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ANATOMY OF LARYNX-.pptx anatomy of larynx notes
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- 2. OBJECTIVES Introduction Embryology Situation and extent Size Skeletalframework Subdivision of larynx Laryngeal spaces Blood supply Lymphatic drainage Functions of larynx
- 3. Embryology • Development oflarynx occur during the 4th week of intra uterine life. • It begins as a • As a slit like diverticulum (laryngotracheal groove) in the ventral wall of the primitive pharynx • The groove gradually deepens and its edges fuse to form a septum , this septum separates the laryngotracheal tube from the pharynx and oesophagus. The process of this fusion starts caudally and extend cranially. • Laryngeal cartilages develop from the mesenchyme of the branchial arches. • Thyroid cartilage develops from the 4th arch mesenchyme as two lateral plates meet in the midline • Cricoid- 6th arch • Intrinsic muscles –from mesoderm of 4th and 6th arches • .
- 4. Introduction • The larynxis a hollow Musculo-ligamentous structure with a cartilaginous framework • Organ for production of voice or phonation • Regulates passage of air in respiration • Acts as a sphincter at the inlet of lower respiratory tract
- 5. Situation and extent •Lies in anterior midline of neck • Situated between base of tongue and trachea • It is continuous below with the trachea • Lies opposite to C3 to C6 vertebrae in adult males • Slightly higher in infant and females
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- 7. Laryngeal Framework The skeletalframework of Larynx 9 cartilages Connected by Joints Ligaments Membranes Extrinsic and intrinsic muscles Hyoid bone
- 8. Laryngeal cartilages 3 unpaired •Thyroid • Cricoid • Epiglottis 3 paired • Arytenoid • Corniculate • cuneiform
- 9. The Thyroid cartilage •Largest of the cartilages • Hyaline cartilage • Lies opposite to C4 to C5 vertebrae • Two broad lamina which are fused together anteriorly in midline, Widely separated posteriorly The fused laminae formed a projection anteriorly ,called laryngeal prominence{Adam’s apple} The angle between two laminae is more acute in men 90 than in women 120 Acute angle responsible for greater length of VCs resulting in deeper pitch of the voice in male
- 10. Thyroid cartilage • Eachlamina is quadrilateral and has 4 borders upper border –gives attachment to the thyrohyoid membrane lower border-gives attachment to conus elasticus and cricothyroid muscle anterior borders meet at thyroid angle ,superior to laryngeal prominence form superior thyroid notch Inner surface of the thyroid angle gives attachment to thyroepiglottic ligaments,vestibular ligaments,vocal ligaments Inner surface of cartilage also gives attachments to thyroarytenoid,thyroepiglottic and vocalis muscle
- 11. posterior border Free,has superior and inferior horn The medial surface of the inferior horn has a facet for articulation with cricoid cartilage to form cricothyroid joint. The superior horn is connected by a lateral thyroid ligament LATERAL SURFACE/EXTERNAL SURFACE The lateral surface of each thyroid lamina is marked by a ridge- the oblique line ,extends from superior thyroid tubercle to inferior thyroid tubercle It marks the upper lateral border of the thyroid gland .
- 12. • 3 musclesoriginates from the oblique line 1.sternothyroid 2.Thyrohyoid muscle 2.Inferior constrictor muscles of pharynx Inner surface Covered by the loosely attached mucosa . Forms the lateral wall of pyriform fossa
- 15. THE CRICOID CARTILAGE •Signet ring shaped cartilage • Encircle larynx completely bellow the thyroid at the level opposite to C6 vertebra. • The only complete cartilaginous ring in the airway • Thicker and stronger • Anteriorly narrow arch and posteriorly broad lamina • 2 articular facets near at the junction of the arch and lamina
- 17. the cricoid arch •Outer surface gives attachment to Cricothyroid muscle Cricopharyngeaus muscle • Inner surface is smooth and lined by mucosa • Superiorly attached with thyroid cartilage • Inferiorly 1st tracheal ring by cricotracheal ligaments
- 18. cricoid arch • Superiorborder gives attachments to Thick median cricothyroid ligament Laterally to conus elasticus Lateral cricoarytenoid muscle Lower border attached to cricoid to 1st trach Eal ring by cricotracheal ligament
- 19. THE CRICOID LAMINA •Each lamina is approximately quadrilateral in outline. • It has a posterior median vertical ridge that creates posterior concavities on either side • These concavities gives attachment to posterior cricoarytenoid muscles . • The ridge gives attachment to longitudinal muscle fibres of the esophagus .
- 20. The cricoid lamina •Two articular facets • One facet –slopping shoulders ,articulates with the base of an arytenoid cartilage. • Other facet- on the lateral surface of the lamina near its base,articulates with medial surface of the inferior horn of thyroid cartilage
- 21. THE ARYTENOID CARTILAGE •2 In number • three sided Pyramid shaped • antlateral,medial and posterior • Concave Base articulates with slopping shoulder of cricoid lamina. • Muscular process laterally gives attachment to intrinsic muscles ….posterior cricoarytenoid and lateral cricoarytenoid muscle • Vocal process anteriorly gives attachment to vocal cord • Apex articulates with a corniculate cartilage • The vocal cord extends forward to the inner surface of thyroid cartilage. • Medial surface of each cartilage faces the other,covered by mucous membrane
- 23. • the anterolateralsurface is irregular& has 2 depressions,separated by a crest running from the apex . • These are for attachment of vocalis&lateral cricoarytenoid muscle(lower)and vestibular ligament (upper).
- 24. CORNICULATE AND CUNEIFORMCARTILAGES • Two small conical cartilages. • Fibroelastic cartilage • Present as nodules within the posterior part of aryepigllotic folds. • The base articulates with arytenoid cartilage. • Cuneiform cartilages - two small elongated flakes shaped • Fibroelastic cartilage • Located in each margin of the aryepiglottic fold • These cartilage keep the aryepiglottic fold upright ,prevents entry of food into laryngeal inlet
- 25. THE EPIGLOTTIS • Thin,leaf-like fibroelastic cartilage • Neonates and infants have long &floppy • Located posterior to the tongue and hyoid bone ,infront of laryngeal inlet • It has upper and lower ends , anterior , posterior surfaces and lateral borders • The anterior surface and upper part of posterior surfaces are lined by non-keratinized stratified squamous epithelium,lower part of posterior surface is lined by ciliated columner epithelium • The lower end is pointed and attached to the inner surface of thyroid cartilage at the angle by thyroepigllotic ligament in the midline.
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- 28. POSTERIOR SURFACE The posteriorsurface form the anterior wall of the upper part of laryngeal cavity. The inferior half of the posterior surface of the epiglottis is raised slightly to form epiglottic tubercle The posterior surface bellow the apex is pitted by mucous glands
- 29. Anterior surface(upper part):- attachedto the base of the tongue in midline by the median and lateral glossoepiglottic folds that bound the valleculae. Anterior surface(lower part):- connected to the hyoid bone by hyo-epiglottic ligament.
- 30. Lateral borders Provides attachmentto aryepiglottic folds The fold intervenes between laryngeal inlet medially and piriform fossa laterally . OSSIFICATION OF LARYNGEAL CARTILAGES Thyroid ,cricoid and base of arytenoid ;hyaline cartilage,mostly ossify after 25 years of age Epiglottis ,corniculate,cuneiform and processes of arytenoid ;elastic cartilage usually do not calcify
- 31. Joints of larynx 1Thecricothyroid joint 2.The crico-arytenoid joint 3.The aryteno corniculate joint
- 32. Cricothyroid joint • Synovialjoint • It is between the inferior horn of the thyroid cartilage and the facet on the side of the cricoid arch. • Movements- rotation around a transeverse axis that passes transeversely through both cricothyroid joints. • Around this transeverse axis ,one cartilage can move backwards and forwards on the other • This movement approximate the lamina of thyroid cartilage and the arch of the cricoid cartilage • These movement explained by 2 views
- 33. Membranes & ligamentsof larynx • Extrinsic; larynx is joined to surrounding structures 1.Thyrohyoid 2.Cricotracheal 3.Hyoepglottic Intrinsic ;cartilages are interconnected 1.Quadrangular membrane & vestibular ligament 2.Cricovocal membrane &vocal ligament
- 35. 1.Thyrohyoid membrane • Anchorsthe skeleton of larynx to hyoid bone(body &greater horn) • Superiorly stretches between the upper border of the thyroid cartilage and posterior surface of the body and greater horn of hyoid bone • Composed of fibroelastic tissue • Forms the lateral wall of pyriform recess. • It is perforated by internal laryngeal nerve and the superior laryngeal vessels •
- 36. Thyrohyoid membrane • Medialportion is thickened –median thyrohyoid ligament • The round,cord like lateral thyrohyoid ligaments
- 37. Intrinsic membrane • fibroelasticmembrane • Lies within the cartilaginous framework of larynx,beneath the laryngeal mucosa • Form discontinuous sheet,separated on both sides by a horizontal cleft • Cleft lies btween the vestibular ligament and vocal ligament • Quadrangular membrane-lies within the wall of upper part of laryngeal inlet (vestibule) • Conus elasticus-lies within the walls of infraglottic larynx,connects thyroid ,cricoid,arytenoid cartilage
- 39. QUDRANGULAR MEMBRANE • thinfibroelastic membrane • Each membrane passes from the lateral margin of the epiglottis to the apex of the ipsilateral arytenoid cartilage. • Anterior border is attached to the side of the lower half of the epiglottis. • Its posterior border, much shorter, is attached to the anterolateral surface of the arytenoid • Upper border form aryepiglottic ligament • Lower border forms vestibular ligament within the vestibular fold –false vocal cord • 2 aryepiglottic folds form the margins of inlet of the larynx
- 41. Muscles of thelarynx Extrinsic muscle;connects the larynx to neigbouring structures Infrahyoid Group; NAME ORIGIN INSERTION FUNCTION INNERVATION thyrohyoid Oblique line of thyroid lamina Inferior border of greater cornu of hyoid Elavation ofthe larynx Depression of hyoid Hypoglossal(C1) sternothyr oid Posterior surface of manubrium and edge of the 1st costal cartilage Oblique line of the thyroid lamina Depresses the larynx Ansa cervicalis (C2,3 ) Sternohyoi d Clavicle and posterior surface of mamubrium Lower edge of body of hyoid Depresses the larynx by lowering the hyoid Ansa cervicalis (C1,2,3)
- 43. Suprahyoid group name OriginInsertion action innervation mylohyoid Mylohyoid line on the inner aspect of mandible Midline raphe of body of hyoid Raises and pulls the hyoid anteriorly Inferior alveolar branch V3GGWE Geniohyoid Genial tubercle on the mandible Upper border of body of hyoid Raises &pulls the hyoid forward Hypoglossal(C1 root) stylohyoid Back of the styloid process Base of the greater cornu of hyoid Retractor and elevator of the hyoid Facial nerve digastric Digastric notch on the medial surface of the mastoid process Lower border of the mandible Ant. Belly pulls the hyoid anteriorly &up posterior belly pulls the hyoid post. &up Ant belly nerve to mylohyoid Post belly facial nerve stylopharyngeus Medial aspect of the styloid process Posterior border of lamina of thyroid cartilage Elevates the larynx Glossopharyngeal nerve palatopharyngeus Palatine aponeurosis and posterior margin of hard palate Posterior border of thyroid alar and cornua Tilts the larynx forward Accessory nerve(pharyngeal plexus) salpingopharyngeus Eustachian tube Posterior border of the thyroid cartilage Elevates the larynx Pharyngeal plexus
- 44. Role of extrinsicmuscles • Movement of larynx vertically up and down • Affects the pitch and quality of the voice • Elevation-increase in pitch • Elevation-decreases the length and calibre of the laryngopharynx and thus shorten the vocal tract • Frequency of sound increases • Depression of larynx -vice versa affect
- 45. Intrinsic muscles • Musclesacting on vocal cords 1.Cricothyroid Action –lengthens vocal cords &tensors 2 Thyroarytenoid muscles (internal part/vocalis muscle) Action-shortens vocal cords &relaxers 3.Posterior cricoarytenoid –abductor of vocal cords Adductor muscles; i.Lateral cricoarytenoid ii.Thyroarytenoid(external part) iii.Interarytenoideus(transeverse and oblique)
- 46. • Muscles actingon epiglottis; • Aryepiglotticus&thyroepiglotticus CRICOTHYROID MUSCLE Fan shaped muscle Origin;anterolateral surface of cricoid arch Insertion;lower border &inferior cornua of thyroid Action;lengthens and tenses vocal cords Innervation; external branch of superior laryngeal nerve
- 47. • POSTERIOR CRICOARYTENOIDMUSCLE • Also known as safety muscle of larynx as the only laryngeal muscle that open the glottis. • Origin;posterior surface of cricoid lamina • Insertion ;muscular process of arytenoid cartilage • Function ;abduction of vocal cord • Innervation ; recurrent laryngeal nerve
- 48. LATERAL CRICOARYTENOID MUSCLE •Origin;anteriorly,from the upper border of the cricoid arch • Insertion;front of the muscular process of the ipsilateral arytenoid cartilage • Action;Closes the rima glottides • Innervation ;recurrent laryngeal nerve.
- 49. INTERARYTENOID MUSCLE • Transverseinterarytenoideus • Origin ;back of one arytenoid and its muscular process • Insertion ;back of another arytenoid and its muscular process • Function;adduction of vocal cords ) • Oblique interarytenoideus; • Origin ;sam,e as transeverse interarytenoid ,superficial • Insetion ;apex of opposite side arytenoid • Function;adduction of vocal cords
- 51. THYROARYTENOID • Broad andthin muscle • Attachment ;anteriorly inner side of angle of thyroid cartilage ,posteriorly Anterolateral aspect of arytenoid cartilage • Action; relaxation and shortening of vocal ligament
- 52. VOCALIS MUSCLE(medialL PARTOF THYROARYTENOID) • Origin;lower half of thyroid angle • Insertion;lateral aspect of vocal process of arytenoid • Funtion ;shortens vocal cords (relaxers) • Only posterior half of the vocalis is relaxer,ant half is tensor
- 53. EXTERNAL PART OFTHYROARYTENOID • Origin ;lower half of thyroid angle • Insertion;anterolateral surface of arytenoids • Function ;adduction of vocal cords
- 54. ARYEPIGLOTTICUS • Origin ;muscularprocess of arytenoid(continuation of oblique arytenoid) • Insertion;aryepiglottic fold and lateral border of epiglottis • Function ;this muscle adducts arytenoids,pulls the epiglottis down and acts as a sphincter on laryngeal inlet
- 55. THYROEPIGLOTTIC MUSCLE Origin;lower halfof thyroid angle • Insertion;margin of epiglottis • Function; opens laryngeal inlet
- 56. The laryngeal inlet •Laryngeal cavity is entered by inlet • An aperture between larynx and pharynx • Faces backward and upward • Bounded by Anteriory upper edge of the epiglottis Posteriorly mucosal fold between the two arytenoid (posterior commissure) On each side ,aryepiglottic fold
- 57. THE VESTIBULE OFLARYNX • Space between laryngeal inlet and vestibular folds • Bounded by Anteriorly ,posterior surface of the epiglottis Laterally ,aryepiglottic fold Posteriorly ,interarytenoid mucosa
- 58. RIMA GLOTTIDIS /THEGLOTTIS • The glottis is a fissure between the vocal cords anteriorly and the arytenoid cartilage posteriorly • The anterior 2/3th of the glottis(anterior commissure) is bounded on each side by the vocal fold itself- the membranous part • The posterior 2/3th part lies between the vocal process of the arytenoid cartilage-the cartilaginous part • The interarytenoid part covered by mucosa is called posterior commissure. • It is the narrowest part of the larynx • Its witdth and shape vary with the movement of vc &arytenoid cartilages during respiration and phonation • In quite resting state the glottis is triangular in shape.
- 61. PARAGLOTTIC SPACE(TUCKER SPACE)AND PREGLOTTIC SPACE(BOYER SPACE)
- 62. RADIOLOGICAL VIEW OFPREGLOTTIC SPACE
- 63. LARYNGEAL MUCOSA • Thelaryngeal mucosa is continuous with the pharynx above and trachea bellow • Mucosa is loosely attached in all parts of larynx except over the vocal folds where it is firmly attached • Epithelium is maily ,pseudostratified ciliated columner epithelium except over the VC,upper part of the epiglottis,aryepiglottic fold where it is non keratinized stratified squamous epithelium • Mucous glands are abundant on the epiglottis,AEF and saccule • Vocal fold has very less no of mucous gland. • Each vocal folds consists of five layers –epithelial layer,lamina propria(superficial,intermediate,deep),thyroarytenoid muscle • The superficial layer is loosely attached to the underlying vocal ligament –produces a potential space called RINKIE’S SPACE
- 64. NERVE SUPPLY OFTHE LARYNX VAGUS NERVE SENSORY Above the vocal cords ;Internal laryngeal nerve,branch of superior laryngeal of the vagus nerve. Bellow the vocal cords;recurrent laryngeal nerve ,branch of the vagus nerve MOTOR ; all intrinsic muscles are supplied by the recurrent laryngeal nerve except CRICOTHYROID MUSCLE,which is supplied by the external branch of the superior laryngeal nerve
- 65. RECURRENT LARYNGEAL NERVE •LEFT RLN originates in the thorax at the level of arch of aorta and loops around it • RIGHT RLN originates in the root of the neck and hooks around rt subclavian artery • Both nerves ascend in the neck in the groove bwtween trachea and esophagus • Than enters the larynx deep to the margin of the inferior constrictor. • Main trunk of RLN devides into 2 branches ; 1.Anterior or motor branch 2.Posterior or sensory branch The anterior branch ascends posterior to the cricothyroid joint and its ligament