Larynx - cartilaginous structure holding the vocal folds which protrude into airstream

Transcription

1 1! Larynx - cartilaginous structure holding the vocal folds which protrude into airstream 2! Flow increase - like thumb over garden hose Pressure drop - narrower space forces pressure drop due to speed of air Voiced - voiceless sounds PhonationAnatomy glottis, subglottal region, Biological function -protection of airway -seal during swimming -seal to provide base for muscles 3! 4!

2 One cycle of vocal fold vibration A. Air from lungs hits adducted folds B. Pressure parts folds inferiorly C. Superior aspects of folds opens D. Folds blown apart, flow between folds increases and pressure decreases E. Decreased pressure and elastic quality of folds causes folds to return toward midline F. Folds make contact inferiorly G. Vibration cycle completed Although specific muscles cause movement, actual vibration is product of airflow interacting with tissue in absence of repetitive muscle contraction 5! 6! Three paired and three unpaired cartilages Tube with smooth and reasonably aerodynamic surface 1. Cricoid - ring shaped, narrow anteriorly Sheets and cords of ligaments connect cartilages with smooth mucous 2. Thyroid - articulates with cricoid through paired processes which let it rock membrane covering medial-most surface forward and backward, anterior vocal fold attachment Thyrohyoid membrane, lateral thyrohyoid ligament, and median thyrohyoid 3. Arytenoids (paired) - posterior point for attachment of vocal folds ride ligament cover space between hyoid and thyroid upon posterior portion of cricoid cartilage Hyoepiglottic and thyroepiglottic ligaments attach epiglottis to the hyoid and 4. Corniculates (paired) - rest upon arytenoids thyroid 5. Cuneiforms (paired) - rest within the aryepiglottic folds atop corniculates Cricotracheal ligament attaches trachea to larynx 6. Epiglottis - medial to thyroid and hyoid - protective as it covers larynx Ventricle folds (false) and vocal folds separated by laryngeal ventricle 7! 8!

3 9! 10! 11! 12! Five layers 1. Squamous epithelium - extremely thin - gives vocal folds the pearly white appearance 2. Lamina propria a. Elastin fibers - random orientation allowing stretching b. Elastin fibers - anterior/posterior orientation c. Collagen fibers - anterior/posterior orientation but prohibits extension 3. Thyrovocalis muscle Some authors mucosal lining - 1 and 2a layer vocal ligament - 2b and 2c (giving stiffness and structure) Other authors cover - 1, 2a and 2b body - 2c and 3

4 Valleculae - little valleys formed by membrane between tongue and epiglottis Glottis - space between folds, usually approximately 20mm in adults Anterior commissure - anterior most opening Posterior commissure - between the arytenoid cartilages Cuneiform cartilages - embedded within the aryepiglottic folds - provide support for membranous covering 13! 14! Viewed as expanded tracheal cartilage Would loosely fit on little finger 15! 16!

5 Arytenoids - one of most important of larynx rest on posteriolateral surface of cricoid 1. apex - below corniculate cartilages 2. base - inferior surface is concave and articulates with convex arytenoid facet of cricoid 3. Vocal process - projects anteriorly toward thyroid notch and serves as attachment for vocal folds (thyrovocalis muscle) 4. Muscular process - attachment for muscles which adduct and abduct folds (thyromuscularis muscle) Union between tongue and larynx (although not bone of larynx) -articulates loosely with superior cornu of thyroid -only bone in body not attached to another bone 17! 18! 1. Cricothyroid joint - synovial joint of cricoid and inferior cornu of thyroid -permits thyroid to rock down in front and slightly glide forward and backward -provides major adjustment for changes in vocal pitch 2. Cricoarytenoid joint - synovial joints between concave arytenoid base and convex cricoid cartilage -permits rocking, gliding and minimal rotation A. Arrows show rocking movement as result of articular facet B. Long axis of facet allows permits anterior/posterior gliding C. May also rotate. 19! 20!

6 Origin - superior-lateral surface of cricoid cartilage Insertion - muscular process of the arytenoid Innervation - X (vagus), recurrent laryngeal nerve, inferior laryngeal nerve Function - adducts vocal folds, increases medial compression 21! 22! 23! 24! Transverse arytenoids Origin - lateral margin of posterior arytenoid Insertion - lateral margin of posterior surface opposite arytenoid Innervation - X (vagus), recurrent laryngeal nerve Function - adducts vocal folds Oblique arytenoids Origin - posterior base of muscular process of arytenoid Insertion - apex of opposite arytenoid Innervation - X (vagus), recurrent laryngeal nerve Function - pull apex medially

7 Posterior Cricoarytenoids Origin - posterior cricoid lamina Insertion - posterior aspect of muscular process of arytenoid Innervation - X (vagus), recurrent laryngeal nerve Function - abducts vocal folds 25! 26! Cricothyroid pars recta Origin - anterior surface of the cricoid beneath arch Insertion - thyroid between lamina and inferior horns Innervation - External branch of superior laryngeal nerve of X (vagus) Function - depress thyroid relative to cricoid, tense vocal folds Cricothyroid pars oblique Origin - cricoid lateral to pars recta Insertion - lower surface of thyroid lamina Innervation - External branch of superior laryngeal nerve of X (vagus) Function - depress thyroid relative to cricoid, tense vocal folds 27! 28!

8 Thyrovocalis (medial thyroarytenoid) Origin - inner surface thyroid cartilage near notch Insertion - lateral surface of arytenoid vocal process Innervation - X (vagus) recurrent laryngeal nerve Function - tense vocal folds Thyromuscularis (lateral thyroarytenoid) Origin - inner surface thyroid cartilage near notch Insertion - muscular process and base of arytenoid cartilage Innervation - X (vagus) recurrent laryngeal nerve Function - relaxes vocal folds Superior thyroarytenoid (thyroepiglottis) Origin - inner surface thyroid cartilage near angle Insertion - muscular process of arytenoid cartilage Innervation - X (vagus) recurrent laryngeal nerve Function - relaxes vocal folds Thyroepiglottis: also known as the superior thyroarytenoid muscle. Some anatomists say this muscle is not present in all individuals. It originates higher on the internal surface of the thyroid cartilage and has a more oblique direction back down toward the muscular process of the arytenoid where it inserts. When present this muscle seems to serve as a relaxer of the vocal fold. It may also possibly be responsible for changing and controlling the internal dimensions of the epilarynx and false vocal folds. 29! 30! 31! 32!

9 Diagastricus anterior (also considered muscles of mastication) Stylohyoid Origin - inner surface of mandible near symphysis Origin - styloid process of temporal bone Insertion - hyoid (by means of intermediate tendon) Insertion - corpus hyoid Innervation - Cranial V (Trigeminal), mandibular branch (via mylohyoid branch of Innervation - Cranial VII (Facial), motor branch Function - elevates and retracts the hyoid bone inferior alveolar nerve Function - draw hyoid up and forward Diagastricus posterior (also considered muscles of mastication) Origin - mastoid process of temporal bone Insertion - hyoid (by means of intermediate tendon) Innervation - Cranial VII (Facial), digastric branch Function - draw hyoid up and back Together these elevate hyoid 33! Mylohyoid 34! Geniohyoid Origin - inner surface of mandible, mylohyoid line Origin - inner surface of mandible, mental spines Insertion - corpus hyoid Insertion - corpus hyoid Innervation - Cranial V (Trigeminal), mandibular branch Innervation - Cranial XII (hypoglossal) and C1 spinal Function - elevates hyoid and depresses mandible Function - elevates hyoid and depresses mandible 35! 36!

10 Hyoglossus Genioglossus Origin - greater cornu of hyoid Origin - inner surface of mandible, mental spines Insertion - side of tongue Insertion - tongue and corpus hyoid Innervation - Cranial XII (hypoglossal) motor branch Innervation - Cranial XII (hypoglossal) motor branch Function - elevate hyoid depresses tongue Function - elevate hyoid depresses, retracts and protrudes tongue 37! 38! 39! 40! Inferior Pharyngeal Constrictor (Thyropharyngeus) Origin - posterior pharyngeal raphe Insertion - thyroid lamina and inferior cornu Innervation - X (vagus) recurrent laryngeal nerve (external laryngeal branch) and X superior laryngeal nerve (pharyngeal branch) and XI (Accessory) Function - elevates and constricts pharynx

11 Sternohyoid Origin - manubrium sterni and clavicle Insertion - inferior margin of hyoid corpus Innervation - ansa cervicalis from C1-C3 Function - depresses hyoid Omohyoid, superior and inferior heads Origin - superior - corpus hyoid Inferior - upper border of scapula Insertion - corpus hyoid Innervation - ansa cervicalis from C1-C3 Function - depresses hyoid Sternothyroid Origin - manubrium sterni Insertion - oblique line thyroid cartilage Innervation - spinal nerves C1-C3 Function - depresses thyroid cartilage Thyrohyoid Origin - oblique line thyroid cartilage Insertion - greater cornu hyoid Innervation - Cranial XII (hypoglossal) and fibers from spinal C1 Function - depresses hyoid and elevate thyroid 41! 42!