larynxxx
TRANSCRIPT
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
$
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.
END
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.