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anatomy of larynx with tumor barriers
This document provides an overview of laryngeal anatomy including: - The development of the larynx from embryology to differences between pediatric and adult larynx. - Descriptions of the cartilages, muscles, membranes and nerves of the larynx. - Details on the sizes and dimensions of structures in the larynx between males and females. - Identification and descriptions of the supraglottic, glottic, and subglottic regions as well as the spaces within the larynx. - Explanations of the extrinsic and intrinsic muscles of the larynx and their actions.
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anatomy of larynx with tumor barriers
- 1.
- 2. Development oflarynx (embryology) Paediatric v/s adult larynx Descriptive anatomy Cartilages of larynx Muscles of larynx Membranes Nerve supply / blood supply /lyphatics Potential spaces Barriers of cancer spread
- 3. 3 LaryngoTracheal Groove Forms inthe ventral wall of Pharynx in 4th week Development of larynx
- 6. 6 Pharyngeal Arches -Derivatives
- 8. 8 Pediatric Adult Size Luminal shapeConical / Funnel Shaped Cylindrical shaped Position C1/C2 C3-C6 Epiglottis Omega Leaf Shaped Thyroid Flat Shield Like Arytenoid Large Small Mucosa and Submucosa narrowest part Lax subglottis Adherent glottis
- 9. Located between 3rdto 6th vertebra in adults Measures 44 x 43 x 36 mm in men 36 x 41 x 26mm in women
- 10. 10 MALE FEMALE -Av Length44 mm 36mm -Transverse Diameter 43 mm 41mm -AP Diameter 36 mm 26mm Vocal cord Length -Child 8 mm 6mm -Adult 17-23 mm 15-19mm
- 11. 3 unpairedcartilage Epiglottis Thyroid Cricoid 3 paired cartilage Arytenoid Corniculate(santorini) Cuneiform(wrisberg) Laryngeal muscles Laryngeal membrane
- 12. 3 regions: Supraglottic Glottic Subglottic
- 13. Sites Extent Subsites SupraglottisTip of epiglottis to laryngeal ventricle Epiglottis ,False cords Aryepiglottic folds Arytenoid cartilages Preepiglottic space Vestibule Glottis From laryngeal ventricle to an imaginary plane 1cm below this level True vocal cords Anterior commissure Posterior commissure Subglottis From undersurface of true cord to inferior surface of cricoid cartilage
- 25. Anterior 3/5thof vocal cord is called intermembranous part- phonatory part Posterior 2/5th ofVC is called inter cartilaginous part-resp. part Height of theVF diminishes towards ant.commisure-as the inf. Edge ofVF slopes upwards No lymphatics in this plane of VF
- 27. Extrinsic Muscles– connect larynx to neighboring structures Elevators Depressors Intrinsic Muscles – Attach laryngeal cartilages to each other Acting on Vocal cords Acting on Laryngeal inlet 27
- 28. SUPRAHYOID (ELEVATORS) Primary elevators:stylopharyngeous Salpingopharyngeous Palatopharyngeous Secondary elevators Digastric muscle Stylohyoid Mylohyoid Geniohyoid Hyoglossus INFRAHYOID (DEPRESSOR) Sternohyoid Omohyoid Sternothyroid Thyrohyoid
- 31. Adjust tensionin the vocal ligaments Open and close the rima glottidis Open and Close the rima vestibuli Control the inner dimensions of the vestibule Facilitate closing of the laryngeal inlet.
- 32. Abductors • Posterior cricoarytenoid Adductors • Lateral cricoarytenoid •Transverse arytenoid • Thyroarytenoid (external part) • Cricothyroid Tensors • Cricothyroid • Vocalis
- 33. Openers of inletClosers of inlet Thyroepiglottic Interarytenoids
- 34. Muscle Origin InsertionAction Lateral cricoarytenoid Lat part of cricoid arch Muscular process Adductor Posterior cricoarytenoid Medial surface of cricoid lamina Muscular process Abductor Vocalis Back of thyroid prominence Muscular process Tensor Interarytenoid Muscular process Muscular process(opp side) Closure of inlet Cricothyroid Ant arch of cricoid Lower fibres – lesser cornu of thyroid cartilage Ant fibres – thyroid lamina tensor
- 37.
- 39. LAT.CRICOARYTENOID: It rotatesthe arytenoids medially and thus adducts the vocal cords. The vocal folds become thin and elongated. The edge becomes sharp and stiff. Transverse and oblique arytenoids also adduct the vocal folds.
- 40. CRICOTHYROID: Itrotates the cricoid cartilage lengthensthevocal cords by increasing the distance betweenthe thyroid angleand the arytenoids. The vocal fold thus becomes long and thin and theedges become sharp and stiffened
- 43.
- 44. The upper branchsupplies the mucous membrane of the lower part of the pharynx, epiglottis, vallecula, vestibule of the larynx and the lower branch descends in the medial wall of the piriform fossa beneath the mucous membrane and supplies the aryepiglottic fold and the mucous membrane of the larynx .
- 46. Enters larynxbehind cricothyroid joint, divides into motor and sensory branches Motor branch – all intrinsic muscles except cricothyroid Sensory – mucosa below level of vocal cords, afferents from stretch receptors Right Left Arises from vagus where it crosses subclavian loops under it, ascends in theTE groove Arises at aortic arch, passes under it, ascends in theTE groove
- 47. – internalbranch of SLN ends by piercing inferior constrictor where it unites with a branch of RLN. It’s a purely sensory loop
- 48. Superior laryngeal artery– branch of sup.thyroid artery. Inferior laryngeal artery – branch of inf.thyroid artery.
- 49. Follow A Sup laryngeal V enter IJV via sup thyroid & facial V. Inf laryngeal V drain into inf thyroid V-brachiocephalic V. Some drain into middle thyroid - IJV
- 50. Supraglottis – levelII, III (upper deep cervical LN) Subglottis – Level IV,VI
- 51. Supraglottis /sub glottis-respiratory pseudostratified columnar epithelium. Glottic -stratified non keratinized squamous epithelium.
- 52. Extend from thyroid cartilageto arytenoids Superficial layer – Reinke’s layer, loose fibrous tissue Intermediate layer, elastic fibres Deep layer, collagenous fibres, fibroblasts Mucosa Stratified squamous Lamina propria Muscle
- 55. Laryngeal development, Anatomicbarriers, Enzymatic activity. focal areas of vulnerability -ossified cartilage and natural interruptions in the perichondrium.
- 56. supraglottis -midlinebuccopharyngeal anlage with rich bilateral lymphatics. subglottis -propensity for extralaryngeal extension Glottis - midline fusion of lateral tracheobronchial primordium
- 61. Reinke’s space Sub mucosal space between mucosa and vocalis muscle . Very early glottic cancer remain superficial ,rarely penetrating the deeper tissue. Paraglottic space: Between mucosa of larynx and thyroid cartilage . It contains thyro-arytenoid muscle . Pre epiglottic space: Fat filled space lying between the hyoid bone and thyrohyoid membrane anteriorly and infrahyoid epiglottis posteriorly.
- 63. Submucosal spacebetween the mucosa of glottis and underlying vocalis muscle This act as bursa allowing the mucosa to slide over the underlying tissues producing fluency in normal speech Very early glottic ca remain superficial rarely penetrating deeper tissue Mucosa ofVC can therefore be stripped off without causing damage to underlying soft tissues with no alteration in voice
- 64. Bounded laterally -thyroid cartilage and thyrohyoid membrane superomedially - quadrangular membrane inferomedially - conus elasticus posteriorly - medial wall of piriform fossa. This space contains thyroarytenoid muscle- infiltration of this space causes fixity ofVC
- 65. hyaline cartilage-thyroid,cricoid, and arytenoid Thyroid cartilage- (male) age 20 ( female) a few years later Neoplastic invasion of the laryngeal cartilages generally takes place in the ossifi ed portion of the cartilage.
- 66.
Editor's Notes
- #4 PRENATAL DEVELOPMENT Organogenesis Larynx develops from endodermal lining and mesenchyme of 4th and 6th arches 20 days: Laryngotracheal groove 24days: lung buds appear 26days: LT tube descends, tracheo-esophageal septum develops 32days: Arytenoid swelling develop(arytenoids,corniculate and AE folds) FUSES CAUDALLY TO CRANIALLY. CRANIAL END EDGES REMAIN SEPARATE(SLIT LIKE APERTURE) CRANIAL END – LARYNX AND TRACHEA CAUDAL END – RT AND LT LUNG BUDS
- #5 Hypobranchial eminence gives rise to epiglottis and cuneiform cartilages Thyroid cartilage: 4th arch Cricoid cartilage: 6th arch 33 days: SLN from 4th arch 37 days: RLN from 6th arch 40 days: intrinsic muscles become evident Organ maturation 3rd month: Vocal processes of arytenoids develop. Thyroid laminae fuse 5-7th months: Submucosal glands appear, epiglottis matures POSTNATAL CHANGES Changes in axis, luminal shape and length
- #16 Laryngeal apperture Superior laryngeal inlet bounded by : Epiglottis :anteriorly Aryepiglottic folds :laterally Interartenoid space :posteriorly
- #17 Superior cornu – lateral thyroid ligament attached Inferior cornu – Articulates with cricoid Oblique lamina – attachement to thyrohyoid, sternothyroid and inf.constrictor Inner surface – Gives attachment to Thyroepiglottic ligament Vestibular and vocal ligaments Paired pyramid shaped hyaline cartilages Forward projection – vocal Lateral projection – muscular Apex – articulates with corniculate Medial surface – mucous membrane Posterior surface – transverse arytenoid Thyroarytenoids Vocalis Anterior commissure tendon
- #18 LARYNGEAL JOINTS Cricoarytenoid Joint: Its Synovial Joint surrounded by capsular ligament, formed between the base of arytenoid and upper border of cricoid lamina.Two types of movements, Rotatory, b) Gliding Movement Cricothyroid Joint: Its also a synovial joint formed by the inferior cornua of thyroid cartilage with facet on the cricoid cartilage.
- #21 Extends b/n epiglottis &arytenoid. Its upper margin-aryepiglottic fold & lower-vestibular fold(false cord).
- #24 The larynx openly communicates with the pharynx at the superior and posterosuperior laryngeal apperture Caudal to laryngeal apperture is the laryngeal vestibule Laryngeal vestibule:space between laryngeal apperture and the vestibular folds (false vocal folds) Borders:anterior:epiglottis Lateral :aryepiglottic folds
- #26 Rima glottidis : Narrowest part of laryngeal cavity two parts Intermembranous space b/w true vocal folds Intercartilagenous space b/w vocal processus of the arytenoid cartilage The anterior to posterior (length) ratio of the intermembranous portion to the intercartilaginous is 3:2; however, the ratio of cross-sectional areas defi ned by them is 2:3.
- #27 Laryngeal ventricle: k/a morgagni sinus Space b/w vestibular folds superiorly and true vocal folds inferiorly Anterior roof of the ventricle lies in a pouch like structure called as saccule,which functions to lubricate the ipsilateral vocal fold The lateral most aspect of the ventricle is the embryologic fusion point of buccopharyngeal and the tracheobronchial primordium which marks the border b/w the supraglottis and glottis
- #39 Posterior crico arytenoid (sanden and colleague 3 component : Verticle (abduct) Oblique(abduct) Horizontal(arytenoid stabilization during phonation)
- #43 The superior laryngeal nerve arises from the inferior ganglion of the vagus and receives a branch from the superior cervical sympathetic ganglion. It descends lateral to the pharynx behind the internal carotid artery and at the level of the greater horn of the hyoid divides into a small external branch and a larger internal branch.
- #44 The external branch provides motor supply to the cricothyroid muscle, while the internal branch pierces the thyrohyoid membrane above the entrance of the superior laryngeal artery and divides into two main sensory and secretomotor branches
- #49 Along with int.branch of SLN it pierces thyrohyoid membrane to supply mucosa and muscles Along with RLN it enters larynx beneath lower border of inf.constrictor
- #51 Supraglottis -arches 3and 4 glottis and subglottis -arch 6 therefore they have independent lymphatic drainage. Vocal cords have sparse lymphatics and hence lymph node metastasis from carcinomas are uncommon in early stages subglottis lymphatic pass through cricothyroid membrane and drain into prelaryngeal(Delphian), pretracheal or paratracheal node and deep cervical LN along inferior thyroid artery
- #52 and has abundance of mucous glands and lymphatic vessels in supraglottic region
- #54 Superficial Lamina Propria (SLP, Reinke’s Space): loose fibrous matrix (few fibroblasts), gelatinous consistency permits fluency of vocal fold vibration (mucosal wave) Thyroarytenoid Muscle Complex: thyromuscular bundle (thyroarytenoid muscle) and thyrovocalis bundle (vocalis muscle) NOTE: The gelatinous consistency of the SLP allows for fluency of vibration of the cover over the body during voicing (cover-body concept of vocal fold vibration). This vibratory activity can be readily visualized using videostroboscopy and is referred to as the mucosal wave
- #56 Laryngeal barriers to tumor spread are a product of laryngeal development, -Supraglottic and glottic/subglottic development is distinct and partially explains the metastatic behavior of laryngeal carcinoma anatomic barriers-, Dense connective tissues and elastic fibers provide anatomic barriers within the larynx enzymatic activity.- Laryngeal cartilage contains dense cartilage, enzyme inhibitors, and an intact perichondrium making it relatively resistant to tumor invasion
- #57 Clinically, this translates to a significant incidence of unilateral or bilateral cervical metastasis 25% to 75% for all T-stages Consequently, this embryologic boundary limits submucosal spread to adjacent sites within the larynx for early stage cancers, and the paucity of lymphatic in the glottis contains lymphatic spread to the neck allowing glottic cancers to remain localized to the larynx for longer periods of time
- #59 at the anterior commissure is naturally interrupted by the muscular attachment to the thyroid cartilage at the vocal ligament tendon creating a focal area of vulnerability to tumour spread. The elastic fibers in arteries make them relatively resistant Cartilaginous barrier Tumour required a rich source of O2 and nutrition to proliferate but cartilage lacks intrinsic blood supply. It works as a physical barrier. ----In addition cartilage contains enzyme inhibitor that block collagenase, protease and tumour angiogenenesis factor. ----Besides the intrinsic properties to resist tumour invasion, the perichondrium is also a strong barrier. ----But collagen bundle passed through the perichondrium at the muscular attachment point creating a natural interruption in the perichondrium.
- #60 Venous -so bulky tumour often cause narrowing of the lumen leading to the intimal damage Muscle-once the tumour has crossed the basement membrane it can readily spread the muscle fibers displacing the sarcolemma and initiating a local inflammatory response. Broyles ligament is met by the insertional fibers of the vocalis muscle, at this muscular attachment point the thyroid cartilage is devoid of a true inner perichondrium.
- #62 distinct compartment bounded by ligaments and perichondria . Cancer of larynx remain localized to it’s site of origin. partial laryngectomy are based on this fact. These barriers are effective only in early cancers . Once breached tumor spread occurs along the path of least resistance , where these are traversed by blood vessels and nerve .
- #63 Fat Anteriorly -hyoid bone and thyrohyoid membrane Posteriorly- infrahyoid epiglottis Apex- thyroepiglottic ligament, strong fibrous band This space is continuous on either side with paraglottic space deep to quadrangular memmbrane Tumor invasion of this space is staged as T3 This space is rich in lymphatics and relatively radioresistant because of sparse blood supply The cartilage of the epiglottis has numerous perforations that allow transit of tumor from the posterior surface of the epiglottis into the preepiglottic space Dehiscences in the thyrohyoid membrane created by the superior laryngeal neurovascular bundle allow extension of tumor from the pre-epiglottic space into the neck.
- #65 The paraglottis space is a potential space, and together with the pre-epiglottic space forms, a horseshoe-shaped fatty space around the internal laryngeal structures. Pressman’s confirmed this space by injecting dye lateral aspect of ventricle passed above and below the glottis deep to mucosa
- #66 hyoid bone is completely ossified at 2 years of age and is generally not a point of radiographic confusion. The incomplete ossification pattern may make it difficult to appreciate small areas of invasion