The larynx is located in the neck below the tongue and hyoid bone. It contains cartilages including the thyroid, cricoid, arytenoid, corniculate, and cuneiform cartilages. The larynx provides protection for the airway and is involved in voice production. It has three regions - the vestibule, middle region, and lower region. The vocal folds within the larynx open and close during breathing and phonation. Nerve supply and blood flow to the larynx allow it to carry out its protective and phonatory functions.

1. The Larynx

2. Larynx -organ that provides a protective sphincter at the inlet of the air passages -responsible for voice production -opens above into the laryngopharynx, and below with the trachea -covered in front by the infrahyoid strap muscles and at the sides by the thyroid gland

3. Location -situated below the tongue and hyoid bone, between the great blood vessels of the neck -lies at the level of the 4 th , 5 th , and 6 th cervical vertebrae

4. Cartilages of the Larynx Thyroid Cartilage -largest -consists of 2 laminae of hyaline cartilage -posterior border extends upward into a superior cornu and downward into an inferior cornu

5. Cricoid Cartilage -formed of hyaline cartilage -shaped like a signet ring -lies below the thyroid cartilage

6. Arytenoid Cartilages - paired, pyramid-shaped cartilages -located at the back of the larynx -articulate with the upper border of the lamina of the cricoid cartilage

7. -Each cartilage has: • apex- articulates with the small corniculate cartilage • vocal process - projects forward and gives attachment to the vocal ligament • muscular process - projects laterally & gives attachment to the posterior and lateral cricoarytenoid

9. Corniculate Cartilages -paired conical cartilages -gives attachment to the aryepiglottic fold

10. Cuneiform Cartilages -paired, small rod-shaped cartilages -found in the aryepiglottic folds

12. Epiglottis -leaf-shaped lamina of elastic cartilage lies behind the root of the tongue Attachments: stalk - back of the thyroid cartilage sides - arytenoid cartilages by the aryepiglottic folds of mucous membrane upper edge - free The covering of mucous membrane passes forward onto the posterior surface of the tongue as the median glossoepiglottic fold Vallecula - depressions on each side

14. Membranes and Ligaments of the Larynx Thyrohyoid membrane -connects the upper margin of the thyroid cartilage to the hyoid bone -midline is thickened to form the median thyrohyoid ligament -pierced on each side by the superior laryngeal vessels and internal laryngeal nerve from superior laryngeal nerve Cricotracheal Ligament -connect the cricoid cartilage to the first ring of the trachea

15. Quadrangular Membrane - extends between the epiglottis and the arytenoid - thickened inferior margin forms the vestibular ligament - the vestibular ligaments form the interior of the vestibular folds

16. Cricothyroid Ligament • Lower Margin -attached to the upper border of the cricoid cartilage • Superior Margin -ascends on the medial surface of the thyroid cartilage -upper free margin composed of elastic tissue which forms the important vocal ligament on each side anterior end - thyroid cartilage posterior end - arytenoid cartilage -vocal ligaments form the interior of the vocal folds (vocal cords)

18. Inlet of the Larynx (Laryngeal aditus/Laryngeal aperture) -opening is wider in front than behind Boundaries: • Anterior- Epiglottis • Lateral- Aryepiglottic fold • Posterior- Arytenoid cartilages & Corniculate cartilages

20. Piriform Fossa -recess on either side of the fold and inlet Boundaries: Medial- Aryepiglottic fold Lateral- Thyroid cartilage & Thyrohyoid membrane

21. Laryngeal Folds Vestibular Fold -fixed fold on each side of the larynx -formed by mucous membrane covering the vestibular ligament -vascular and pink in color

22. Vocal Fold (Vocal Cord) -mobile fold on each side of the larynx -concerned with voice production -formed by mucous membrane covering the vocal ligament -avascular and white in color

23. Boundaries: Medial- Aryepiglottic fold Lateral- Thyroid cartilage & Thyrohyoid membrane

24. -moves with respiration • Rima glottidis/glottis - gap between the vocal folds; narrowest part of the larynx and measures about 2.5 cm from front to back in the male adult and less in the female. In children, the lower part of the larynx within the cricoid cartilage is the narrowest part

25. Boundaries: Anterior- Vocal Folds Posterior- Arytenoid cartilages

26. Cavities of the Larynx -extends from the inlet to the lower border of the cricoid cartilage divided into three regions: • vestibule - between inlet and vestibular folds • middle region - between vestibular folds above and vocal folds below • lower region - between vocal folds above and lower border of the cricoid cartilage below

27. Sinus of the Larynx - paired small recesses lined with mucous membrane between the vestibular and vocal folds Saccule of the Larynx - a diverticulum of mucous membrane that ascends from the sinus; mucous secretion lubricates the vocal cords

28. Muscles of the Larynx -divided into two groups Extrinsic - moves the larynx up and down during swallowing

29. Muscles of the Larynx • Elevation: Digastric Stylohyoid Mylohyoid Geniohyoid Stylopharyngeus Salpingopharyngeus Palatopharyngeus • Depression: Sternothyroid Sternohyoid Omohyoid

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33. Movements of the Vocal Folds with Respiration Quiet inspiration -vocal folds are abducted and glottis is triangular Expiration -vocal folds are adducted Deep inspiration - vocal folds are maximally abducted and glottis is diamond shaped because of the maximal lateral rotation of the arytenoid cartilages

34. Sphincteric Function of the Larynx -two sphincters in the larynx sphincter at the inlet is used only during swallowing epiglottis - serves as a cap over the laryngeal inlet rima glottidis serves as a sphincter in coughing or sneezing intrathoracic pressure rises; vocal folds are suddenly abducted; Valsalva maneuver , forced expiration takes place against a closed glottis

35. Voice Production in the Larynx - intermittent release of expired air between the adducted vocal folds results in their vibration and in the production of sound Frequency/pitch - length and tension of the vocal ligaments Quality - resonators above the larynx, namely, the pharynx, mouth, and paranasal sinuses; it is controlled by the muscles of the soft plate, tongue, floor of the mouth, cheeks, lips, and jaws

36. Voice Production in the Larynx Speech - intermittent release of expired air between the adducted vocal folds Singing - prolonged release of the expired air between the adducted vocal folds Whispering - the vocal folds are adducted, but the arytenoid cartilages are separated

37. Mucous Membrane of the Larynx Cavity – lined by ciliated columnar epithelium Vocal cords – lined by stratified squamous epithelium

38. Nerve Supply of the Larynx Sensory Nerves Above the vocal cords: internal laryngeal branch of the superior laryngeal branch of the vagus nerve Below the level of the vocal cords : recurrent laryngeal nerve Motor Nerves All: recurrent laryngeal nerve except cricothyroid muscle which is supplied by external laryngeal branch of the superior laryngeal branch of the vagus nerve

40. Blood Supply of the Larynx Upper half of the larynx: superior laryngeal branch of superior thyroid artery Lower half of the larynx: inferior laryngeal branch of inferior thyroid artery - deep cervical lymph nodes Lymph Drainage of the Larynx

41. Lesions of the Laryngeal Nerves Involves recurrent laryngeal nerves and external laryngeal nerve which are vulnerable during operations on the thyroid gland left recurrent laryngeal nerve may be involved in a bronchial or esophageal carcinoma or in secondary metastatic deposits in the mediastinal lymph nodes Clinical Notes

42. right and left recurrent laryngeal nerves may be damaged by malignant involvement of the deep cervical lymph nodes Section of the external laryngeal nerve - weakness of the voice because the vocal fold cannot be tensed. The cricothyroid muscle is paralyzed Unilateral complete section of the recurrent laryngeal nerve - Speech is not greatly affected - Bilateral complete section of the recurrent laryngeal nerve - Breathing is impaired; speech is lost Clinical Notes Cricothyroidotomy - primary purpose is to provide an emergency breathing passage for a patient whose airway is closed by traumatic injury to the neck.

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44. Edema of the Laryngeal Mucous Membrane - accumulation of tissue fluid causes the mucous membrane above the rima glottidis to swell and encroach on the airway. In severe cases, a cricothyroidotomy or tracheostomy may be necessary.