Larynx

CNMC UG

1. larynx Dr S omnath S aha

2. EMBRYOLOGY The supraglottic larynx is derived from the buccopharyngeal primordium , which develops from the third and fourth branchial arches.

3. EMBRYOLOGY The glottis and subglottis are derived from the tracheobronchial primordium from the sixth branchial arch and are formed by the union of lateral furrows that develop on each side of the tracheobronchial primordium . Therefore the larynx has a dual blood supply and lymphatic drainage.

4. SUBSITES Site Subsite Supraglottis Suprahyoid epiglottis Infrahyoid epiglottis Aryepiglottic folds, right and left (laryngeal surfaces) Arytenoids, right and left Ventricular bands, right and left Glottis True vocal cords, right and left (including the anterior and posterior commissures) Subglottis No separate subsites defined

5. The supraglottis is composed of the suprahyoid and infrahyoid epiglottis (both the lingual and the laryngeal surfaces), aryepiglottic folds (laryngeal surfaces only), arytenoids, and ventricular bands (false vocal cords). The boundary between the suprahyoid and infrahyoid epiglottis is a horizontal plane passing through the hyoid bone. The inferior limit of the supraglottis is a horizontal plane through the lateral margin of the ventricle at its junction with the superior surface of the true vocal cord.

6. The glottis is composed of the true vocal cords (both the superior and inferior surfaces) and includes the anterior and posterior commissures . The inferior boundary of the glottis is a horizontal plane 1 cm inferior to the inferior limit of the supraglottis (defined as the lateral margin of the ventricle at its junction with the superior surface of the vocal cord). The subglottis extends from the inferior limit of the glottis to the inferior edge of the cricoid cartilage

7. LARYNGEAL MEMBRANES Cricovocal membrane: triangular fibroelastic memb —Upper border is free—Stretches between middle of thyroid angle to the VP --forms –VOCAL LIG . Lower border attached to arch of cricoid cartilage—Ant end moves upward & medially to meet its fellow from opposite side CONUS ELASTICUS –resist extra laryn spread of glottic & subglottic ca

8. LARYNGEAL MEMBRANES QUADRANGULAR MEMBRANE Deep to the mucosa of AE fold Not well defined Stretches between epiglottis & arytenoid cartilages. Lowr border forms Vestibular lig –lies in the false cord.

9. CAVITY OF THE LARYNX Ventricle/Sinus of larynx Deep illiptical space betw Vestibular & vocal folds. Extend a short distance above & lateral to vestibular folds Saccule –a mucous diverticulum from ant part of ventricular cavity extend upwords betw VF & Thyroid lamina--- Laryngocele Absence of QM &CVM.

10. COMPARTMENTS OF LARYNX - contd Pre Epiglottic Space Of Boyer . ANT – Thyrohyoid membr & Thyroid cartilage above the thyroepiglottic ligament. Superiorly hyoepiglottic lig &mucosa of vallecula Posteriorly infrahyoid epiglottis & thyroepiglottic lig . laterally, the PES is open and continuous with each of the two PGSs

11. The PES contains fat and areolar tissue [7] and is frequently invaded by tumors because the cartilage of the epiglottis has multiple small fenestrations through which cancers arising from the infrahyoid epiglottis may pass. Superiorly, the hyoepiglottic ligament provides a barrier to spread of tumor to the tongue base (Fig. 107-3). The lymphatics of the PES drain through the thyrohyoid membrane, spreading to lymph nodes on both sides of the neck, primarily in zones II and III (Fig. 107-4). [5] Supraglottic tumors with PES involvement are staged as T3 lesions.

12. Transglottic tumour a tumor that crosses the ventricle in a vertical direction Tumors can become transglottic in four ways: by crossing the ventricle directly; by crossing at the anterior commissure ; by spreading through the paraglottic space; and by spreading along the arytenoid cartilage posterior to the ventricle