Larynx

larynx

1. LARYNX Dr. Prabhakar Yadav Associate Professor (MBBS, MS) Department of Human Anatomy BPKIHS, Dharan, Nepal

2. Organ for production of voice or phonation. F unctions: Phonation. 2. Respiration. 3. Protection. 4. Deglutition . Acts as a sphincter at the inlet of lower respiratory tract Location: Situated in the anterior midline of the upper part of the neck in front of laryngopharynx . Extent: Root of the tongue to the trachea. 3 rd --- 6 th cervical vertebrae .

3. CARTILAGES: Unpaired cartilages 1.Thyroid 2.Cricoid 3.Epiglottis Paired cartilages 1.Arytenoid 2.Corniculate 3.Cuneiform principal cartilages : Thyroid , cricoid & arytenoids

4. Thyroid cartilage : Two quadrilateral laminae, which meet in Thyroid angle -Males 90° (Adam’s apple) -F emales 120°. Thyroid notch posterior borders: superior & inferior cornua or horns superior cornua : connected to greater cornua of hyoid bone by lateral thyrohyoid ligament - cartilage triticia ( triticea ) may develop. I nferior cornua : Articulates with the cricoid cartilage - cricothyroid joint

5. Posterior border : conjoined insertion of: 1 . Palatopharyngeus . 2. Salpingopharyngeus . 3. Stylopharyngeus . O blique line : Extends from superior thyroid tubercle in front of the root of the superior cornua to the inferior thyroid tubercle behind the middle of the inferior border P rovides attachment to : 1.Thyrohyoid . 2. Sternothyroid . 3. Inferior constrictor ( thyropharyngeus part) from above downwards and from medial to lateral sides

6. P osterior surface : provides attachment in median plane (from above downward ) to: 1. Thyroepiglottic ligament . 2 . A pair of vestibular ligaments. 3 . A pair of vocal ligaments.

7. Cricoid cartilage : Signet-shaped A nterior arch & p osterior lamina. L ocation : C6 vertebra; completely encircles lumen of larynx. posterior surface of lamina : Median ridge & two depressed areas on each side of the ridge. --Lamina projects upwards behind the thyroid cartilage Articulates with : Arytenoid cartilages - superiorly I nferior cornua of thyroid cartilage articulates at junction of arch and lamina.

8. Epiglottis : Leaf-like E xtends up behind the hyoid bone & base of tongue. Upper end is free & forms upper boundary of the laryngeal inlet. L ower end is connected to angle of the thyroid by thyroepiglottic ligament . Posterior surface presents a tubercle in its lower part. Anterior surface : connected to base of tongue by median & lateral glossoepiglottic folds . D epression on each side of the median glossoepiglottic fold - vallecula .

9. Arytenoid cartilages : Pyramidal: A pex- articulates with corniculate cartilage, Base- articulates with the upper border of the lamina of cricoid T wo processes— M uscular process: projects laterally & backwards Vocal process: projects forwards . Three surfaces --posterior , anterolateral & medial

10. Corniculate cartilages (of Santorini ): C onical nodules Articulate with apices of arytenoid cartilages. Lie in posterior parts of the aryepiglottic folds Cuneiform cartilages (of Wrisberg ): Tiny rod-shaped cartilages Lie in posterior parts of the aryepiglottic folds just above the corniculate cartilages.

11. Laryngeal Joints : CRICOTHYROID JOINT : Plane synovial joint between………………... Movements : 1. Rotatory movement : Thyroid cartilage rotates around a transverse axis. 2. Gliding movement : cricoid glides, to a limited extent, in different directions. Recurrent laryngeal nerve enters the larynx very close to his joint.

12. CRICOARYTENOID JOINT: plane synovial: joint between ………. Movements : 1. Rotatory movement: arytenoid cartilage moves around a vertical axis, thus abducting or adducting the vocal cords . 2. Gliding movement : one arytenoid glides towards other or away from it, thus closing or opening the posterior part of glottis.

13. ARYTENOCORNICULATE JOINT : synovial joint between arytenoid and corniculate cartilages. No functional significance.

14. Laryngeal Ligaments and Membranes EXTRINSIC ligaments and membranes : are outside the inner tube of fibroelastic tissue of laryngeal cavity Thyrohyoid membrane : Thyrohyoid membrane connect ……………………………………. ---is pierced by internal laryngeal nerve & superior laryngeal vessels Median & Lateral thyrohyoid ligaments : L ateral thyrohyoid ligament contains - Triticeal cartilagea ( elastic cartilage). Hyoepiglottic ligament : Connects posterior aspect of hyoid with anterior surface of the upper end of epiglottis . Thyroepiglottic ligament : Attaches lower narrow end of epiglottis to thyroid angle . Cricothyroid ligament : Connects lower border of thyroid cartilage to cricoid cartilage in the midline. Cricotracheal ligament : Connects cricoid cartilage with first tracheal ring .

15. INTRINSIC ligaments and membranes : --are parts of fibroelastic tissue, which forms inner tube of laryngeal cavity outside its mucous lining. Fibroelastic tube is interrupted on each by sinus of larynx . P art a bove sinus - Q uadrate or quadrangular membrane P art below sinus - cricovocal membrane or conus elasticus Cricovocal membrane : E xtends upwards from arch of the cricoid cartilage Upper edge is free & is slightly thickened - vocal ligament Attachment: A nteriorly to posterior surface of the thyroid cartilage Posteriorly to the vocal process of the arytenoid cartilage . Fold of mucous membrane over vocal ligament forms vocal fold . vocal ligament Extends anteroposteriorly from………… to ……………………….. Made up of yellow elastic tissue

16. Quadrangular membrane : Extends from sides of epiglottis to the arytenoids . L ower edge is free &is slightly thickened- vestibular ligament Attachment: Anteriorly to posterior surface of the thyroid cartilage Posteriorly to the lateral surface of arytenoid cartilage. Vestibular ligament : E xtends anteroposteriorly from …………. to …………. M ade up of fibrous tissue

17. MUSCLES: EXTRINSIC : Palatopharyngeus . Salpingopharyngeus . Stylopharyngeus . Thyrohyoid. Sternothyroid . All muscles elevate the larynx except sternothyroid , which depresses the larynx

18. INTRINSIC : Cricothyroid: Posterior cricoarytenoid Lateral cricoarytenoid Transverse arytenoid Oblique arytenoid Aryepiglotticus Thyroarytenoid Vocalis Thyroepiglotticus functions are: (a) open or close the laryngeal inlet, (b) adduct and abduct the vocal cords, and (c) increase or decrease the tension of the vocal cords.

19. Only muscle outside the larynx When sound is about to be produced, it tenses the vocal cord and makes it ready to vibrate like a tuning fork - tuning fork of larynx . Muscle Origin Insertion Nerve supply Cricothyroid Anterolateral part of the arch of the cricoid cartilage Inferior cornua and lower border of thyroid cartilage External laryngeal Nerve T ensing the vocal cord H elps in adduction of vocal cord.

20. Safety muscles of larynx Muscle Origin Insertion Nerve supply Posterior cricoarytenoid Posterior surface of the lamina of cricoid Muscular process of arytenoid recurrent laryngeal Nerve Abduction of vocal cord

21. Muscle Origin Insertion Nerve supply Transverse arytenoid ( Unpaired muscle ) Posterior surface of one arytenoid Posterior surface of another arytenoid recurrent laryngeal Nerve Adduction of vocal cord

22. Muscle Origin Insertion Nerve supply Lateral cricoarytenoid Lateral part of arch of cricoid Muscular process of arytenoid recurrent laryngeal Nerve Adduction of vocal cord

23. Muscle Origin Insertion Nerve supply Oblique arytenoid Aryepiglotticus Muscular process of one arytenoid Apex of the other arytenoid Some fibres are continued as aryepiglottic muscle to the edge of the epiglottis recurrent laryngeal Nerve Closes the inlet of larynx

24. Muscle Origin Insertion Nerve supply Thyroarytenoid Thyroid angle and adjacent Cricothyroid ligament Anterolateral surface of arytenoid cartilage recurrent laryngeal Nerve Thyeoarytenoid : relax vocal cord

25. Muscle Origin Insertion Nerve supply Thyroarytenoid Thyroepiglotticus Thyroid angle and adjacent Cricothyroid ligament Anterolateral surface of arytenoid cartilage Some fibres curve upwards reach edge of epiglottis- thyroepiglottics Some fibres project into vocal fold - vocails recurrent laryngeal Nerve Thyroepiglotticus : open inlet of larynx V ocalis : Tense vocal cord

26. CAVITY: Extent : Inlet of larynx to lower border of cricoid cartilage Two pairs of folds extend from arytenoid cartilage to thyroid cartilage Vestibular folds or false vocal cords . Rima vestibule

27. Vocal folds or true vocal cords: E xtent: thyroid angle to vocal processes of arytenoids . Rima glottides : -Narrowest part of the laryngeal cavity.

28. SUBDIVISIONS OF THE LARYNGEAL CAVITY Vestibule ( supraglottic compartment): Extends from laryngeal inlet to vestibular folds. Ventricle or sinus of the larynx ( glottic compartment ) ( sinus of Morgagni) : Elliptical space between vestibular and vocal folds . Infraglottic compartment: E xtends from vocal folds to lower border of cricoid cartilage

29. SUBDIVISIONS OF THE LARYNGEAL CAVITY Saccule of the larynx: Narrow blind diverticulum of mucous membrane that extends posterosuperiorly between vestibular fold & lamina of thyroid cartilage . --contains mucous glands, whose secretions lubricate the vocal cords.

30. M ucous membrane of the larynx : Over posterior surface of epiglottis, true vocal cords, corniculate and cuneiform cartilages mucous membrane is firmly adherent & loosely attached elsewhere. Laryngeal cavity is lined by ciliated columnar epithelium except A nterior surface & upper half of posterior surface of epiglottis, Upper parts of aryepiglottic folds & V ocal folds which are lined by stratified squamous epithelium

31. If internal laryngeal nerve is damaged, there is anesthesia of the mucous membrane in the supraglottic portion and loss of protective cough reflex thus foreign bodies can readily enter larynx .

32. BLOOD SUPPLY Above the vocal fold: Superior laryngeal artery, a branch of superior thyroid artery ; Superior laryngeal vein--drains into superior thyroid vein Below the vocal fold: Inferior laryngeal artery, a branch of inferior thyroid artery; Inferior laryngeal vein - drains into inferior thyroid vein

33. LYMPHATIC DRAINAGE : A bove the vocal cords: Upper deep cervical lymph nodes. B elow the vocal cords: Lower deep cervical lymph nodes.

34. RIMA GLOTTIDIS AND PHONATION -------Narrowest anteroposterior cleft 24 mm in adult males & 16 mm in adult females. Boundaries Anteriorly: Angle of thyroid cartilage. Posteriorly : Interarytenoid folds of the mucous membrane . On each side: Vocal fold in anterior 3/5 th & vocal process of arytenoid cartilage in the posterior 2/5 th two parts : Intermembranous part: anterior three-fifth, between the vocal cords. Intercartilaginous part : posterior two -fifth , between the vocal processes of arytenoid cartilage

35. During quiet breathing or at rest: intermembranous part-- Triangular intercartilaginous part – Q uadrangular During forced inspiration: both parts- Triangular During phonation or speech: Glottis is reduced to a chink by the adduction of the vocal folds During whispering: Intermembranous part –closed Inter-cartilaginous part --widely open

36. Thank you