Anatomy of Larynx

1. ANATOMY OF LARYNX Dr. Diptiman Baliarsingh 1st Year PG, Dept. of ENT, Hi-Tech Medical College & Hospital, Bhubaneswar

2. EMBRYOLOGY  During 4th wk, the tracheo-bronchial diverticulum appears in the ventral wall of primitive pharynx, just below hypobrachial eminence.  The edges of this groove form oesophago-tracheal septum, which fuses caudally leaving a slit like aperture cranially.  The cranial end of tube forms larynx & trachea  The caudal end of tube forms bronchi & lungs  The tube is lined by endoderm which forms the epithelial lining of entire respiratory system.

3.  Arytenoid swellings appear on both sides of tracheo-bronchial diverticulum. The Aryteniod swellings grow upwards and deepen to produce Ary-epiglottic folds  Hypobrachial eminence forms Epiglottis  Glottis forms just above the primitive aperture  Thyroid cartilage develops from the ventral ends of the cartilages of the 4th pharyngeal arch  Cricoid cartilage and cartilages of trachea develop from 6th arch  Superior & recurrent laryngeal branches of vagus nerve are derived from 4th & 6th arches which supply the larynx.

4. EMBRYOLOGICAL DEVELOPMENT OF LARYNX Structure Source Laryngeal mucosa Endoderm of cephalic part of foregut Laryngeal cartilages Mesenchyme Epiglottis Hypobranchial eminence Upper part of thyroid cartilage 4th branchial arch lower part of thyroid cartilage, cricoid, corniculate, and cunei-form cartilages 6th branchial arch Intrinsic muscles of larynx 6th branchial arch

5. GENERAL ANATOMY  Extent  From laryngeal inlet to inferior border of cricoid cartilage  3rd to 6th cervical vertebrae  Little higher in women  VC lie at C5 level in adults, C3/C4 in infants  Infantile larynx is smaller & funnel shaped  It is narrowest at the junction of sub-glottic larynx with trachea. * Slight swelling may result in marked airway obstruction  Laryngeal cartilages are much softer in infants and collapse more easily on forced inspiration

6.  As the larynx grows there is little difference in size between boys and girls till puberty, after which A-P diameter almost doubles in men, with a final A-P dia. of  36mm in Men  26mm in Women  Larynx is divided into 3 parts by False & True vocal cords  Supraglottis  Glottis  Subglottis

7.  Supraglottis consists of  Superiorly - epiglottis & aryepiglottic folds  Lower border - the ventricular bands (false cords)  Glottis consists of  Vocal cords  Anterior commissure  Posterior commissure  Subglottis consists of  Upto lower border of cricoid  It becomes trachea at lower border of cricoid

8. INFANT LARYNX  Position: Infant larynx is situated higher in the neck. Vocalcords lie at C3/C4 level and during swallowing go up to C1/ C2 level. In adults vocal cords lie at C5 level.  Cartilages: Laryngeal cartilages in infants are soft and collapse easily.  Epiglottis: It is omega shaped.  Arytenoids: They are relatively large and cover significant posterior part of glottis.  Thyroid: It is flat.  Cricoid: The diameter of cricoid is smaller than glottis.

9.  Cricothyroid and thyrohyoid spaces: They are very narrow. Hyoid bone overlaps thyroid and thyroid overlaps cricoid.  Size: The larynx of an infant is smaller and has a narrower lumen  Shape: It is conical and funnel-shaped  Submucosal tissue: It is thick and loose and becomes easily edematous in response to trauma or inflammation

10. LARYNGEAL FRAMEWORK - ANTERIOR VIEW

11. LATERAL VIEW OF LARYNX SHOWING CARTILAGES AND LIGAMENTS

12. POSTERIOR VIEW OF LARYNX SHOWING CARTILAGES AND LIGAMENTS

13. FRAMEWORK OF LARYNX  Consists of  Bone – Hyoid bone  Cartilages – 3 paired & 3 unpaired  3 unpaired – Thyroid cartilage Cricoid cartilage Epiglottis  3 paired – Arytenoid cartilage Corniculate cartilage Cuneiform cartilage  Ligaments – Extrinsc & Intrinsic  Membranes  Muscles – Extrinsic & Intrinsic

14. HYOID BONE  U-shaped bone  Provides upper attachment for extrinsic muscles of larynx  Suspends the larynx in theneck  3 parts  Body – present anteriorly  Greater cornua – projects backwards  Lesser cornua – 2 small conical eminences

15. LARYNGEAL FRAMEWORK - ANTERIOR VIEW

16. THYROID CARTILAGE  2 lamina fused anteriorly in midline giving rise to laryngeal prominence  Angle of fusion –  90 degree in Men  120 degree in women  The posterior border of each lamina is prolonged above & below to form superior & inferior cornua  Superior cornua - long & narrow - curves upwards, backwrds & medially *Lateral thyroid ligament is attached  Inferior cornua - shorter and thicker - curves downward & medially *small oval facet jt. on which articulates cricoid cart.

17.  External Surface of Thy. cart.  On each lamina is a oblique line, curves downwards & forwards from superior thyroid tubercle to inferior thyroid tubercle.  The line marks the attachment of  Thyrohyoid  Sternothyroid  Inferior constrictor muscles  Inner aspect of Thy. Cart.  Thyroepiglottic ligament is attached just below the thyroid notch in midline  Below this on each side of midline is attached  Vestibular & Vocal ligaments  Thyroaryteniod Muscle  Thyroepiglottic Muscle  Vocalis Muscle

18.  The fusion of the anterior ends of the two vocal ligaments produce Anterior commissure  The superior border of each lamina gives attachment to thyrohyoid ligament  The inferior border gives attachment to cricothyroid ligament

19. POSTERIOR VIEW OF LARYNX SHOWING CARTILAGES AND LIGAMENTS

20. LARYNGEAL FRAMEWORK

21. CRICOID CARTILAGE  It is the only complete cartilagenous ring in the airway  It forms the inferior part of the larynx  It has a deep broad lamina posteriorly & narrow arch anteriorly with a facet for articulation with the inferior cornu of the thyroid cartilage  The lamina has sloping shoulders on which the articular facets for the arytenoids are found  A vertical ridge in midline of lamina give attachment to longitudinal muscle of oesophaus  Shallow concavity on each side gives origin to posterior cricoaryteniod

22. CRICOID CARTILAGE

23. EPIGLOTTIS  Thin leaf like sheet of elastic fibrocartilage  Projects upwards behind the tongue and hyoid bone  It is attached  Inferiorly – to thyroid cartilage, just below thyroid notch in midline by thyroepiglottic ligamnet  Anteriorly – to hyoid bone by hyoepiglottic ligament  Space between these two ligaments forms pre-epiglottic space  From the sides of epiglottis, aryepiglottic folds pass down to the apex of aryteniods

24. SAGITTAL SECTION OF LARYNX

25.  The posterior surface of Epi. is indented by numerous small pits into which mucus glands project  The anterior surface is coverd by mucous membrane superiorly & forms the posterior wall of vallecula  The mucous membrane overlying epiglottis is reflected on base of tongue forming  Glossoepiglottic fold – midline  Lateral glossoepiglottic fold – laterally

26. EPIGLOTTIS

27. ARYTENOID CARTILAGES  Irregular, three sided pyramid  with a  Forward projection – Vocal Process – attached Vocal folds  Lateral projection – Muscular process – attached posterior cricoarytenoid & lateral cricothyroid muscles  Anterolateral surface – is divided into two fossa by a crest from apex into  Upper triangular fossa – attachment to Vestibular ligament  Lower triangular fossa – attch. to Vocalis & Lateral cricoaryteniod muscle

28. ARYTENOIDS

29.  The apex is curved backwards & medially, and is flattened for articulation with corniculate cartilage.  The medial surface is covered with mucous membrane  Posterior surface is covered by transverse aryteniod muscle  The base is concave and provides smooth surface for articulation with cricoid *this is a synovial joint with lax capsular ligaments allowing - 1. rotarory movements 2. medial & lateral gliding movements  Post. cricoarytenoid ligament prevents forward movement of arytenoid cartilage

30. ATTACHMENTS OF ARYTENOIDS

31. CORNICULATE & CUNEIFORM CARTILAGES  Corniculate Cartilages (of Santorini)  2 small conical nodules of elastic fibrocatilage  Articulate by a synovial joint with the apices of aryteniod cartilages  Situated in the posterior part of aryepiglottic fold  Cuneiform Cartilages (of Wrisberg)  2 small elongated flakes of fibroelastic cartilage (rod shaped cart.)  One in each margin of aryepiglottic folds

32. JOINTS  Cricoarytenoid joint:  This synovial joint is formed between the base of arytenoid and a facet on the upper border of cricoid lamina.  Two types of movements are possible at this joint; rotatory and gliding.  The rotatory movement occurs at a vertical axis and abducts or adducts the vocal cord.  Arytenoids glide laterally and medially and help in closing or opening the posterior part of glottis.  Cricothyroid joint:  This synovial joint is formed between the inferior cornua of thyroid cartilage and a facet on the cricoid cartilage.

33. LIGAMNETS & MEMBRANES  EXTRINSIC LIGAMENTS  They connect laryngeal cartilages to hyoid bone above & trachea below  Superiorly – Thyrohyoid membrane stretches between upper border of thyroid cartilage & posterior surface of the body & greater cornua of hyoid  The membrane is a fibroelastic tissue & is re-enforced by fibrous tissue in  midline as median thyrohyoid ligament &  posteriorly as lateral thyrohyoid ligament ( ligament often contains a small nodule of cartilage – Cartilago Triticea)  The membrane is pierced by Internal branch of Sup. Laryngeal Nerve & Sup. Laryngeal Vessels  Cricotracheal ligament unites lower border of cricoid with first tracheal ring

34.  INTRINSIC LIGAMENTS  They  Connect the laryngeal cartilages together  Strengthen the capsule of intercartilagenous joints  Form a broad sheet of fibroelastic tissue – fibroelastic membrane  Fibroelastic Membrane is divided into upper & lower part by laryngeal ventricle  Upper Quadilateral Membrane – extends between lateral border of epiglottis & arytenoid cartilages  Upper margin forms aryepiglottic fold  Lower margin forms vestibular ligament underlying the vestibular fold (false cords)

35. SAGITTAL SECTION OF LARYNX

36.  Lower part is thicker containing elastic fibres, called as cricovocal lig. / cricothyroid lig. / conus elasticus  It is attached  Above to thyroid cart. anteriorly & vocal process of arytenoid posteriorly  Below to upper border of cricod cartilage  The free upper border of this memb. forms the Vocal Ligament (true cord)  Anteriorly there is thickening of this membrane - forming cricothyroid ligament, which connects cricoid and thyroid cartilages in the midline.

37. LATERAL VIEW OF LARYNX SHOWING CARTILAGES AND LIGAMENTS

38. LATERAL VIEW OF LARYNX AFTER REMOVING RIGHT LAMINA OF THYROID CARTILAGES

39. CORONAL SECTION OF LARYNX

40. MUSCLES OF LARYNX  Extrinsic Muscles – attach larynx to surr. structures & maintain positing of larynx in neck  Infrahyoid group - Thyrohyoid, - Sternothyroid, - Sternohyoid.  Suprahyoid group - Mylohyoid, - Geniohyoid, - Stylohyoid, - Digastric, - Stylopgaryngeus, - Palatopharyngeus, - Salpingopharyngeus.

41. EXTRINSIC MUSCLES OF LARYNX

42.  Intrinsic Muscles – are all paired (excp. Tr. A) & move the cartilages in the larynx & regulate the mechanical properties of larynx  Open & Close glottis - Posterior Cricoarytenoid - Lateral Cricoarytenoid - Transverse Arytenoids(unpaired)* - Oblique Arytenoids(paired)  Control tension of VC - Thyroarytenoids (vocalis) - Cricothyroid  Alter the shape of laryngeal inlet - Aryepiglotticus - Thyroepiglotticus

43. VOCAL CORDS  Abductors:  Posterior cricoarytenoid  Adductors:  Lateral cricoarytenoid  Interarytenoid (transverse and oblique arytenoids)  Thyroarytenoid (external part)  Tensors:  Cricothyroid  Relaxers:  Vocalis  Thyroarytenoid (internal part)

44. INTRINSIC MUSCLES OF LARYNX AND THEIR ACTIONS

45. INTRINSIC MUSCLES OF LARYNX AS SEEN ON ITS POSTERIOR VIEW

46. INTRINSIC MUSCLES OF LARYNX AS SEEN ON ITS LATERAL VIEW

47. LATERAL VIEW OF LARYNX SHOWING CRICOTHYROID MUSCLE, CARTILAGES AND LIGAMENTS

48. EXTRINSIC MUSCLES OF LARYNX  INFRAHYOID GROUP 1. Thyrohyoid  Origin - Oblique line of thyroid lamina  Insertion - Inferior border of the greater cornu of the Hyoid  Function - Elevates the larynx on a fixed hyoid or depresses the hyoid on a fixed larynx  Innervation - Hypoglossal (C1 root)

49. 2. Sternothyroid  Origin - Posterior surface of manubrium and edge of the first costal cartilage  Insertion - Oblique line of the thyroid lamina  Function - Depresses the larynx  Innervation - Ansa cervicalis (C2, 3 roots) 3. Sternohyoid  Origin - Clavicle and posterior surface of the manubrium  Insertion - Lower edge of the body of the hyoid  Function - Depresses the larynx by lowering the hyoid  Innervation - Ansa cervicalis (C1, 2, 3 roots)

50.  SUPRAHYOID GROUP 1. Mylohyoid  Origin – Mylohyoid line in inner aspect of mandible  Insertion – Midline raphe & body of hyoid  Function – raises & pulls hyoid anteriorly  Innervation – Nr. to Mylohyoid 2. Geniohyoid  Origin – Genial tubercle on mandible  Insertion – upper border of the body of hyoid  Function – raises & pulls the hyoid forwards  Innervation – Hypoglossal (C1 root)

51. 3. Stylohyoid  Origin – back of the styloid process  Insertion – base of greater cornu of the hyoid  Function – retractor & elevator of hyoid for swallowing  Innervation – facial nerve 4. Digastric  Origin – Digastric notch on the medial surface of the mastoid process  Insertion – Lower border of the mandible (a fibrous sling holds the tendon to the lesser cornu of hyoid)  Function – Anterior belly – pulls the hyoid anteriorly & up Posterior belly – pulls the hyoid posteriorly & up  Innervation - Ant. belly – Nr to mylohyoid Post. belly – Facial Nr

52. 5. Stylopharyngeus  Origin – Medial aspect of styloid process  Insertion – Post. border of lamina of thyroid cart.  Function – Elevates the larynx  Innervation – Glossopharyngeal Nr 6. Palatopharyngeus  Origin – Palatine aponeurosis & post margin of hard palate  Insertion – Post. border of thyroid alar & cornua  Function – helps tilts the larynx forwards  Innervation – Accessory Nr (pharyngeal plexus) 7. Salpingopharyngeus  Origin – Eustachian Tube  Insertion – Post. border of thyroid cartilage  Function – Elevates the larynx  Innervation – Pharyngeal plexus

53. SUPERIOR VIEW OF THE INSIDE OF LARYNX AS SEEN DURING LARYNGOSCOPIC EXAMINATION

54. INTRINSIC MUSCLES OF LARYNX  OPEN & CLOSE THE GLOTTIS 1. Posterior Cricoarytenoid  Origin – Lower & medial surface of back of cricoid lamina  Insertion – it fans out to be inserted into the back of the muscular process of the arytenoid  Function – Opens the glottis (Upper horizontal fibres – rotate the arytenoids & move the muscular process towards each other separating the vocal process & abducting the cords Lower vertical fibres – draw the arytenoids down the sloping shoulders of the cricoid separating the lamina)  Effect - abducts & elevates the tip of vocal process - vocal fold becomes elongated & thin

55. INTRINSIC MUSCLES OF LARYNX

57. 2. Lateral Cricoarytenoid  Origin – sup. border of lat. part of the arch of cricoid  Insertion – muscular process of arytenoid  Function – adductus & lowers the tip of the vocal process by rotating the arytenoids medially  Effect – Vocal fold adducted, lowered, elongated & thinned 3. Transverse Arytenoids(unpaired)  Origin – post. surf of muscular process & outer edge of arytenoid  Insertion – crosses over & attaches on same point on other arytenoid 4. Oblique Arytenoids(paired)  Origin – post. surf of muscular process (superfi. to Tr .Ary)  Insertion – Apex of other arytenoid  Function – Adducts VC & controls the position of VC  Effect – No significant effect on Vocal fold

60.  CONTROL THE TENSION OF VOCAL FOLDS 1. Thyroarytenoids (Vocalis) – it is a broad sheet of muscle lies lateral to & above the free egde of cricovocal ligament (conus elasticus). Its lower part is thicker and forms vocalis muscle.  Origin – back of the thyroid prominence & cricothyroid ligament  Insertion – vocal process of arytenoid & anterolateral surface of the body of arytenoid  Effect – Lowers, shortens & thickens the vocal folds

61. STRUCTURE OF VOCAL FOLD. CROSS-SECTION

62. 2. Cricothyroid – it is the only intrinsic muscle that lies outside the cartilagenous framework of larynx & *also the only muscle amongst all the intrinsic muscles of larynx which is supplied by Ext. br. of SLN, rest all being supplied by RLN.  Origin – lateral surface of the anterior arch of cricoid, the fibers fan out and pass backwards in two groups  Lower Oblique & Anterior Straight fibres  Insertion - Lower Oblique fibres – pass backwards and laterally to the anterior border of the inferior cornu of thyroid cartilage. - Anterior Straight fibres – ascend to the posterior part of the lower border of thyroid lamina  Effect – Rotates the cricoid cartilage about the horizontal axis passing through the cricothyroid joint

65.  ALTER THE SHAPE OF LARYNGEAL INLET 1. Aryepiglotticus – continuation of oblique arytenoid  Origin – posterior aspect of muscular process of arytenoid  Insertion – fibres pass around the apex of the opposite arytenoid & insert into the aryepiglottic fold  Effect – weak sphincter of laryngeal inlet 2. Thyroepiglotticus – continuation of thyroarytenoid  Origin – back of thyroid prominence & cricothyroid ligament  Insertion – fibres pass upwards into aryepiglottic fold  Effect – widens the inlet of larynx by pulling the aryepiglottic flods slightly apart

66. THE GLOTTIS  The glottis lies between False VC & True VC which cover vestibular & vocal ligaments  In glottis, laterally lies Laryngeal Ventricle (sinus of larynx)  In the anterior part of ventricle, the saccule of larynx acsends between vestibular ligament & inner surf. of thyroid cartilage.  Laryngocele – abnormally enlarged & distended saccule containing air  Retension Cyst – due to obstruction of mucous glands saccule

67.  The glottis (RIMA GLOTTIDIS) is the narrowest part of adult laryngeal cavity & lies between VC & arytenoids on two sides  The size & shape of glottis varies with the activites of VCs  Vestibular Folds –  2 thick folds of mucous membrane enclosing vestibular ligament  VL is the lower border of upper quadilateral membrane  It is fixed – in Front – at angle of thyroid cartilage just below attch. of epiglottic cart. Behind – anterolateral surface of arytenoids

68.  Vocal Folds –  Extend from the middle of the angle of thyroid cartilage to the vocal process of arytenoid cartilage  Underneath, there is the upper border of Conus Elasticus  Each fold is layered structure consisting of 1. Superficial layer of non-keratinizing stratified squamous epithelium 2. Lamina propria – 3 distinct layers  Superficial layer ( Reinke’s space) – contains a fibrous substance  Intermediate layer – contains elastic fibres  Deep layer – contains collagen fibres  Intermediate & Deep layer form VOCAL LIGAMENT 3. The vocalis muscle, forms the main body of VF lies lateral & deep

69. STRUCTURE OF VOCAL FOLD - CROSS-SECTION

70.  The layered structure of vocal fold is not uniform in its entire length.  Anterior end of VF lies a mass of collagen fibres which are connected to inner perichondrium of thyroid cartilage & to deep layer of lamina propria posteriorly  Adjacent to this mass of collagen fibres, posteriorly, lies a mass of elastic fibres continuous with intermediate layer of LP, called Anterior Macula Flava. A similar structure at posterior end of membranous part of VF  These serve as cushions to protect the ends of vocal folds from mechanical damage caused by vocal fold vibration.  Anterior 3/5th of VC is between vocal folds – called Intermembranous part of cord  Remaining 2/5th posteriorly are between vocal process of arytenoid – called Intercartilagenous part of cord

71. MUCOUS MEMBRANES OF LARYNX  The m.m. lining is closely attached over the posterior surface of epiglottis, corniculate & cuniform cartilages and all over the vocal ligament.  Elsewhere it is loosely attached & prone to edema  Most of larynx* is lined by pseudo-stratified cilliated columnar ‘respiratory-type’ epithelium  * The upper half of posterior surface of epiglottis, the upper part of aryepiglottic fold, posterior glottis & vocal folds are covered with non-keratinizing stratified squamous epithelium.

72.  Mucous glands are freely distributed throughout the mucous membrane & at particularly numerous on the posterior half of epiglottis where they form indentation into the cartilage & in the margins of the lower part of the aryepiglottic folds and saccules.  The vocal folds do not posses any glands & the mucous membrane is lubricated by mucus from the glands of the saccules. * if these glands cease to function, i.e. after radiation the the sq. epithelium of vocal cords tend to dessicate.

73. LARYNGEAL SPACES  PRE-EPIGLOTTIC SPACE  Wedge shaped space  Boundaries  Anteriorly – thyrohyoid ligament & hyoid bone  Posteriorly – epiglottis (infrahyoid part)  Superiorly – hyoepiglottic ligament  Inferiorly – thyrpoepiglotic ligament * Tumour may spread through 1. perforations in epiglottis 2. directly through hyo-epiglottic ligament  Pre-epiglottic space is continous laterally with the para-epiglottic space

74.  PARA-GLOTTIC SPACE  Boundaries –  Antero-Laterally – thyroid cartilage & cricothyroid membrane  Medially – conus elasticus & quadrangular membrane  Posteriorly – pyriform fossa  It encompasses laryngeal ventricles & saccules  REINKE’S SPACE  Lies under epithelium of VC’s  Boundaries  Abv & Blw – Arcuate lines  Ant – Ant. Commissures  Post – Vocal process of arytenoids

75. NERVE SUPPLY OF LARYNX  The motor and sensory supply of larynx is from VAGUS – by superior & recurrent laryngeal nr.s  SUPERIOR LARYNGEAL NERVE  Arises from inferior ganglion of vagus & also receives a branch from superior cervical sympathetic ganglion.  It decends lateral to pharynx behind ICA & at the level of greater horn of hyoid it divides into small external branch & larger internal branch  EXTERNAL BRANCH – motor supply to cricothyroid muscle

76.  INTERNAL BRANCH – pierces thyrohyoid memb. & divides into two main sensory & secretomotor br., & also carries afferent fibres from neuromuscular spindles & other stretch receptors of larynx Upper branch – supplies mucous memb. of lower part of pharynx, epiglottis, vallecula & vestibule of larynx Lower branch – supplies aryepiglottic fold & mucous membrane of larynx till level of vocal cords  In its course beneath m.m. of medial wall of pyriform fossa, it is accessible for inj. of LA for providing anaesthesia for most of pyriform fossa.  SLN ends by piercing inf. constricter muscle of pharynx & unites with the ascending br of recurrent laryngeal nerve. – called as Galen’s anastomosis

77.  RECURRENT LARYNGEAL NERVE  RIGHT RLN – leaves vagus as it crosses Right sub-clavian artery & loops under the artery ascending in the TE groove to reach larynx  LEFT RLN – the nerve originates from vagus as it crosses aortic arch, it passes under the arch & ligamentum arteriosum to reach TE groove  In the NECK – both follow same course and pass upwards accompanied by laryngeal branch of inferior thyroid artery  They pass deep to the lower border of inf. constricter muscle & enter the larynx behind cricothyroid joint.  Then divides into motor & sensory branches  MOTOR BR – all intrinsic muscles of larynx, except cricothyroid  SENSORY BR – supplies laryngeal mucosa below the level of vocal cords + aff. fibers from stretch receptors of larynx

78. NERVES SUPPLYING THE LARYNX AND THEIR RELATIONS ESPECIALLY WITH ARTERIES

79.  The relationship between RLN & inferior thyroid art. is variable  It may cross in front of, or behind the artery or may pass between the terminal branches of artery  On the Rt side there is equal chance of the nerve lying in any of three locations but on the Lt side it usually lies posteriorly to artery.

80. LARYNGEAL VASCULATURE  ARTERIAL SUPPLY  Laryngeeal branches of superior & inferior thyroid arteries  Cricothyroid br of superior thyroid artery  The superior laryngeal artery arises from superior thyroid artery – passes deep to thyrohyiod muscle. Together with the int. br of SLN it pierces thyrohyiod memb. to supply larynx  The inferior laryngeal artery arises from inferior thyroid artery at lower border of thyroid gl. And ascends on the traches with RLN. It enters the larynx beneath the lower border of inf constricter to supply it.  The cricothyroid artery passes upper part of cricothyroid ligament to supply larynx.

81.  VENOUS DRAINAGE  Accompany arteries  Superior laryngeal vein  superior thyroid vein / facial vein  IJV  Inferior laryngeal veins  inferior thyroid veins  bracheocephalic vein * some veins  middle thyroid vein  IJV  LYMPHATICS  Divided into two groups by vocal folds into upper & lower drainage  LARYNX ABOVE VOCAL FOLDS – drain by vessels accompanying SL vein  Upper deep cervical LNs  LARYNX BELOW VOCAL FOLDS  prelaryngeal & pretracheal nodes  Lower deep cervical nodes  The vocal folds have no lymphatics as they are firmly bound down to underlying vocal ligament

82. NERVES SUPPLYING THE LARYNX AND THEIR RELATIONS ESPECIALLY WITH ARTERIES

83. FUNCTIONS OF LARYNX  4 main funtions of larynx - 1. Protection of lower airways  Sphincteric closure of laryngeal inlet  Cessation of respiration  Cough reflex 2. Phonation & speech 3. Respiration 4. Fixation of chest

84. LASTLY... Its that part of our body which helps us to communicate verbally with the whole world...! From the first cry of the baby to the sweet tunes of a melodius song...!! Its all about LARYNX...!!!

85. THANK YOU...  REFERENCES  GRAY’s Anatomy - 39th Ed.  Scott Brown’s Otorhinolaryngology & Head and Neck Surgery – 7th Ed.  Cumming’s Otolaryngology & Head and Neck Surgery - 5th Ed.  Mohan Bansal – 2nd Ed.  BD Chaurasia’s – Human Anatomy 3rd Ed.