Anatomy Quiz #2

Vocal fold length for females

12 to 17 mm in length

Vocal fold length for males

17 to 25 mm in length

Functions of the larynx

• protective/survival

  • close off to protect lower airway

  • opening to aid respiration

  • thoracic fixation - lifting objects

• sound source for voice production

The two cartilages of the larynx

• hyaline cartilage

• elastic cartilage

Hyaline cartilage

• flexible and elastic properties

• made up of collagen and other proteins

• forms the thyroid, cricoid and arytenoid cartilages

Elastic cartilage

• similar to hyaline

• matrix contains a network of branched yellow elastic fibers

• flexible and can withstand bending

• forms the epiglottis

Hyoid bone

• important site for the muscular attachments of the larynx via the suprahyoid and infrahyoid muscles

• attached to the tongue via a ligament called the glossoepiglottic ligament

Thyroid cartilage

• largest unpaired cartilage in the laryngeal framwork

• 2 laminae

• 2 superior cornu/horn to hyoid

• 2 inferior cornu/horn

• an oblique line

• a sup thyroid notch

• adam’s apple

  • men = 90 degree ant angle

  • women = 120 degree ant angle

Cricoid cartilage

• single cartilage made of hyaline tissue

• connected to the thyroid cartilage via inf horn and superiorly by the cricothyroid membrane

• attaches to the first tracheal ring by the cricotracheal ligament or membrane

Cricothyroid joint

• allow the thyroid to rotate anteriorly or posteriorly on the cricoid cartilage

• near the pars oblique & pars recta

Arytenoid cartilages

• paired

• on the sup margin of the cricoid lamina consisting of hyaline and elastic tissue

• pyramidal shaped

• has two processes

  • vocal process

  • muscular process

• serve as the posterior attachment for the false vocal folds

• connected to the epiglottis by the aryepiglottic muscle to the thyroid cartilage anteriorly by the vocal ligament

Arytenoid cartilages: vocal process

attachment site of the vocal ligament

Arytenoid cartilages: muscular process

where the posterior & lateral cricoarytenoid muscles attach

Arytenoid cartilages movement

• allow for abduction and adduction

  • bc of the cricoarytenoid joint

• sit on top of the cricoid cartilage

• cricoarytenoid joint allows the arytenoid joints to slide medially and rock at these joints

Corniculate cartilages

• paired

• mounted on top of the arytenoid cartilages

• no role in voice production

Cuneiform cartilage

• paired

• small, rod shaped elastic cartilage embedded in the aryepiglottic muscle/fold

Epiglottis

• sup part of the larynx

• posterior to the hyoid bone and base of tongue

• leaf shape, broad on top & narrow at base

  • aka the petiolus

• composed of elastic cartilage

Epiglottis movement

• downward movement to closure is the effect of

  • hyolaryngeal movement

  • downward bolus movement

  • tongue base retraction

• attaches to the angle of the thyroid cartilage by a ligament called the thyroepiglottic ligament

• attaches to the tongue by the glossoepiglottic ligaments

• attaches to the lower part of the ant surface to the body of the hyoid bone called the hyoepiglottic ligament

Extrinsic muscles of the larynx

• support and adjust position of larynx

  • elevate and depress

• one attachment to the hyoid bone

• 4 above hyoid - suprahyoid - paired

• 4 below hyoid - infrahyoid - paired

Suprahyoid muscles

• elevate the hyoid bone and larynx with other functions

• the muscles are

  • diagastric

  • mylohyoid

  • stylohyoid

  • geniohyoid

Diagastric

• two muscular bellies (ant & post) which are joined by an intermediate tendon

• ant belly pulls hyoid forward & upward

• post belly pull the hyoid back and upward

Mylohyoid

• form the muscular floor of the mouth

• elevates the floor of the mouth and tongue, depress the jaw as long as the hyoid is stabilized

Stylohyoid

• pulls hyoid up and back

• during swallowing fixes the hyoid bone for infrahyoid action

Geniohyoid

• elevates the hyoid gone, raises the floor of the mouth for swallowing and depresses the mandible when hyoid is stabilized

Infrahyoid muscles

• depress the hyoid and larynx with its other functions

• the muscles are

  • sternohyoid

  • sternothyroid

  • omohyoid

    • inf belly

    • sup belly

  • thyrohyoid

Sternohyoid

• attaches the hyoid bone to the sternum

• depresses the hyoid and larynx

Sternothyroid

• deep to sternohyoid

• originates from manubrium; inserts into the oblique line of thyroid cartilage

• depresses the larynx

Omohyoid

• superior and inferior belly connected by intermediate tendon

• depress the hyoid and larynx

Thyrohyoid

• continuation of the sternothyroid muscle

• moves hyoid closer to larynx

Intrinsic muscles of the larynx

• five

• paired and have both attachments within the larynx

• regulate the tension in the vocal ligament and size/shape of the glottal space

Interarytenoids

• oblique fibers

• transverse fibers

• both fibers adduct the vocal fold when contracted

Interarytenoids: oblique fibers

origin on the posterolateral surface of the aryt

Interarytenoids: transverse fibers