Larynx Flashcards
Functions of the larynx
-maintains a patient airway
-protects the lower respiratory tract
-phonation
What does the larynx consist of
-cartilaginous skeleton
-membranes
-muscles
One bone 9 cartilages
Thyroid cartilage (adams apple)
-located at the level of the 4th vertebrae
-laminae x2
-superior horns x2
-inferior horns x2
-thyroid notch
Cricoid cartilage
-located at the level of the 6th cervical vertebrae
-forms a complete ring
-arch (anterior)
-lamina (posterior)
-articular facets
Epiglottis
-leaf shaped
-attached to posterior aspect of the anterior angle of the thyroid cartilage
-extends upwards and backwards behind tongue
-covers the laryngeal inlet during swallowing
Arytenoid cartilages
-pryamidal in shape- apex, base, 3 surfaces
-muscular process- where muscles attach
-vocal process- where vocal cords attach
-rotates around vertical axis and slides on the slope of the cricoid lamina
Membranes
-the laryngeal skeleton is lined by three membranes
-thyroid, quadrangular, cricovocal
Thyroid membrane
-extends from thyroid cartilage to hyoid bone
-thickened to form medial and lateral thyrohyoid ligaments
Quadrangular membrane
-extend from body and apex of arytenoids to lateral edge of epiglottis
-the free upper border forms the aryepiglottic fold- one on either side forming the boundary of the laryngeal inlet
-the free lower border forms the vestibular fold (false vocal cord)
Cricovocal membrane
-attaches inferiorly to cricoid cartilage
-attaches superiorly to thyroid angle and to the vocal processes of the arytenoids
-the free upper border forms the vocal fold (true vocal cord)
Regions of the larynx
-laryngeal inlet:opening into larynx
-glottis:space between the tow vocal cords
-supraglottic cavity (vestibule) : between inlet and vestibular folds
-laryngeal ventricles (sinuses): between vestibular and vocal folds. Saccule extends laterally
-infraglottic cavity: between vocal folds and inferior border of cricoid cartilage
Mucosa (lining/ covering) of the larynx
-superglottic and infraglottic cavities- respiratory epithelium, seromucous glands
-vestibular folds- respiratory epithelium, mucous glands
-ventricle- respiratory epithelium, saccule contains mucous glands
-vocal folds- stratified squamous epithelium in areas of contact-no mucous glands
What are the extrinsic muscles of the larynx
- move the whole larynx
-longitudinal pharyngeal muscles
Extrinsic- infrahyoid muscles
-the infrahyoid muscles originate below and insert onto the hyoid bone
-they depress and fix the hyoid bone and larynx
-superior belly omohyoid, inferior belly of omohyoid (omo=shoulder), thryohyoid, sternothyroid, sternohyoid
Extrinsic- suprahyoid muscles
-originate above and insert onto the hyoid bone
-if the mandible is fixed they elevate the hyoid bone and larynx
-if the hyoid bone is fixed they depress the mandible
-mylohyoid, geniohyoid, anterior belly of digrastic, posterior belly of diagrastic
What do Intrinsic muscles do
Alter positon, length and tension of the vocal cords and narrow the laryngeal inlet
Intrinsic muscles abductor of vocal cords
Posterior circoarytenoid
Intrinsic muscles adductors of vocal cords
Lateral cricoarytenoid and transverse arytenoid
Intrinsic muscles
Narrower of laryngeal inlet
Aryepiglottic and oblique arytenoid
Intrinsic muscles
Tensor of vocal cords
Cricothyroid
Intrinsic muscles
Relaxer of vocal cords
Thryoarytenoid
What does abduction and adduction of the vocal cords do to the glottis
Alters the size of the glottis
Posterior cricoarytenoid
Origin- cricoid lamina
Innervation-muscular process of arytenoid
A-rotates arytenoid backwards therefore abducts vocal cords and opens the glottis
Lateral cricoarytenoid
Origin- lateral surface of cricoid
Innervation- muscular process of arytenoid
A-rotates arytenoid forward therefore adducts vocal cords and closes the glottis
What does simultaneous contraction of lateral and posterior cricoarytenoid muscles do
Seperates the arytenoids by sliding them down the cricoid lamina
Transverse arytenoids
Connects the bodies of the arytenoid cartilages
Approximates the arytenoids therefore closes the rima glottidis
Oblique arytenoid and aryepiglottic muscles
-oblique arytenoid: passes from muscular proces of one arytenoid to apex of the other
-aryepiglottic: continuation of the oblique arytenoid that inserts into the side of the epiglottis
-acts as a sphincter of the laryngeal inlet during swallowing
Cricothyroid
O-thyroid cartilage
I- anterolateral aspect of cricoid cartilage
A-elevates arch of cricoid and tips the lamina backwards therefore increases length and tension of vocal cords and raises pitch of voice and narrows the glottis
Thryoarytenoid
O-thyroid cartilage
I-vocal process and body of arytenoid
A-draws arytenoid forwards therefore relaxes vocal cords
Vocalis-the part of the thyroarytenoid that lies in free edge of vocal fold modified tension with the fold
Innervation of the larynx
-receives both somatic motor and general sensory innervation
-supplied by branches of the vagus nerve (CN X)
-right and left superior laryngeal
-right and left recurrent laryngeal
Superior laryngeal nerve
-divides into external and internal laryngeal branches
-external laryngeal- motor to cricothyroid muscle
-internal laryngeal- transmits general sensation from above the vocal cords
Recurrent (goes back on itself) laryngeal nerve
-provides motor innervation to all intrinsic laryngeal muscles except cricothyroid
-transmits general sensation from below the vocal cords
-the left recurrent laryngeal nerve wraps around the arch of aorta in the thorax and then ascends back to neck
Blood supply of the larynx
-laryngeal branches of the superior and inferior thyroid arteries
-laryngeal veins- superior and middle
-thyroid veins- internal jugular vein
