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Principles and embryology ANATOMY OF LARYNX.pptx
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- 2. General Description. Larynx extendsfrom laryngeal inlet to the lower border of cricoid cartilage. At rest, the larynx lies opposite the third to sixth cervical vertebrae in adult males; it is somewhat higher in children and adult females A-P diameter is about -36mm (M) -26mm (F)
- 3. Laryngeal framework. Consist of: Hyoid bone Cartilages Ligaments & membrane Extrinsic & intrinsic muscles Lined by mucus membrane Adipose & loose connective tissues filling space
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- 5. Laryngeal Cartilages Paired Arytenoid cartilage Corniculatecartilage Cuneiform cartilage Unpaired: Thyroid cartilage Cricoid cartilage Epiglottis
- 6. Thyroid Cartilage (oblongshield) Shield shaped, open posteriorly, angulated anteriorly Angulation more acute in males(90 d) females(120 d) Its function is to shield larynx from injury and provide an attachment to vocal cords
- 7. This cartilage has2 alae/wing which meet anteriorly, they form a depression called the THYROID NOTCH before meeting at the protruberance of the Adam’s apple or laryngeal prominence. Posterior border of each lamina prolonged above and below to formed superior & inferior cornu Superior cornu-Lateral thyroid ligament attached Inferior cornu- Articulate with cricoid cartilage Ossifies at 20-30 years of age, begins in the inferior margin and progress cranially
- 8. Cricoid Cartilage Signet ringshaped Hyaline cartilage Stronger than thyroid cartilage. Lamina – 2 to 3 cm from above downwards, considerably broader than anterior arch.
- 9. Epiglottis Thin leaf shapedfibro-cartilage, situated in midline Upper free end broad & rounded, projects up behind base of tongue Narrow base called petiole This attachment forms lower limit of pre-epiglottis space
- 10. Attached to theINSIDE of the thyroid cartilage. anteriorly and projects upward and backward above the laryngeal opening. The epiglottis is attached to the hyoid bone by the hyoepiglottic ligament. To the posterior part of the tongue by the median glossoepiglottic fold. To the sides of the pharynx by the lateral glossoepiglottic folds. To the thyroid cartilage by the thyroepiglottic ligament. The mucous membrane covering the epiglottis is reflected to the posterior part of the tongue as one medial and two lateral glossoepiglottic folds. Between these folds are depressions called epiglottic valleculae.
- 11. Half of epiglottis projectsabove hyoid This part has a laryngeal and lingual surfaces
- 12. Infrahyoid portion has nofree anterior surface Forms posterior wall of PreEpiglottic Space Epiglottic cartilage contains many pits filled with mucous glands Little barrier between infrahyoid portion and PES
- 13. Arytenoids Paired cartilages, pyramidal inshape Base articulated with cricoid PCA & LCA muscles attach on muscular process Anterior angle elongated into vocal process which receives insertion of vocal ligament
- 14. Corniculate Cartilages Fibroelastic Cartilages ofSantorini Small cartilages above the arytenoid and in the aryepiglottic folds
- 15. Cuneiform Cartilages Firboelastic cartilages Cartilagesof Wrisberg Elongated pieces of small yellow elastic cartilage in the aryepiglottic folds
- 16. Laryngeal Joints Cricothyroid Joint Betweeninferior cornu of the thyroid cartilage and facet on the cricoid cartilage at the junction of the arch and lamina Two movements: Rotation Gliding Cricoarytenoid Joint Between the base of the arytenoid cartilage and the facet on the upper border of the lamina of the cricoid cartilage Two movements: Rotation Gliding
- 17. Ligament & membraneof larynx Extrinsic ligaments/Membranes: Connect laryngeal cartilages to hyoid bone above & trachea below Thyrohyhoid membrane Cricothyroid membrane Cricotracheal membrane Hyoepigloittic ligament Intrinsic ligaments/Membranes: Connect laryngeal cartilage together, Forming internal framework of larynx Crico-vocal membrane (Conus elasticus) Quadrangular membrane
- 18. Extrinsic Ligaments Thyrohyoid membrane piercedon each side by: 1. Superior laryngeal vessels 2.Internal branch of superior laryngeal nerve Median thyrohyoid ligament – thickened median portion Lateral thyrohyoid ligament – thickened posterior border - where cartilago triticea is often found
- 19. Extrinsic Ligaments Cricothyroid membrane and ligaments Maybe pierced for emergency tracheotomy (cricothyrotomy)
- 20. Extrinsic Ligaments Cricotracheal Ligament Attachesthe cricoid cartilage to the first attached ring Hyoepiglottis It connects the epiglottic cartilage to hyoid bone.
- 21. Intrinsic Ligaments Fibroelastic membrane Dividedinto upper and lower parts by the ventricle of the larynx 1) Upper part: Quadrangular membrane Extends between lateral border of epiglottis & arytenoids cartilage Upper margin-Forms aryepiglottic fold Lower margin- Vestibular ligament ( false cord) Forms part of wall between upper pyriform sinus and laryngeal vestibule
- 22. Intrinsic Ligaments 2) Lowerpart(Thicker): Cricovocal membrane or Conus elasticus It attached below to upper border of cricoid cartilage Upper border is free and stretches between midpoint of laryngeal prominence of thyroid cartilage anteriorly & vocal process of arytenoids behind Free upper border constitute vocal ligament (true cord) Anteriorly thickening Cricothyroid ligament- Connects cricoid & thyroid cartilage in midline
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- 24. INTRINSIC LARYNGEAL MUSCLES: •ADDUCTORS: • Lateral cricoarytenoid-contraction of this muscle causes adduction and lengthening of vocal folds. • Thyroarytenoid-forms the main bulk in the vocal folds.It has 2 bellies-internus(referred to as vocalis) and externus(referred to as ventricularis).When it contracts,the vocal folds are shortened and thickened. They are innervated by two different types of nerve fibers; vocalis by “slow twitch” nerve fibres required for phonation and ventricularis by “fast twitch”nerve fibres essential for coughing and rapid protection of airway. • Interarytenoid-contains transverse and oblique fibres.When this muscle contracts,it adducts the vocal folds by rotating both arytenoids medially and causes closure of posterior glottis and narrowing of laryngeal inlet. • ABDUCTORS: • Posterior Cricoarytenoid- sole abductor of vocal folds. Paralysis of the muscle on both sides can therefore lead to respiratory distress due to inability to open up laryngeal inlet for breathing.
- 27. INTRINSIC LARYNGEAL MUSCLES: CRICOTHYROID: •Tensor of the vocal folds. • Two muscle bellies-pars recta(vertical component) and par oblique.
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- 30. Cavity of theLarynx •Two pairs of folds- vestibular and vocal divide the cavity into 3 parts: 1.Vestibule 2.Ventricle 3.Subglottic space
- 31. Cavity of theLarynx Vestibule– boundaries: Anterior: posterior surface of epiglottis Posterior: interval between arytenoid cartilages Lateral: inner surface of aryepiglottic folds and upper surfaces of the false cord
- 32. Cavity of theLarynx Ventricle(sinus of Larynx) Deep elliptical space between vestibular and vocal fold. Saccule – conical pouch at anterior part of the ventricle, lies bet. Inner surface of thyroid cartilage and false cord; has numerous mucous glands open into the surface of its lining mucosa for lubricating the vocal cords.
- 33. Cavity of theLarynx Glottis(rima glottidis) – space between free margin of the true VC, opening/aperture Posterior glottic chink in adult: 18-19mm; New born: 4mm; total glottic chink in a newborn: 14mm2
- 34. Cavity of theLarynx Abduction: Respiration,wide and triangular Adduction: Phonation, slit-like appearance
- 35. Cavity of theLarynx Truecords Voice production Protection of lower respiratory tract Anteriorly,: angle of thyroid cartilage Posteriorly: vocal processes of the arytenoid cartilages Enclose vocal ligament and a major part of the vocalis muscle False Cords (ventricular bands) Anteriorly: angle of the thyroid cartilage Posteriorly: bodies of the arytenoid cartilage
- 36. Supraglottis Consists of ventricles, falsecords, laryngeal surface of epiglottis, aryepiglottic folds and the mucosal expanse. Posterior tapering shape reduces area of mucosa in posterior region So majority of SG tumors are epiglottic
- 37. Glottis Consists of truecords, anterior commissure and posterior commissure Narrow triangular space between the true cords is called rima glottis Anterior 2/3 is membranous Posterior third consists of vocal processes of arytenoids Posterior 1/3 of cords and covering mucosa are called posterior commissure
- 38. Sub-glottis Area at whichlarynx merges with trachea It extend from Inferior border of vocal fold to inferior margin of cricoid. Cricoid cartilage is involve early because of the absence of an intervening muscle layer in ca. subglottic.
- 39. Pre-Epiglottic Space Bound supby hyo-epiglottic ligament, ant by thyrohyoid memb. & thyroid cartilage and posteriorly by epiglottis Filled with fat and areolar tissue Continuous with para-glottic space Cx of laryngeal surface of epiglottis readily spread to PreEpiSpace
- 40. Paraglotticspace: Bounded: Laterally: Thyroid cartilage Medially:Conus elasticus,quadriangular membrane Posteriorly:Pyriform fossa mucosa It encompasses laryngeal ventricles & saccules Growths which invade this space can present in the neck through cricothyroid space
- 41. Reinke’s Space Mucosa overthe vocal ligament loosely attached to ligaments Thus there is a submucosal space along most of the length of truer Vocal cord. Superficial layer of lamina propria is referred to as the REINKE’S SPACE,
- 42. RECURRENT LARYNGEAL NERVE: RightRecurrent Laryngeal Nerve: arises from the vagus nerve at the level of subclavian artery,hooks around it and then ascends between the trachea and oesophagus. Left recurrent laryngeal nerve: arises from the vagus in the mediastinum at the level of arch of aorta,loops round it and then ascends into the neck in the trachea- oesophageal groove. Hence,the left recurrent laryngeal nerve has a much longer course which makes it more prone to paralysis as compared to the right one.
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- 44. SUPERIOR LARYNGEAL NERVE: Itarises from the inferior ganglion of the vagus nerve, descends behind the internal carotid artery and at the level of greater cornu of the hyoid bone, divides into internal and external branches. The external branch supplies the cricothyroid muscle, while the internal branch pierces the thyrohyoid membrane and supplies the sensory innervation to the larynx and hypopharynx.
- 45. CLASSIFICATION OF LARYNGEALPARALYSIS: Laryngeal paralysis can be UNILATERAL OR BILATERAL and may involve: 1)Recurrent laryngeal nerve 2)Superior laryngeal nerve 3)Both (Combined/Complete)
- 46. THEORIES ON POSITIONOF VOCAL CORD IN VOCAL CORD PARALYSIS: SEMON’S LAW: States that,in all progressive organic lesions, abductor fibres of the nerve which are phylogenetically newer are more susceptible and thus the first to be paralysed as compared to adductor fibres. WAGNER AND GROSSMAN HYPOTHESIS: Is the most widely accepted theory. It states that complete paralysis of the recurrent laryngeal nerve results in the vocal cord being in paramedian because of an intact cricothyroid muscle, which adducts the vocal cord. When the superior laryngeal nerve is also paralysed, the vocal cord will be in intermediate or cadaveric position because of loss of this adductive force.