ANATOMYLARYNX

Larynx (voice box) is divided into three areas: Supraglottic area epiglottis to vestibule glottic area - in between vocal folds subglottic area- 1 cm below true vocal fold

*Larynx has a skeletal framework, mucosa and muscles. *True vocal fold - is the only squamous epithelium*Rest of larynx - respiratory epithelium (ciliated pseudostratified columnar epithelium)

CARTILAGESThyroid and Cricoid cartilage Cricothyroid joint Cricothyroid ligament area for esophageal tracheostomy. Arytenoids Corniculate Cuneiform cartilage Hyoid Bone

Epiglottis connected to thyroid cartilage via thyroepiglottic ligament

Two joints of larynx Cricothyroid joint Cricoarytenoid joint - basis for the key movement of the vocal fold (Abduction and adduction of vocal fold).

Cricothyroid membrane: location where emergency tracheostomy is performed (clinically); avascular.

2nd -4th tracheal ring: location for elective tracheostomy.

MUSCLESTwo groups of muscles in larynxI. Intrinsic - closes and opens the larynx, regulates pitch of voice Occur IN PAIRS of interest in this topic1) Posterior Cricoarytenoid MuscleAsk the patient to sniff. It is maximally stimulated when inhaling deeply and opens up the glottis.2) Lateral Cricoarytenoid Muscle main adductor of larynx. Important when you cough. Because before you cough, you inhale, the vocal fold closes, and then when pressure in subglottic area overcomes the force of this muscle, this opens up.3) Interarytenoid (oblique and transverse arytenoids muscles)4) Thyroarytenoid Muscle5) Cricothyroid Muscle- Lengthens the vocal folds, Increases the pitch. In transsexuals, mimic the action of muscle. Suture the cricoid and thyroid, and mimics the action of this muscle increase the pitch by a bit. But the true vocal fold is elastic so after sometime it would reverse to original voice(Refer to Table 17.1) IMPORTANT POINTS posterior cricoarytenoid muscles - only abductor muscle (opens the glottis). The rest are adductors (closes the glottis). Main intrinsic muscle of the larynx during inhalation. cricothyroid muscle - only pair of muscles innervated by Superior Laryngeal nerve. The rest innervated by recurrent laryngeal nerve. When it contracts it pulls the thyroid cartilage anteriorly thereby lengthening the vocal fold hence increase in pitch. interarytenoid muscle - only muscle innervated bilaterally by recurrent laryngeal nerve. Other muscles are innervated unilaterally thyroarytenoid muscle (vocalis muscle) main muscle for speech; when it contracts. It makes the vocal cord thicker therefore making the pitch lower

II. Extrinsic- elevates and depresses the larynx

NERVE SUPPLY Superior Laryngeal nerve External branch innervates cricothyroid muscle Internal branch - sensory to the larynx.Recurrent Laryngeal nerve- innervates the rest of intrinsic muscles of the larynx.

Cricothyroid cartilage emergency site of tracheostomy

Cricoarytenoid joint1) upward, lateral and posterior movement2) Moves the vocal folds

Glottal tongue sound from larynx without articulation; aah

BLOOD SUPPLY

Supraglottic and Glottic levels Superior Laryngeal ArterySubglottic level Inferior Laryngeal ArteryVenous Drainage: Inferior Thyroid Vein

SOUND PRODUCTION***Phonation + articulation= speechPhonation - Function of larynx- Production of raw soundArticulation- function of (vocal tract) lips. tongue, uvula, palate. pharyngealmuscle- Molding of sound into words

How does the larynx produce sound?- Sound is produced by vibration of vocal cords.- Must have two opposing forces opening and closing of glottis- thru actions of muscles and nerve of larynx

5 Steps1) Vocal cords will approximate2) Subglottic pressure increases leading to...3) Opening of the glottis (it opens inferior to superior)4) Vocal cords close again as the pressure of subglottic are drops due to the steady stream of air that passes5) The closing of vocal cords is due to:a. vibrationb. elasticity of vocal cordsDIAGNOSTIC TESTS AND PEDIAGNOSTICSIndirect laryngoscopy- open up mouth, examiner grasps the protruded tongue, insert laryngeal mirror- downside if the px has strong gag reflex, it will be hard to do

Laryngeal telescope- advantage: easier, brighter, view is magnified;- downside if the px has strong gag reflex, it will be hard to do- laryngeal telescope cost 2000$

Flexible fiberoptic laryngoscope- flexible scope insert thru the nose- flexible scope cost 10,000$

Direct microlaryngoscopy- Main indication taking out nodules and cyst in larynx- px is put to sleep and the laryngoscope is inserted thru the mouth.- Under general anesthesia- done for surgery of vocal cord and larynx

Laryngeal videostroboscopy- observe the vibration of the vocal fold through flashes of light.- early lesions are detected

History and physical examinationComplaint or PE findingsLaryngeal problem

Hoarsenessbecause of problem in phonation (think ofstructures involved in phonation)

Difficulty of breathing;problem in inspiration

due to the larynxs anatomical function inairway protection

Cherry red epiglottis

Dryness

Check hydration historyMedications that may cause dryness

Voice handicap index- a questionnaire by which a px can rate the severity of voiceproblem** Observe great care in PE to avoid spasmGENERAL RULE IN MEDICINE: Function of organ dictates its S/Sx