INTRINSIC Muscles of Larynx Unit 2

intrinsic muscles include

adductors, abductors, glottal tensors, relaxors, auxiliary

intrinsic muscles both origin and insertion is found on?

laryngeal cartilages

intrinsic muscles make fine adjustments to?

vocal mechanism

lateral cricoarytenoid (LCA)

origin: upper border of anterolateral arch of cricoid

course: superior and posterior

insert: muscular process and anterior surface of arytenoid

action: moves muscular process forward, inward/downward

impact on vocal folds: resulting in rotate vocal process, towards midline (adducting), possibly lengthen, increases medial compression

transverse interarytenoids

origin: lateral margin and posterior surface of arytenoid

course: horizontal, laterally

insert: lateral margin and posterior surface of opposite arytenoid

action: approximate arytenoids via sliding

impact on vocal fold: approximation (adduction), medial compression

oblique interarytenoids

origin: posterior surface of muscular process of one arytenoid

course: obliquely, up

insert: near apex of opposite arytenoid

action: pulls apex medially, rocks arytenoid down/in

impact on vocal folds: adduction, medial compression

Action of oblique interarytenoids?

action pulls apex medially approximate arytenoids, rocks arytenoid down/in

What is the impact of oblique interarytenoids on vocal folds?

adduction, medial compression

Posterior cricoarytenoid (PCA)

origin: shallow depression of posterior aspect of quadrate lamina of cricoid cartilage

course: superior and lateral

insert: fibers converge to muscular process of arytenoid cartilages

action: vertical fibers rotate arytenoid so that vocal processes abducted and elevated, rocks the vocal folds

impact on vocal folds: abduction, dilation of larynx

Posterior cricoarytenoid action?

vertical fibers rotate arytenoid so that vocal processes abducted and elevated

Impact of Posterior cricoarytenoid on vocal folds?

abduction

cricothyroid (CT)

origin:  anterolateral arch of cricoid cartilage

pars oblique

course: obliquely, up

insert: thyroid cartilage b/w laminae and inferior horns

action: depress thyroid

pars recta

course: up and out

insert: lower margin of thyroid lamina

action: depress thyroid

impact of cricothyroid on vocal folds?

pulls thyroid down (tilt) relative to cricoid, lengthened and tensed (stretched)

thyroarytenoid (TA)

makes up main mass of vibrating vocal folds

consists of two muscles masses

portion just lateral to vocal ligament is vocalis or thyrovocalis

lateral to vocalis thryomuscularis

thyrovocalis (vocalis)

origin: inner surface of thyroid cartilage near notch

course: posterior

insert: vocal process and lateral surface of arytenoid cartilages

action: draws thyroid and cricoid farther apart in front

impact on vocal folds: tenses

thyromuscularis

origin: inner surface of thyroid cartilage near notch lateral to vocalis

course: posteriorly, parallel to vocalis

insert: base and muscular process of arytenoids

action: similar to LCA

impact on vocal folds: relaxes vocal folds, provides cushioning, and elasticity to VF

Aryepiglottic

origin: apex of arytenoid

course: superior/laterally within the aryepiglottic fold

insert: lateral border of epiglottis

action: helps close epiglottis and constrict airway

thyroepiglottis

origin: inner angle of thyroid cartilage

course: back and up

insert: lateral edges of epiglottis

action: dilates airway