of epiglottis ,corniculate,cunieform and vocal ligaments elsewhere it loosely attached and prone to oedema mucous glands numerous at posterior surface of epiglottis,lower aryepiglotticfolds,saccules saccules’s mucous gland lubricate vocalfolds

16. Intrinsic muscles of larynx are all paired 1. Posterior cricoarytenoid :-opens glottis 2. Lateral cricoarytenoids:-Adducts vocal cords 3. Transverse arytenoids (unpaired):-Adducts vocal cords 4. Oblique arytenoids:-(posterior aspect of muscular process of arytenoids only but superficial to transverse arytenoids) 5. Vocalis / Thyroarytenoid:- lies above n lateral to cricovocal ligament/conus elasticus. relaxer 6. Cricothyroid:-Only intrinsic muscle which lies outside cartilaginous 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 arytenoid (weak sphincter of laryngeal inlet) 8. Thyroepiglotticus:-Widens inlet of larynx by pulling aryepiglottic folds slightly apa MUSCLE OF LARYNX

17. Extransic muscle of larynx Infrahyoid group -Thyrohyoid -Sternothyroid -Sternohyoid Suprahyoid group. - Mylohyoid - Geniohyoid - Stylohyoid - Digastric - Stylopgaryngeus - Palatopharyngeus -Salpingopharyngeus

18. spaces within larynx 1] preepiglottic space wedge shaped Anteriorly thyrohyoid ligament and hyoid bone Posteriorly epiglottis Superiorly hyoepiglottic ligament (continues laterally with paraepiglottic space ) Inferiorly thyroepiglottic ligament 2] paraglottic space Laterally throid cartilage Medially conus elasticlus and quadragular membrane Posterior pyriform fossa mucosa It encompasses laryngeal ventricles and saccules 3] Reinke's space Lies under the epithelium of vocal cord

19. Nerve supply of larynx VAGUS Some fibers of vagus originate in medulla in nucleus ambiguus and some at higer lavel Fibres from upper section of NUCEUS AMBIGUUS join 9th nerve (glossopharygeal) and fibres from inferior portion of nucleus joins ACCESORY NERVE (11) 9 10 11 are intricately related nerves in medulla Vagus has superior and inferior ganglion Vagus nerve leaves the skullbase via the jugular foramen anterior to the jugular vein. The vagus then assumes a more posterior position medial to the jugular vein The vagus nerve has an inferior ganglion also known as the nodose ganglion immideately below the jugular foramen The course taken by the vagus nerve differs between the right and the left sides The left vagus nerve follows the carotid artery into the mediastinum crossing anterior to the aortic arch The anterior bronchoesophageal artery supplys the left vagus nerve

20. Superior laryngeal nerve arises from inferior vagal ganglion (nodose) below the level of jugular foramen and recieves branch from superior cervical sympathatic ganglion It goes behind internal carotid artery to sides of pharynx at level of greater horn of hyoid bone devides into small internal and large external branch

21. Vocal fold have lower sensory innervation 3 branches from internal laryngeal nerve supply vallecula,epiglottis and pyriform fossa also carries affrents for neuromuscular spindles and other streach receptors in the larynx Ends by peircing inferior constrictor and joins the ascending branch of recurrent laryngeal nerve ( galen's anastomosis and is purely sensory

22. Recurrent laryngeal nerve As the vagus nerve exit the medulla ,fibres of the recurrent laryngeal nerve are anteroirly situated in it As the vagus traverses inferiorly ,fibres of the recurrent laryngeal nerve starts to rotate medially until they are untimately separated from vagus nerve Right originates from main trunk of vagus infront of subclavian and left infront of arch of aorta Left more liable to injury Both run in the groove between trachea and oesophagus and divided into anterior and posterior branches before antering the larynx RLN pass deep to lower border of inferior constrictor muscles and enters larynx behind cricothyroid ligament -devides into motor and sensory -- sensory supplies below level of vocal folds and all muscles of larynx by motor Blood supply to the RLN comes from the inferior thyroid artery

23. Laryngeal branches of superior and inferior thyroid arteries Cricothyroid branch of superior thyroid artery Laryngeal arteries 1) superior laryngeal artery : arise from superior thyroid artery passes deep to thyroid muscle and togather with the internal branch of SLN it pierces thyrohyoid membrane to supply larynx 2) inferior laryngeal artery : arises from inferior thyroid artery at lower border of thyroid gland and ascends on the traches with RLN it enters the larynx beneath the lower border of inferior constrictor to supply it 3) cricohyoid artery : passes upper part of cricohyoid ligament to supply larynx Arterial Blood supply

24. Venous drainage Superior laryngeal vein -->superior thyroid vein --> internal jugular vein Inferior laryngeal veins --> inferior thyroid veins --> bracheocephalic vein * some veins --> middle thyroid vein -->internal jugular vein Drainage is above vocalcord below vocal cord Lymphatics Divided into two groups by vocal folds into upper & lower drainage LARYNX ABOVE VOCAL FOLDS – drain by vessels accompanying SL vein --> Upper deep cervical LNs LARYNX BELOW VOCAL FOLDS --> prelaryngeal & pretracheal nodes --> Lower deep cervical nodes The vocal folds have no lymphatics as they are firmly bound down to underlying vocal ligament

25. PHYSIOLOGY OF PHONATION

26. NEUROANATOMY OF PHONATION Phonation is dependent upon the integrated functioning of many elements of the central nervous system and peripheral nervous system There is some evidence that the periaqueductal grey matter (PAG), a region of the midbrain, is a crucial site for mammalian voice production. Seen to be involved in Involuntary & Emotional sound production as well as to generate specific respiratory and laryngeal motor patterns fundamental to human speech and singing. The motor activity for vocalization appears tobe integrated through a projecion from thePAG to a column of neurones, known as the nucleus retroambigualis (NRA). The neural pathways for voluntary vocalization arise in the precentral gyrus of the motor cortex in both cerebral hemispheres, and fibres descend as part of the corticobulbar tract, which is part of the pyramidal system or 'direct activation' tract.

27. VOICING The phonatory process, or voicing, occurs when air is expelled from the lungs through the glottis, creating a pressure drop across the larynx When this drop becomes sufficiently large, the vocal folds start to oscillate. The minimum pressure drop required to achieve phonation is called the phonation threshold pressure, and for humans with normal vocal folds, it is approximately 2–3 cm H2O. The motion of the vocal folds during oscillation is mostly lateral, though there is also some superior component as well. However, there is almost no motion along the length of the vocal folds. The biomechanics of phonation When the larynx is at rest and respiration is quiet,the vocal folds abduct on inspiration and slightly adduct on expiration.

28. INITIATION OF VOICE Immediately before phonation, the vocal folds rapidly abduct to allow the intake of air. Wyke has termed this the 'prephonatory inspiratory phase'. Subsequently Adducted The vocal folds working together,there fore,constitute a vibrator which is activated by the excitor, the exhaled air.

29. THE VIBRATORY CYCLE Each vibratory cycle of the vocal folds consists of three phases: Adduction, Aerodynamic separation and Recoil. Increased subglottic pressure -->Inferior margin separation followed by superior --> vocal folds peel apart -->puff of air released --> negative pressure in glottis (bernaulli effect) --> glottis closes with inferior margin first then superior --> subglottic pressure rises again and again VC separates. During phonation two vibratory phases occur i.e. open and closed phases. The open phase denotes the phase during which the glottis is atleast partially open, while the closed phase denotes the phase when the vocal folds completely occlude the glottic chink. The open phase canbe further divided into opening and closing phases.The opening phase is defined as the phase during which the vocal folds move away from one another, while during the closing phase the vocal folds move together in unison. The vocal folds have to be structurally and functionally symmetrical, at the same level and close rapidly in order that a clear vocal note can be initiated and maintained. Insufficient approximation of the vocal folds (glottal insufficiency) results in air wastage and production of breathy voice.

30. One important physiologic parameter which must be noted during phonation is the mucosal wave. The mucosal wave is an undulation which occur over the vocal fold mucosa. This wave travels in an infero superior direction. The speed of mucosal wave ranges from 0.5 - 1 m/sec. The symmetry of these mocosal waves must also be taken into consideration while studying the physiology of voice production. Any mild assymetry between the two vocal folds must be considered as pathological. The requirements of normal phonation are as follows: 1. Active respiratory support 2. Adequate glottic closure 3. Normal mucosal covering of the vocal cord 4. Adequate control of vocal fold length and tension. Normal vocal folds produce three typical vibratory patterns: 1. Falsetto or LOFT REGISTER 2. Modal voice or MODAL REGISTER 3. Glottal fry or PULSE REGISTER

31. LOFT REGISTER Loft register (or falsetto) covers the highest frequencies of the voice. The vocal folds are lengthened, extremely tense and thinned so that there is minimal vibration. The knife-thin free edges are almost adducted and subglottic air pressure is high. During the production of these high frequencies, the larynx is raised by the suprahyoid muscles and the pharynx is shortened. In Modal voice complete glottic closure occurs. This occurs in a majority of mid frequency range voice. During this modal voice production the vocal fold mucosa vibrates independently from the underlying vocalis muscle. This is the basic frequency at which a person phonates. The modal frequency in adult males is 120 Hz while in adult females it is 200 Hz. Pulse register (or glottal fry, vocal fry or creaky voice) occurs during the lowest vocal frequencies and is a feature of normal speech. This terminology reflects the pulsatile nature of the laryngeal sound generated. There is a long closed phased in each vibratory cycle. THEORIES There are currently two main theories as to how vibration of the vocal folds is initiated: THE MYOELASTIC THEORY AERODYNAMIC THEORY A third theory, the NEUROCHRONAXIC THEORY, was in considerable vogue in the 1950s, but has since been largely discredited. These two theories are not in contention with one another and it is quite possible that both theories are true and operating simultaneously to initiate and maintain vibration.

32. THE MYOELASTIC THEORY The myoelastic theory states that when the vocal cords are brought together and breath pressure is applied to them, the cords remain closed until the pressure beneath them—the subglottic pressure—is sufficient to push them apart, allowing air to escape and reducing the pressure enough for the muscle tension recoil to pull the folds back together again. Pressure builds up once again until the cords are pushed apart, and the whole cycle keeps repeating itself. The rate at which the cords open and close—the number of cycles per second—determines the pitch of the phonation. AERODYNAMIC THEORY The aerodynamic theory is based on the Bernoulli energy law in fluids.The theory states that when a stream of breath is flowing through the glottis while the arytenoid cartilages are held together by the action of the interarytenoid muscles, a push-pull effect is created on the vocal fold tissues that maintains self-sustained oscillation. The push occurs during glottal closing,when the glottis is convergent, whereas the pull occurs during glottal opening, when the glottis is divergent. During glottal closure, the air flow is cut off until breath pressure pushes the folds apart and the flow starts up again, causing the cycles to repeat.

33. NEUROCHRONAXIC THEORY This theory states that the frequency of the vocal fold vibration is determined by the chronaxy of the recurrent nerve, and not by breath pressure or muscular tension.

34. Thank you