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10. LARYNX AND TRACHEA.pptxxxxxxxxxxxxxxxxxx
- 1. LARYNX AND TRACHEA DR.JADA DR. MBIINE
- 2. OUTLINE • INTRODUCTION • EMBRYOLOGY •SURFACE ANATOMY • GROSS ANATOMY – CARTILAGES – LIGAMENTS – MUSCLES – CORDS – CAVITIES
- 3. • GROSS ANATOMYCONTINUED: – BLOOD SUPPLY – LYMPHATIC DRAINAGE – INNERVATION • GROSS ANATOMY OF THE TRACHEA • RELEVANT HISTOLOGY • CLINICAL CORRELATES
- 4. INTRODUCTION • The larynxis a component of the airway connecting the phaynx to the Trachea. • Its is a very essential structure because: • It is a conduit of air during breating • It has sphincteric action to protect the airway from foreign bodies • Its is the source of sound during phonation.
- 5. • The larynxis a 5-7 cm long structure. • Its upper boundary starts at the tip of the epiglottis, opposite the 3rd to 4th, cervical vertebra. • Its lower end is at the lower border of the cricoid cartilage. • This lies opposite the 6th cervical vertebra. www.phon.ox.ac.uk
- 6. EMBRYOLOGY • The internallining of the larynx originates from the endoderm • The cartilages, muscles and ligaments originate from the messenchyme of the 4th and 6th Pharyngeal arches. • Initially the Laryngeal orifice is a sagittal slit, however it later takes on a T shape as a result of the rapid proliferation of the mesenchyme around it.
- 7. • Once themesenchyme transforms into the thyroid, cricoid and arytenoid cartilages, the characteristic adult shape of the laryngeal orifice is thus recognised. • Concurrently as the cartilages differentiate, the mucosal epithelium rapidly proliferates occluding the laryngeal orifice. • However this later recanalises with resultant creation of the ventricles, being bound by folds which later differential into the vestibular and vocal folds.
- 8. • Since musculatureof the larynx is derived from mesenchyme of the fourth and sixth pharyngeal arches, all laryngeal muscles are innervated by branches of the tenth cranial nerve, the vagus nerve. • The superior laryngeal nerve innervates derivatives of the fourth pharyngeal arch, and the recurrent laryngeal nerve innervates derivatives of the sixth pharyngeal arch. • The trachea develops from the lung bud that separates from the foregut.
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- 13. The cricoid cartilage,a key landmark in the neck, indicates the: • Level of the C6 vertebra. • Site where the carotid artery can be compressed against the transverse process of the C6 vertebra. • Junction of the larynx and trachea. • Joining of the pharynx and esophagus. • Point where the recurrent laryngeal nerve enters the larynx. • Site that is approximately 3 cm superior to the isthmus of the thyroid gland.
- 14. GROSS: CARTILAGES • MIDLINE(UNPAIRED) – Thyroid(H) – Cricoid(H) – Epiglottic(E) • PAIRED: – Arytenoids(H) – Corniculate (E) – Cuneiform(E)
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- 17. Cricoid cartilage • Importantfrom structural & functional point of view – Base for entire larynx – Support to arytenoid – Attachment to intrinsic muscles – Only part of cartilagenous framework that forms continuous 360 degree ring – Once injured or strictured , difficult to resect while preserving laryngeal function
- 18. Epiglottis • Thin leafshaped fibro-cartilage, situated in midline • Upper free end broad & rounded, projects up behind base of tongue • Narrow base called pitiole • This attachment forms lower limit of pre-epiglottis space
- 19. Arytenoids • Paired cartilages,pyramidal in shape • Base articulated with cricoid • PCA & LCA muscles attach on muscular process • Anterior angle elongated into vocal process which receives insertion of vocal ligament
- 21. joints • Cricothyroid joint: –Its synovial – Axis is transverse line between the two joints – Recurrent laryngeal nerve lies immediately behind this joint • Cricoarytenoid joint: – Synovial – Allows rotatory and lateral gliding movts.
- 22. LIGAMENTS • EXTRINSIC: – Thyrohyoidligament. • Has a bursa which maybe associated with remnants of the thryoglossal cysts. • Forms the lateral wall of the pirifom recess • Perforated by the superior laryngeal artery and internal laryngeal nerve. • Not part of the larynx but anchors it to the hyoid. – HYOEPIGLOTTIC LIGAMENT – THYROEPIGLOTTIC LIGAMENT – CRICOTRACHEAL LIGAMENT
- 23. INTRINSIC LIGAMENTS OFLARYNX • QUANDRANGULAR MEMBRANE: – Fibroelastic – Extends between the arytenoids and the epiglottic cartilages. – Its upper border forms the aryepiglottic ligament – Its lower border forms the Vestibular ligament • CRICOTHYROID LIGAMENT: – Anterior(median) cricothyroid ligament – Paired Lateral cricothyroid ligaments(cricovoval)
- 24. LATERAL CRICOTHYROID LIGAMENTS •Attached below the upper margin of the cricoid cartilage • They pass up deep to the lamina of the thyroid cartilage on each side. Anterioly attached to the back of the thryoid angle midway between the notch and lower border. • Posterioly attached to the vocal processes. • Its free edge forms the VOCAL LIGAMENTS
- 25. Mucosa covering thevestibular and vocal ligaments forms the vestibular and vocal folds respectively.
- 28. CAVITY • Aditus(laryngeal inlet) •Vestibule • Ventricle • Laryngeal saccule • Rima glottis: • Infraglottic part
- 29. • Rima glottis: •ant 60% is intermembranous • Posterior 40% is intercartilaginous – 8mm wide post, in quiet respiration, – Saggital length: 23mm male, 17mm in female.
- 30. HISTOLOGY • Mucosa • isrespiratory hence: • Pseudostratified columnar ciliated epithelium. • Mucosa of anterior side of epiglottis is Stratified squamous epithelium. • Over Vocal folds: epithelium is stratified squamous. • Taste buds are present in the posterior epiglottic surface and the aryepiglottic folds.
- 31. HISTOLOGY Cont… • LaminaPropria: – Loose in all parts except over the vocal folds where the mucous membrane is very firmly attached. • Hence in cases of Laryngeal oedema, the swelling occurs above the rima glottis, however still this is life threatening.
- 32. MUSCLES • EXTRINSIC – Infrahyoidmuscles – Stylopharyngeus – Suprahyoid muscles • Elevators of the larynx and Hyoid.
- 33. Intrinsic muscles • alterthe length and tension of the vocal folds and the size and shape of the rima glottidis • ADDUCTORS OF THE VOCAL CORDS – Lateral cricoarytenoids – Transverse and oblique arytenoids • ABDUCTORS OF THE VOCAL CORDS – Posterior cricoarytenoid
- 34. • SPHINCTERS: – Lateralcricoarytenoids – Transverse and oblique arytenoids – Aryepiglottic muscles • TENSORS: – Cricothyroid muscles • Bt tensing and elongating the cords, they vary and raise the pitch of the voice. • RELAXERS: – Thyroartenoid muscles. – Vocalis(medial part of thyroarytenoid muscle*)
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- 40. Lymphatics • The laryngeallymphatic vessels superior to the vocal folds accompany the superior laryngeal artery through the thyrohyoid membrane and drain into the superior deep cervical lymph nodes. • The lymphatic vessels inferior to the vocal folds drain into the pretracheal or paratracheal lymph nodes, which drain into the inferior deep cervical lymph nodes.
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- 42. INNERVATION • Superior Laryngealnerve: – Internal laryngeal nerve: sensory to the supraglottic area. – External laryngeal nerve: motor to cricothyroid. • Recurrent Laryngeal nerve: – Divides into the anterior and posterior branches. – Ant branch: lat cricoarytenoid,thyroarytenoid, vocalis, aryepiglottic and thyroepiglottic muscles – Post branch: Post cricoarytenoid, transverse and oblique arytenoids – Sensory innervation to the mucosa of the infraglottic cavity.
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- 44. TRACHEA • The trachea,extending from the larynx into the thorax, terminates inferiorly as it divides into right and left main bronchi. • It is a fibrocartilaginous tube, supported by incomplete cartilaginous tracheal rings, that occupies a median position in the neck
- 45. • The trachealrings keep the trachea patent; they are deficient posteriorly where the trachea is adjacent to the esophagus. • The posterior gap in the tracheal rings is spanned by the involuntary trachealis muscle, smooth muscle connecting the ends of the rings
- 46. • In adults,the trachea is approximately 2.5 cm in diameter, whereas in infants it has the diameter of a pencil. • The trachea extends from the inferior end of the larynx at the level of the C6 vertebra. • It ends at the level of the sternal angle or the T4–T5 IV disc, where it divides into the right and left main bronchi
- 47. CLINIC • INJURY TOTHE LARYNGEAL NERVES • CANCER OF THE LARYNX • OEDEMA OF THE LARYNX • CRICOTHYROIDOTOMY • TRACHEOSTOMY • SUPERIOR LARYNGEAL NERVEBLOCK • CRASH INDUCTION/CRICOID PRESSURE • FB LARYNX and TRACHEA
- 50. RECURRENT LARYNGEAL NERVEINJURY • The voice is poor initially because the paralyzed vocal fold cannot adduct to meet the normal vocal fold. • Within weeks, the contralateral fold crosses the midline when its muscles act to compensate • results in the vocal fold on the affected side assuming the position midway between abduction and adduction.
- 51. • When bilateralparalysis of the vocal folds occurs, the voice is almost absent because the vocal folds are motionless in a position that is slightly narrower than the usually neutral respiratory position. They cannot be adducted for phonation, nor can they be abducted for increased respiration, resulting in stridor
- 52. • In progressivelesions of the recurrent laryngeal nerve, abduction of the vocal ligaments is lost before adduction; conversely, during recovery, adduction returns before abduction
- 53. • Unilateral partialsection of the recurrent laryngeal nerve results in a greater degree of paralysis of the abductor muscles than of the adductor muscles. The affected vocal fold assumes the adducted midline position
- 54. SUPERIOR LARYNGEAL NERVE •Paralysis of the superior laryngeal nerve causes anesthesia of the superior laryngeal mucosa. As a result, the protective mechanism designed to keep foreign bodies out of the larynx is inactive, and foreign bodies can easily enter the larynx.
- 55. • Injury tothe external branch of the superior laryngeal nerve results in a voice that is monotonous in character because the paralyzed cricothyroid muscle supplied by it is unable to vary the length and tension of the vocal fold.
- 56. • To avoidinjury to the external branch of the superior laryngeal nerve (e.g., during thyroidectomy), the superior thyroid artery is ligated and sectioned more superior to the gland, where it is not as closely related to the nerve. • Test for quality of phonation before thyroid surgery. Why?
- 57. Cancer of theLarynx • The incidence of cancer of the larynx is high in individuals who smoke cigarettes or chew tobacco. • Most persons present with persistent hoarseness, often associated with otalgia (earache) and dysphagia. Enlarged pretracheal or paratracheal lymph nodes may indicate the presence of laryngeal cancer
- 58. CRUSH INDUCTION • Rapidsequence intubation(RSI) is a medical procedure involving a prompt induction of general anesthesia and subsequent intubation of the trachea. • RSI is typically used in an emergency setting or for patients in the operating room.
- 59. • The advantageof using rapid sequence intubation is to quickly induce unconsciousness and cause paralysis which allow for easier tracheal intubation. • ROLE OF CRICOID PRESSURE/ SELLICK MANOUVRE IN RSI.
- 60. CRICOTHYTODOTOMY • A verticalor transverse incision is made in the skin in the interval between the cartilages. • The incision is made through the following structures: the skin, the superficial fascia (beware of the anterior jugular veins, which lie close together on either side of the midline), the investing layer of deep cervical fascia, the pretracheal fascia (separate the sternohyoid muscles and incise the fascia), and the larynx. • The larynx is incised through a horizontal incision through the cricothyroid ligament and the tube inserted.
- 61. • Complications • Esophagealperforation esp in children in whom the cross diameter of the larynx is so small. • Hemorrhage: The small branches of the superior thyroid artery that occasionally cross the front of the cricothyroid membrane to anastomose with one another should be avoided.
- 62. TRACHEOSTOMY • An openingis made in the trachea between the first and second tracheal rings or through the second through fourth rings.
- 63. WHAT TO WATCHOUT FOR • The inferior thyroid veins arise from a venous plexus on the thyroid gland and descend anterior to the trachea. • A small thyroid ima artery is present in approximately 10% of people; it ascends from the brachiocephalic trunk or the arch of the aorta to the isthmus of the thyroid gland.
- 64. • The leftbrachiocephalic vein, jugular venous arch, and pleurae may be encountered, particularly in infants and children. • The thymus covers the inferior part of the trachea in infants and children. • The trachea is small, mobile, and soft in infants, making it easy to cut through its posterior wall and damage the esophagus.
- 65. • Most complicationsresult from not adequately palpating and recognizing the thyroid, cricoid, and tracheal cartilages and not confining the incision strictly to the midline.
- 66. • Hemorrhage: Theanterior jugular veins. • the isthmus of the thyroid gland is transected, secure the anastomosing branches of the superior and inferior thyroid arteries that cross the midline on the isthmus. • Nerve paralysis: • Pneumothorax: • Esophageal injury
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