Phonation 1 Hyoid Bone Laryngeal Cartilages

hyoid bone

part of axial skeleton (not part of larynx, larynx suspended from it), not attached to any other bone, suspended by stylohyoid ligaments, inferior attachment for bulk of tongue musculature, 22 or 23 muscles either take their origin from or insert into ____, many important for speech, serves as superior attachment for some extrinsic laryngeal muscles, u-shaped, limbs of u directed backward and slightly upward, found in upper neck at level of C3

corpus of hyoid bone

bulk of hyoid bone, unpaired ventral structure, roughly quadrilateral in shape, anterior surface is convex, posterior surface is concave, point of attachment for muscles

greater cornua (horns) of hyoid bone

posteriorly and superiorly directed limbs projecting from lateral borders of corpus, terminate as tubercles which articulate indirectly and loosely with the superior horns of the thyroid cartilage, points of attachment for muscles

lesser cornua (horns) of hyoid bone

superiorly directed, cone-shaped prominence, found at junction of greater horn/corpus, usually capped by small cone-shaped elastic cartilages, points of attachment for muscles

larynx

as a structure: unpaired, midline; musculocartilaginous, suspended from hyoid bone, terminates at trachea, anterior neck region, C3-C6 (position varies with age, sex, head position, and laryngeal activity), “adam’s apple,” both biological and nonbiological function

biological functions of the larynx

intrinsic component of respiratory system, thoracic fixation, protective device (valve) for the lower respiratory tract

thoracic fixation

prevents air escape; facilitates activities demanding highly elevated abdominal pressures

protective device (valve) for the lower respiratory tract

active closure prevents substances from entering larynx, expels foreign objects: sudden active dilation of laryngeal valve, following an elevation in pressure → coughing

nonbiological functions of the larynx

sound production, can be a sound generator only when its not fulfilling its vital biological functions, provides a mechanical variable resistance to the flow of air into and out of the lungs, extraordinarily versatile, rapid & subtle adjustments → sound production over very wide range of pitch & loudness

cartilaginous framework of larynx

9 cartilages and their connecting membranes and ligaments, 3 unpaired and rather large cartilages (1 thyroid/hyaline, 1 cricoid/hyaline, 1 epiglottis/elastic), 3 paired and smaller cartilages (2 arytenoid/hyaline, 2 corniculate/elastic, 2 cuneiform/elastic)

3 unpaired laryngeal cartilages

thyroid (hyaline)

cricoid (hyaline)

epiglottis (elastic)

3 paired laryngeal cartilages

arytenoid (hyaline)

corniculate (elastic)

cuneiform (elastic)

thyroid cartilage

largest laryngeal cartilage, composed of 2 quadrilateral plates

thyroid lamina

quadrilateral plate, fuse at midline anteriorly at thyroid angle, not completely fused in superior portion → v-shaped thyroid notch, just below thyroid notch is thyroid prominence (Adam’s apple), form most of the anterior and lateral walls of the larynx

thyroid angle

thyroid lamina fuse at midline anteriorly at _____

v-shaped thyroid notch

thyroid lamina not completely fused in superior portion

thyroid prominence

Adam’s apple, just below thyroid notch

oblique line of thyroid

prominent ridge that courses obliquely along the surface

oblique tendon of the thyroid

may be found on oblique line, point of attachment for muscles

foramen of thyroid cartilage

found in ~1/3 of thyroid cartilages, posterosuperior quadrant of lamina, extremely variable in dimensions, often provides blood vessels access to the interior of the larynx

superior cornua (horns) of the thyroid cartilage

directed upward, backward, and medially, longer and more slender, articulate indirectly with the greater cornua of hyoid bone via lateral hyothyroid ligaments (thickenings of the hyothyroid membrane), variable in size & shape, one is absent in ~5% of the population

lateral hyothyroid ligament

the superior cornua articulate indirectly with the greater cornua of the hyoid bone via ______________

inferior cornua (horns) of the thyroid cartilage

directed down and slightly medially, shorter and thicker than superior horns, articulate with the cricoid cartilage via articular facets located on medial surface of each tip, held in place by the capsular ligaments, comprised of the anterior, posterior, and lateral ceratocricoid ligaments

cricoid cartilage

located immediately above the uppermost tracheal ring; articulation is via the cricotracheal ligament, serves as base of larynx, smaller, stouter than thyroid, consists of anterior arch and posterior quadrate lamina, parts are continuous and form a ring

posterior quadrate lamina

part of the cricoid cartilage, the “signet” of a ring, extends upward; occupies a portion of the space between the posterior margins of the thyroid cartilage, prominent vertical ridge at midline separating two shallow depressions → attachment of the posterior cricoarytenoid muscles, articular facets on superior surface that unite with arytenoids

cricoid arch

the anterior “band” of the ring, lies immediately below the angle of the thyroid, where the arch meets the posterior quadrate lamina are small oval articulator facets → inferior cornua of the thyroid which form the cricothyroid joints

epiglottis

prevents food from entering the larynx during swallowing, contributes very little to the production of speech, flexible leaf-shaped structure, composed of elastic cartilage, corpus is located just behind the hyoid bone and root of tongue, broad part is corpus, narrows into a stalk-like structure called the petiolus, anterior surface is convex and relatively smooth, posterior surface is concave and pitted, anterior surface of corpus is continuous with root of tongue by way of one medial and two lateral glossoepiglottic folds, between the medial and lateral folds are two pits called valleculae

hyoepiglottic ligament

attaches the corpus of the epiglottis (at its most broad point) to the inner surface of the corpus of hyoid bone

thyroepiglottic ligament

attaches the petiolus to the thyroid angle, just behind and beneath the thyroid notch

arytenoid cartilages

paired cartilages, located on the posterolateral sloping border of the posterior quadrate lamina of the cricoid, roughly resemble 3-sided pyramid, with a base and apex

medial surfaces of the arytenoids

face each other, nondescript

posterior surfaces of arytenoids

same plane as cricoid’s posterior quadrate lamina, house some muscles

_____ and _____ surfaces of the arytenoids are at a 90 degree angle

medial; posterior

anterolateral surfaces of the arytenoids

proceeds from medial to lateral surfaces, most extensive and complex, has 2 fovea (pits) (triangular fovea - near apex, fovea oblonga - near base), arcuate ridge - horizontally directed and separates the fovea, fovea serve as points of attachment for muscles

muscular process of arytenoids

laterally directed, juncture of anterolateral and posterior surfaces, has a concave and rounded articulator facet on undersurface for articulation with the cricoid, point of attachment for some important laryngeal muscles

vocal process of arytenoids

anteriorly/medially directed, found at juncture of anterolateral and medial surface, vocal ligament - an important part of vocal fold inserts on each vocal process

aryepiglottic folds

where the cuneiform and corniculate cartilages are found, folds of mucous membrane that form entrance to larynx, run from the lateral borders of corpus of the epiglottis to the arytenoid cartilages

corniculate cartilages

pair of conical elastic cartilages, cap the apexes of the arytenoid cartilages, embedded within the aryepiglottic folds and appear as bumps

corniculate tubercles

bumps that are created by the corniculate cartilages embedded within the aryepiglottic folds

cuneiform cartilages

paired, embedded in aryepiglottic folds and appear as bumps, anterolateral to the corniculate cartilages, lend support to and stiffen aryepiglottic folds to help maintain the opening of larynx

cuneiform tubercles

bumps created by the cuneiform cartilages as they are embedded in aryepiglottic folds