Anatomy of larynx

Anatomy of larynx

1. ANATOMY OF LARYNX Dr. Jinu Department of ENT

2. The larynx extends from the laryngeal inlet to the inferior border of the cricoid cartilage.

3. Larynx lies opposite the third to sixth cervical vertebrae, being a little higher in women than in men . The infantile larynx is proportionally smaller and is more funnel shaped.

4. Measurements Until puberty there is little difference b/w male & female larynx. After puberty:- Male larynx undergoes considerable increase In Males In Females Length  44 mm 36 mm Transverse diameter 43 mm   41mm A-P diameter  36 mm 26 mm Circumference 136 mm 112 mm

5. The framework of the larynx • Hyoid bone 9 Cartilages: – Connected by • Joints • Ligaments • Membranes Moved by • 8 Muscles(Intrinsic) • Cavity – Mucous membrane

6. Cartilages 3 Paired • Arytenoid • Corniculate • Cuneiform 3 Unpaired • Thyroid • Cricoid • Epiglottis

7. HYOID BONE U-shaped bone

8. Thyroid Cartilage Shield shaped, open posteriorly , angulated anteriorly Largest cartilage of larynx Protect larynx Provide an attachment to vocal cords

9. The lateral thyrohyoid ligament connects the tip of the superior cornua of the thyroid cartilage to the posterior ends of the greater cornua of the hyoid. The ligaments often contain a small nodule of cartilage, the cartilago triticea

10. On the external surface of each lamina, an oblique line curves downwards and forwards from the superior thyroid tubercle, situated just in front of the root of the superior horn, to the inferior thyroid tubercle on the lower border of the lamina. This line marks the attachment of the Thyrohyoid, Sternothyroid Inferior constrictor muscles.

11. A vertical ridge in the midline of the lamina gives attachment to longitudinal muscle of the oesophagus and produces a shallow concavity on each side for the origin of the posterior cricoarytenoid muscle . The entire inner surface of the cricoid cartilage is lined with mucous membrane .

12. Of laryngeal inlet

13. Hyoepiglottic ligament divides epiglottis into Suprahyoid Epiglottis Infrahyoid Epiglottis

14. Lateral

15. Pre- epiglottic space of Boyer Anterior surface of infrahyoid epiglottis is separated from thyrohyoid membrane and thyroid cartilage by fat filled pre- epiglottic space. Pre- epiglottic space invaded by carcinoma of supraglottic larynx and the base of tongue.

16. Boundaries Anterior: Upper part of thyroid cartilage and thyrohyoid membrane. Superior: Hyoepiglottic ligament. Posterior: Infrahyoid epiglottis. Inferior: Thyroepiglottic ligament. Communication: Laterally it is continuous with paraglottic space.

17. Thyroid Hyaline Cartilage Cricoid May ossify after 20 Arytenoids yrs (Male)( T→C→A ) (Except its tip) complete by 65yrs. Epiglottis Fibroelastic Corniculate They do not ossify Cuneiform Tip of Arytenoid

18. Arytenoid Gliding -medially & Laterally closing and opening the post part of glottis

19. MEMBRANES & LIGAMENTS Extrinsic Intrinsic Thyrohyoid Quadrangular membrane Cricotracheal vestibular ligament Hyoepiglottic Crico -vocal membrane & vocal ligament

20. Thyrohyoid membrane median thyrohyoid ligament 2lateral thyrohyoid ligament superior cornua of the thyroid cartilage to the posterior ends of the greater cornua of the hyoid . Small nodule of cartilage , CARTILAGO TRITICEA

21. Epiglottic cartilage to the body of hyoid bone Lower border of cricoid cartilage to 1 st tracheal ring

22. Intrinsic Part of Fibro-elastic Membrane which lies beneath the mucous membrane of the larynx. The fibro-elastic membrane is divided into an upper and lower part by the laryngeal ventricle.

23. Cricovocal membrane

24. & Cricothyroid membrane

25. Quadrangular membrane

26. Laryngeal Cavity From Inlet of Larynx to Lower border of Cricoid Cartilage (Lower border Of 6 th cervical vertebra)

27. Vestibule: This region lies between the laryngeal inlet and vestibular folds. Boundaries : Anterior wall : Posterior surface of epiglottis. Lateral sides : - Aryepiglottic folds . Posterior wall : -Arytenoids .

28. contains vestibular ligament, a few fibres of thyroarytenoideus muscle and mucous glands. (true vocal cords).

29. Broyle’s ligament

30. Ventricle (Sinus of larynx) / sinus of Morgagni : This deep elliptical space lies between vestibular and vocal folds.

31. The submucosa of the ventricle contains numerous seromucinous glands. The secretions produced by these exocrine glands provide both mechanical and immune ( lysozyme ) protection for the vocal folds.

32. Laryngeal saccule / S accule of Hilton At the anterior end of the ventricle is a diverticulum The saccule (of Hilton) is lined with mucous glands, which are thought to lubricate the vocal folds

33. Abnormal dilatation of the saccule results in an air-filled laryngocele that should be distinguished from a mucocele of the saccule ( saccular cyst ), which lacks free communication with the ventricle not air filled

34. CT shows laryngocele

35. most of the laryngeal foreign bodies are seen in supraglottic region lying above the vocal cords. Subglottic region ( Infraglottic larynx) : Extends from below the vocal cords to lower border of cricoid cartilage.

36. Glottis ( Rima glottidis ): This narrowest part of an adult laryngeal cavity lies between vocal cords and arytenoids of the two sides.

37. Anteroposterior length of glottis is men (24 mm) women (16 mm).

38. Pyriform fossa

39. SpACeS of the LARynx Pre- epiglottic space of Boyer:

40. Pre- epiglottic space of Boyer Pre- epiglottic space can be invaded by carcinoma of supraglottic larynx and the base of tongue.

41. Paraglottic space l Tuckers Space: It communicates with pre- epiglottic space ( Anteriorsuperioly ) Boundaries: Laterally : Thyroid cartilage and cricothyroid membrane. Medial : Conus elasticus , Ventricle and quadrangular membrane. Posterior : Anterior mucosa of pyriform fossa.

42. Paraglottic space l Tuckers Space: Growths invading paraglottic space destroy cricothyroid Membrane Ventricle tumors -> spread transglottically Vocal cord tumors involving thyroarytenoid muscle -> subglottic and extralaryngeal region. Lateral supraglottic tumors can travel to subglottic region ->the inner surface of thyroid. Pyriformfossa tumor ->into endolarynx and fix vocal folds

43. Reinke’s space This potential space has scanty subepithelial connective tissues and lies under the epithelium of vocal cords. It is bounded by– Above and below: Arcuate lines. Anterior: Anterior commissure . Posterior: Vocal process of arytenoids .

44. Layered structure of the vocal fold Lamina Propria - 3Layers Superficial-fibrous Substance( Reinkes space) Intermediate –elastic Deep – Collagen fibres VOCAL LIGAMENT formed By Intermediate and deep layer Body contain Vocalis muscle

45. muSCLeS of LARynx There are two types of laryngeal muscles intrinsic ( connecting laryngeal cartilages to each other) extrinsic ( connecting larynx to the surrounding structures).

46. Intrinsic muscles They are further divided into two: 1) muscles acting on vocal cords 2 ) muscles acting on laryngeal inlet. Vocal cords Abductors: Posterior cricoarytenoid Adductors: Lateral cricoarytenoid Interarytenoid (transverse and oblique arytenoids ) Thyroarytenoid (external part) Tensors: Cricothyroid Relaxers: Vocalis & Thyroarytenoid internal part

47. Cricothyroid Action: lengthens vocal folds(tensor) Nerve(motor supply) : Supplied by the external laryngeal nerve,a branch of superior laryngeal nerve.

48. Posterior cricoarytenoid Action: Abduction of Vocal Cord

49. Interarytenoid Transverse interarytenoid Action : Adducts vocal folds oblique interarytenoids Action : Closes laryngeal inlet

50. Thyroarytenoid – Internal part ( Vocalis ) Action : Shortens vocal folds & thickness

51. Relaxers of VC: Vocalis and thyroarytenoid

52. Laryngeal inlet Openers: Thyroepiglottic ( part of thyroarytenoid ) Closers : Interarytenoid ( oblique part) Aryepiglottic ( posterior oblique part of interarytenoid )

53. ( 1) digastric , (2) stylohoid , ( 3) mylohyoid , (4) sternocleidomastoid , (5) thyroidhyoid , ( 6) sternothyroid , (7) cricothyroid , (8) sternohyoid and ( 9) omohyoid Omohyoid

54. Extrinsic muscles: Secondary elevators: They are attached to the hyoid bone Mylohyoid (main ) Digastrics Stylohyoid Geniohyoid .

55. Lymphatic Drainage

56. EMBRYOLOGICAL DEVELOPMENT Structure Source laryngeal mucosa Endoderm of cephalic part of foregut laryngeal cartilages mesenchyme Epiglottis Hypobranchial eminence Upper part of body of hyoid bone Lesser cornua of hyoid bone Stylohyoid ligament 2nd branchial arch Lower part of body of hyoid bone and greater cornua 3rd branchial arch

57. Upper part of thyroid cartilage 4th branchial arch lower part of thyroid cartilage, cricoid , corniculate , and cuneiform 6 th arch cartilages Intrinsic muscles of larynx 6th branchial Arch

58. Infant Larynx VS Adult Larynx Infant Larynx Adult Larynx higher in the neck Voca lcords lie at C3/C4 level During swallowing go up to C1/C2 level. Low Vocal cords lie at C5 level . Laryngeal cartilages are soft and collapse easily. Cartilage undergo ossification Epiglottis : omega shaped & Floppy Firm and flatter Arytenoids: large Thyroid: flat. Cricoid : The diameter of cricoid is smaller than glottis subglottis is the narrowest portion Glottis is the narrowest portion Cricothyroid and thyrohyoid spaces: They are very narrow

59. Infant Larynx Adult Larynx Size: smaller and has a narrower lumen. Wider lumen Shape: It is conical and funnel-shaped column shaped Submucosal tissue: It is thick and loose and becomes easily edematous in response to trauma or inflammation

60. Infant Adult

61. Adult Larynx Infant Larynx

62. Applied anatomy

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