The Larynx

Larynx-organ that provides a protective sphincter at the inlet of the air passages

-responsible for voice production

-opens above into the laryngopharynx, and below with the trachea

-covered in front by the infrahyoid strap muscles and at the sides by the thyroid gland

Location

-situated below the tongue and hyoid bone, between the great blood vessels of the neck-lies at the level of the 4th, 5th, and 6th cervical vertebrae

Cartilages of the Larynx

Thyroid Cartilage

-largest -consists of 2

laminae of hyaline cartilage

-posterior border extends upward into a superior cornu and downward into an inferior cornu

Cricoid Cartilage

-formed of hyaline cartilage

-shaped like a signet ring

-lies below the thyroid

cartilage

Arytenoid Cartilages

- paired, pyramid-shaped cartilages

-located at the back of the larynx

-articulate with the upper border of the lamina of the cricoid cartilage

-Each cartilage has:•apex- articulates

with the small corniculate cartilage

•vocal process- projects forward and gives attachment to the vocal ligament

•muscular process- projects laterally & gives attachment to the posterior and lateral cricoarytenoid

Corniculate Cartilages

-paired conical cartilages

-gives attachment to the aryepiglottic fold

Cuneiform Cartilages

-paired, small rod-shaped cartilages

-found in thearyepiglotticfolds

Epiglottis

-leaf-shaped lamina of elastic cartilage lies behind the root of the tongue

Attachments:• stalk - back of the thyroid cartilage • sides - arytenoid cartilages by the aryepiglottic folds of

mucous membrane• upper edge - free • The covering of mucous membrane passes forward

onto the posterior surface of the tongue as the median glossoepiglottic fold

• Vallecula - depressions on each side

Membranes and Ligaments of the Larynx Thyrohyoid membrane

-connects the upper margin of the thyroid cartilage to the hyoid bone

-midline is thickened to form the median thyrohyoid ligament

-pierced on each side by the superior laryngeal vessels and internal laryngeal nerve from superior laryngeal nerve

Cricotracheal Ligament

-connect the cricoid cartilage to the first ring of the trachea

Quadrangular Membrane

- extends between the epiglottis and the arytenoid

- thickened inferior margin forms the vestibular ligament - the vestibular ligaments form the interior of the vestibular folds

Cricothyroid Ligament

•Lower Margin-attached to the upper border of the

cricoid cartilage

•Superior Margin-ascends on the medial surface of the

thyroid cartilage

-upper free margin composed of elastic tissue which forms the important vocal ligament on each side• anterior end - thyroid cartilage• posterior end - arytenoid cartilage

-vocal ligaments form the interior of the vocal folds (vocal cords)

Inlet of the Larynx (Laryngeal aditus/Laryngeal aperture)

-opening is wider in front than behindBoundaries:

•Anterior- Epiglottis

•Lateral- Aryepiglottic fold

•Posterior- Arytenoid cartilages & Corniculate cartilages

Piriform Fossa

-recess on either side of the fold and inlet

Boundaries:Medial- Aryepiglottic fold

Lateral- Thyroid cartilage & Thyrohyoid membrane

Laryngeal Folds

Vestibular Fold

-fixed fold on each side of the larynx

-formed by mucous membrane covering thevestibular ligament

-vascular and pink in color

Vocal Fold (Vocal Cord)

-mobile fold on each side of the larynx

-concerned with voice production

-formed by mucous membrane covering the vocal ligament

-avascular and white in color

Boundaries:Medial- Aryepiglottic fold

Lateral- Thyroid cartilage & Thyrohyoid membrane

-moves with respiration

•Rima glottidis/glottis - gap between the vocal folds; narrowestpart of the larynx and measures about 2.5 cm from front to

back in the male adultand less in the female. In children, the lower part of the larynx within the cricoid cartilage is the narrowest part

Boundaries:Anterior- Vocal Folds

Posterior- Arytenoid cartilages

Cavities of the Larynx

-extends from the inlet to the lower border of the cricoid cartilage

divided into threeregions:

•vestibule - between inlet andvestibular folds• middle region - between vestibular folds above and vocal folds below• lower region - between vocal foldsabove and lower border of the cricoid cartilage below

Sinus of the Larynx

-paired small recesses lined withmucous membrane between thevestibular and vocal folds

Saccule of the Larynx

-a diverticulum of mucous membrane that ascends from thesinus; mucous secretion lubricatesthe vocal cords

Muscles of the Larynx

-divided into two groups

Extrinsic

- moves the larynx up and down during swallowing

Muscles of the Larynx

•Elevation:Digastric Stylohyoid Mylohyoid

Geniohyoid StylopharyngeusSalpingopharyngeus Palatopharyngeus

•Depression:Sternothyroid Sternohyoid Omohyoid

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Movements of the Vocal Folds with Respiration• Quiet inspiration

-vocal folds are abducted and glottis is triangular

• Expiration

-vocal folds are adducted

• Deep inspiration

- vocal folds are maximally abducted and glottis is diamond shaped because of the maximal lateral rotation of the

arytenoid cartilages

Sphincteric Function of the Larynx

-two sphincters in the larynx

• sphincter at the inlet is used only during swallowing

epiglottis - serves as a cap over the laryngeal inlet

• rima glottidis serves as a sphincter in coughing or sneezing

intrathoracic pressure rises; vocal folds are suddenly abducted; Valsalva maneuver, forced expiration takes place against a closed glottis

Voice Production in the Larynx

-intermittent release of expired air between the adducted vocal folds results in their vibration and in the production of sound

• Frequency/pitch - length and tension of the vocal ligaments

• Quality - resonators above the larynx, namely, the pharynx, mouth, and paranasal sinuses; it is controlled by the muscles of the soft plate, tongue, floor of the mouth, cheeks, lips, and jaws

Voice Production in the Larynx

• Speech - intermittent release of expired air between the adducted vocal folds

• Singing - prolonged release of the expired air between the adducted vocal folds

• Whispering - the vocal folds are adducted, but the arytenoid cartilages are separated

Mucous Membrane of the Larynx

• Cavity – lined by ciliated columnar epithelium

• Vocal cords – lined by stratified squamous epithelium

Nerve Supply of the Larynx

• Sensory Nerves• Above the vocal cords: internal laryngeal branch of

the superior laryngeal branch of the vagus nerve• Below the level of the vocal cords: recurrent

laryngeal nerve• Motor Nerves• All: recurrent laryngeal nerve except cricothyroid

muscle which is supplied by external laryngeal branch of the superior laryngeal branch of the vagus nerve

Blood Supply of the Larynx

• Upper half of the larynx: superior laryngeal branch of superior thyroid artery

• Lower half of the larynx: inferior laryngeal branch of inferior thyroid artery

- deep cervical lymph nodes

Lymph Drainage of the Larynx

Lesions of the Laryngeal Nerves

• Involves recurrent laryngeal nerves and external laryngeal nerve which are vulnerableduring operations on the thyroid gland

• left recurrent laryngeal nerve may be involved in a bronchial or esophagealcarcinoma or in secondary metastatic deposits in the mediastinal lymph nodes

Clinical Notes

• right and left recurrent laryngeal nerves may be damaged by malignant involvement of the deep cervical lymph nodes– Section of the external laryngeal nerve

- weakness of the voice because the vocalfold cannot be tensed. The cricothyroid muscle is paralyzed

– Unilateral complete section of the recurrent laryngeal nerve- Speech is not greatly affected

- Bilateral complete section of the recurrent

laryngeal nerve

- Breathing is impaired; speech is lost

Clinical Notes

•Cricothyroidotomy - primary purpose is to provide an

emergency breathing passage for a patient whose airway is closed by traumatic injury to the neck.

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Edema of the Laryngeal Mucous Membrane

- accumulation of tissue fluid causes the mucous membrane above the rima glottidis to swell and encroach on the airway. – In severe cases, a

cricothyroidotomy or tracheostomy may be necessary.