Anatomy of Larynx.pptx

The larynx houses the vocal cords, and manipulates pitch and volume, which is essential for phonation. It is situated just below where the tract of the pharynx splits into the trachea and the esophagus.

1. Anatomy of Larynx Dr Mathew Joseph MBBS, MD(AIIMS), BCC(Palliative Medicine) Assistant Professor Department of Anatomy Amala Institute of Medical Sciences, Thrissur

2. Larynx

3. Larynx: A hollow muscula o- ligament ous structure with cartilagenous framework. C avity is continuous below with the trachea, and above opens into the pharynx. V alve (or sphincter) to close the lower respiratory tract (protection) P honation R e s p i ra t i on Deglutition • •

4. Extent : Root of tongue – T rachea Front of 3,4,5,6 cervical vertebrae

5. Three large unpaired cartilages ( C ricoid, T hyroid and E piglottis ) Three pairs of smaller cartilages ( A rytenoid, C orniculate, and C uneiform ) A fibroelastic membrane and numerous intrinsic muscles Laryngeal Cartilages

6. L eaf-shaped cartilage. A ttached by its stem to the posterior aspect of the thyroid cartilage by T hyro-epiglottic ligament . P rojects posterosuperiorly. Its upper margin is behind the pharyngeal part of the tongue. I nferior half of the posterior surface of the epiglottis is raised slightly to form an epiglottic tubercle. Epiglottis

7. L argest of the laryngeal cartilages. F ormed by joining of a right and a left lamina anteriorly as the laryngeal prominence ( Adam’s apple ). W idely separated posteriorly. Thyroid cartilage

8. The angle between the two laminae is more acute in men (90 ) than in women (120 ) so the laryngeal prominence is more apparent in men than women. Thyroid cartilage

9. I nferior of the laryngeal cartilage s and completely encircles the airway. S haped like a ‘signet ring’ with a broad lamina of cricoid cartilage. C6 Foundation stone Cricoid cartilage

10. P yramidal-shaped cartilages . Arytenoid cartilage

11. Base is concave and articulates with the sloping articular facet on the lamina of cricoid cartilarge . Apex articulates with a corniculate cartilage . Medial surface of each cartilage faces the other. Anterolateral surface has two depressions for muscle ( vocalis ) and ligament ( vestibular ligament ) attachment . Arytenoid cartilage

12. Elongated Anterior angle is vocalis process for the vocal ligament attachment. Lateral angle is muscular process for attachment of the posterior and lateral crico-arythenoid muscles. Arytenoid cartilage

13. Corniculate cartilages articulate with the apices of the arytenoid cartilage. Corniculate apices project posteromedially towards each other. Cuneiforms are suspend in the part of the fibroelastic membrane- aryepiglottic membrane.

14. Thyroid, C ricoid and B asal parts of A rytenoid are composed of H yaline C artilage – O ssify after 25 Apex of A rytenoid and A ll other are E lastic C artilage

15. Laryngeal Join ts

16. Crico-thyroid joint The cricothyroid joints enable the thyroid cartilage to move forward and tilt downwards on the cricoid cartilage ( effectively lengthens and puts tension on the vocal ligaments ). Crico-thyroid Joint

17. E nable the arythenoid cartilages to slide away or towards each other and to rotate so that t he vocal process pivot either towards or away from the midline ( abduct and adduct the vocal ligament ). Crico- A retynoid Joint

18. Laryngeal Ligaments

19. Th y r o h y o i d membrane Hy o - e p i g l o tt ic ligament Cri c o tr a ch e a l ligament Upper Quadrangular Ligament Cricothyroid Ligament ( Cricovocal And Cricothyroid Membrane) Extrinsic ligament s Intrinsic ligament

20. Is attached to the arch of cricoid cartilage and extends superiorly - Thyroid cartilage anteriorly and vocal process posteriorly. The free margin of this ligament is thickened to form the vocal ligament, which is under the vocal fold (true ‘vocal cord’) of the larynx. Is also thickened anteriorly in the midline to form a distinct median cricothyroid ligament. Cricothyroid L igament

21. Run between the lateral margin of the anterolateral surface of the arytenoid cartilage on the same side to epiglottis superiorly Its free lower margin is thickened to form the vestibular ligament under the vestibular fold (false ‘vocal cord’). Quadrangular Membrane

22. Vestibular Ligament Vestibular ligament is attached posteriorly to the arytenoid cartilage and anteriorly to the thyroid angle just superior to the attachment of the vocal ligament.

23. Tubular in shape. Lined by the mucosa. Opens superiorly (laryngeal inlet) into the anterior aspect of the pharynx just below and posterior to the tongue. Opens inferiorly into the lumen of trachea. Laryngeal inlet can be closed by downward movement of epiglottis whereas the inferior opening is continuously open. Wall of laryngeal cavity: Lateral wall : aryepiglottic folds. Anterior border : mucosa covering the superior margin of the epiglottis. Posterior border : interarytenoid notch (between the two corniculate tubercles). Cavity of the larynx

24. Two pairs of mucosal fold (vestibular and vocal folds) divide the cavity into three major regions; V e s ti b u le i s ( u p p er c h a m be r ) b et w e e n t he laryngeal inlet and the vestibular ligament. Ventricle (middle chamber) is between the vestibular folds above and the vocal folds below. I n fr a g l otti c s p ac e ( i n f e rio r c ha mb e r ) i s be t w een the vocal folds and the inferior opening of the larynx . Laryngeal Cavity

25. P roduce an expanded trough-shaped space . Larygeal saccule is an elongate tubular extension of each ventricle projects anterosuperior between the vestibular fold and thyroid cartilage. Within the walls of the saccule are numerous mucous glands which secrete the mucus to lubricate the vocal folds . Laryngeal Ventricles and Saccules

26. T riangular-shaped opening. B etween the two adjacent vestibular folds at the entrance to the middle chamber of the laryngeal cavity. Its apex is anterior. Its base is formed by the posterior wall of the laryngeal cavity. Rima Vestibuli

27. B etween the two adjacent vocal folds. S eparates the middle chamber above from the infraglottic cavity below. It base is formed by the fold of mucosa (inter-arytenoid fold) at the bottom of the inter-arytenoid notch. Both the rima glottidis and the rima vestibuli can be opened and closed by movement of the arytenoid cartilages and associated fibro-elastic membrane. Rima Glottidis

28. A djust tension in the vocal ligaments. O pen and close the rima glottidis. C ontrol the inner dimensions of the vestibule. C lose the rima vestibuli. F acilitate closing of the laryngeal inlet. Function of Intrinsic Muscles

29. Acting on the cricothyroid and crico- arytenoid joints. Adjusting the distance between the epiglottis and arytenoid cartilage. Pulling directly on the vocal ligament. Forcing soft tissues associated with the quadrangular membranes and vestibular ligaments toward the midline. Action of Intrinsic Muscles

30. F an-shaped muscles. A ttached to the arch of the cricoid cartilage and to the thyroid cartilage . T wo parts; oblique and straight . Obl i q u e p a r t r u n s i n a p o s t e ri o r direction from the arch of the cricoid cartilage to the inferior horn of the thyroid cartilage. Straight part runs more vertically from the arch of the cricoid cartilage to the posteroinferior margin of the thyroid lamina. Cricothyroid Muscles

31. M ove the cricothyriod joints. P ull the thyroid cartilage forward and rotate it down relative to the cricoid cartilage-lengthen the vocal folds. O nly one intrinsic (lies outside) muscles innervated by the superior laryngeal branches of the vagus nerve (CN X). All other intrinsic muscles are innervated by the recurrent laryngeal branches of the vagus nerves. Cricothyroid Muscles

32. • O riginate from shallow depression on the posterior surface of the lamina of cricoid cartilage. R un superolaterally to converge on the muscular processes of the arytenoid cartilage. A bduction and externally rotate the arytenoid cartilage to open the rima glottidis. I nnervated by R ecurent laryngeal branches of the vagus nerve (CN X). Posterior C rico- A rytenoid M uscle

33. O riginates from the upper surface of the arch of the cricoid cartilage. R uns posterosuperiorly to insert on the muscular process of the arytenoid cartilage. A dduct and internally rotate the arytenoid cartilage- adducted vocal folds with an open air channel posteriorly between adjacent arytenoid cartilages. I nnervated by the R ecurrent laryngeal branches of the vagus nerve (CN X). Lateral Crico- A rytenoid Muscles

34. I s a single muscle. S pans the distance between adjacent lateral margins of the arytenoid cartilages and covers the posterior surfaces of these cartilages. I s innervated by the R ecurrent laryngeal branches of the vagus nerve (CN X). Transverse A rytenoid Muscle

35. Oblique arytenoid muscles Pair of muscles, runs from the posterior surface of the muscular process of one arytenoid cartilage to the apex of the arytenoid cartilage on the other side. Some fibers of this muscle continue laterally around the margin of the arytenoid cartilage and into the aryepiglottic fold to continue as part of aryepiglottic muscle. C an narrow the laryngeal inlet by constricting the distance between the arytenoid cartilage and the epiglottis. I nnervated by the recurrent laryngeal branches of the vagus nerve (CN X)

36. A re elongate muscles lateral to and running parallel with each vocal ligament. A ttaches posteriorly to the lateral surface of the vocal process and adjacent depression on the anterolateral surface of the arytenoid cartilage. I nsert anteriorly along the length of the vacal ligament to the thyroid angle. A djust tension in the vocal folds. I nnervated by the recurrent laryngeal branches of the vagus nerve (CN X). Vocalis

37. A re broad flat muscles lateral to the fibro-elastic membrane of the larynx and the laryngeal ventricles and saccules. R un from a vertical line of origin on the lower half of the thyroid angle and adjacent external surface of the cricothyroid cartilage. Some of the fibers may continue into the aryepiglottic fold and reach part of thyro-epiglottic muscle. Thyro- A rytenoid Muscles

38. I s an elaborate sphincter for the lower respiratory tract. P rovides a mechanism for producing sounds. A djusts the size of the ventricle cavity result from changes in the dimensions of the rima glottidis, rima vestibuli, vestibule, and the laryngeal inlet. This changes result from the muscle actions and laryngeal mechanics. Function s of the Larynx

39. During Quiet Respiration The laryngeal inlet, vestibule, rima vestibule and rima glottidis are open. The arytenoid cartilages are abducted. The rima glottidis in triangular shaped.

40. The arytenoid cartilage are rotated l aterally, mainly by action of the posterior crico-arytenoid m. As a result, the vocal folds are abducted, and the rima glottidis widens into a rhomboid shape, which effectively increases the diameter of the laryngeal airway. During Force Respiration

41. Arytenoid cartilages and vocal folds are adducted and air is forced through the closed rima glottidis. This action causes the vocal folds to vibrate against each other and produce sounds, which can then be modified by the upper parts of the airway and oral cavity. Tension in the vocal folds can be adjusted by the vocalis and cricothyroid muscle. Phonation

42. O ccurs when air is retaind in the thoracic cavity to stablize the trunk, for example during heavy lifting, or as part of the mechanism for increasing intra- abdominal pressure. During effort closure, the rima glottidis is completely closed, as is the rima vestibuli and lower parts of the vestibule. The result is to completely and forcefully shut the airway. Effort Closure

43. During Swallowing The rima glottidis, the rema vestibuli and vestibule are closed and laryngeal inlet is narrowed. The larynx is moved upward and forward causing the epiglottis to swing downward towards the laryngeal inlet. All the actions together prevent solids and liquids from entering into the airway and facilitate their movement through piriform fossa to esophagus.

44. I s a procedure in which a hole is made in the trachea and a tube is inserted to enable ventilation when the foreign body obstruct to the larynx. A small transverse incision is placed in the lower third of the neck anteriorly (at level 2 nd and 3 rd tracheal rings), deviates the strap muscle laterally and divides the isthmus of the thyroid gland. Pateint with long-term tracheostomies are unable to vocalize because no air is passing through the vocal cords. Tracheostomy

45. Superior laryngeal a . O riginates from the S uperior thyroid a. and accompaneis the internal branch of the superior laryngeal nerve through the thyrohyoid membrane. Inferior laryngeal a . O riginates from the I nferior T hyroid branch of thyrocerical trunk, together with the recurrent laryngeal n. Arterial Supply

46. Superior laryngeal veins drain into superior thyroid veins, which in turn drain into the internal jugular vein. Inferior laryngeal veins drain into inferior thyroid veins, which drain into the left brachiocephalic veins. Ve nous drain ageof larynx

47. D rain regions above and below the vocal folds Those above the vocal fold follow the superior laryngeal a. and terminate in deep cervical nodes associated with the bifurcation of the common carotid a. Those below the vocal folds drain into deep nodes associated with the inferior thyroid a. or with nodes associated with the front of the cricothyroid ligament or upper trachea. Lymphatic Drainage

48. Sensory and motor is supplied by 2 branches of vagus nerve: Superior laryngeal nerve Recurrent laryngeal nerve Innervation of Larynx

49. Superior Laryngeal Nerve Originate from the inferior vagal ganglia. Divide into internal and external branches just above the level of the superior horn of the hyoid bone. External branch (external laryngeal br.) decends along the lateral wall of the pharynx to supply and penetrate the inferior c onstrictor of the pharynx and ends by the supplying the cricothyroid muscle. Internal branch (internal laryngeal nerve) passes anteroinferiorly to penetrate the thyrohyoid membrane. (it is mainly sensory and supplies the laryngeal cavity above level of the vocal folds.)

50. Recurrent Laryngeal Nerves • Sensory to the laryngeal cavity below the level of the vocal folds. Motor to all intrinsic muscles of the larynx except for the cricothyroid. Left recurrent laryngeal n. originates in the thorax. Right recurrent laryngeal n. originates in the root of neck. Enter the larynx deep to the margin of the inferior constrictor.

51. Sinus of morgagni [ventricle of larynx] ? Singer’s nodule ? Piriform fossa ?