larynx Flashcards
functions of larynx
1: regulate passage of materials through the airway (acts like valve)
2: for voice production
what are the components of the laryngeal skeleton?
nine cartilages (3 paired, 3 unpaired) joined by membranes and ligaments hyoid bone not part of larynx, but has supportive role for some of the ligaments includes: epiglottis thyroid cartilage arytenoid cartilage cricoid cartilage tracheal rings
embryological origin of larynx
cartilages and intrinsic muscles derived from mesenchyme of 4th and 6th arches
mucous membrane from endoderm
overall, larynx derived from respiratory diverticulum
thyroid cartilage
large, V-shaped cartilage
surrounds anterior part of larynx
suspended from inferior border of hyoid bone via thyrohoid membrane
laminae meet in anterior midline as laryngeal prominence (adam’s apple)
laryngeal prominence
where laminae of thyroid cartilage meet in midline
makes adam’s apple
cricoid cartilage
only complete ring of cartilage that surrounds the airway
narrow anteriorly and wide posteriorly
articulates with inferior horns of thyroid cartilage
epiglottis
leaf-shaped cartilage attached to body of hyoid bone and internal surface of thyroid cartilage
forms anterior border of laryngeal inlet
moves inferiorly during swallowing to cover laryngeal inlet
arytenoid cartilage
two small cartilages that resemble pair of boots
resting on upper border of cricoid cartilage
have vocal process that projects anteriorly - vocal ligament attaches here
muscular process projects laterally
highly mobile - can slide, rotate and tilt on superoir surface of cricoid
affects position of vocal ligaments
aryepiglottic folds
round bulges contain pairs of supportive cartilages = corniculate and cuneiform
corinculate more medial - rests on top of arytenoid cartilage
thyrohyoid membrane
wide membrane that connects upper margin of the thyroid cartilage to the hyoid bone
small hole on each side that transmits superior laryngeal vessels and internal laryngeal nerve
quadrangular membrane
extends from epiglottis to arytenoid cartilage
forms aryepiglottic fold and lateral wall of entrance to larynx
lower free boarder = vestibular ligament
aryepiglottic fold
formed by quadrangular membrane
vestibular ligament
false vocal cord
formed from lower free border of quadrangular membrane
within vestibular fold
vestibular fold
vestibular ligament plus mucous membrane covering it
conus elasticus/cricothyroid ligament
connects superior surface of cricoid cartilage to the vocal process of arytenoid cartilage and internal midline of the thyroid cartilage
superior free end is thickened, forms true vocal ligament
vocal ligament
formed by thickened superior free end of conus elasticus
median cricothyroid ligament
mid-portion of conus elasticus
incised during a cricothyrotomy
hyoepiglottic ligament
anchors epiglottis to hyoid bone
thyroepiglottic ligament
anchors epiglottis to thyroid cartilage
interior of larynx
covered by mucous membrane derived from endoderm
most ciliated pseudostratified columnar
laryngeal inlet
opening into the larynx from laryngopharynx
boundaries = epiglottis, aryepiglottic folds laterally, interarytenoid notch posteriorly
vocal folds
contain true vocal ligament covered by mucous membrane plus vocalis muscles
ventricles
lateral recesses between the vestibular folds and vocal folds
each has saccule
saccule
anterior projection from ventricle
contains mucous glands that lubricate vocal folds
vestibule
area between inlet and vestibular folds
glottis
space between vocal cords
infraglottic cavity
space inferior to the vocal cords and superior to the trachea
sensory innervation to interior of larynx
to area superior to vocal folds: internal branch of superior laryngeal nerve
to vocal folds and area inferior to the vocal folds: recurrent laryngeal nerve
position of vocal cords during different states?
during quiet respiration: vocal cords partially abducted (glottis open)
during forced inspiration: complete adduction of vocal cords (glottis opens fully)
phonation: adducted - sound produced when air from lungs forced up through folds
effort closure and swallowing: closure of glottis, laryngeal inlet narrows
extrinsic muscles of larynx
muscles that move larynx as a whole
usually by moving hyoid bone
elevate: suprahyoid: geniohyoid; mylohoid; digastrics; stylohyoid
depress: infrahyoid: sternohyoid; omohyoid; sternothyroid; thyrohyoid
intrinsic muscles of larynx
act of specific part of larynx alter length or tension of vocal folds of change size or shape of glottis derived from 4th-6th arches - cricothyroid - thyroarytenoid - vocalis - posterior cricoarytenoid - lateral cricoarytenoid - transverse arytenoid - oblique arytenoid all innervated by recurrent laryngeal nerve except cricothyroid (external branch of superior laryngeal nerve)
cricothyroid
extends between cricoid and thyroid cartilages
pulls anterior part of thyroid cartilage inferiorly, stretching the vocal folds and increasing tension on them
innervated by external branch of superior laryngeal nerve (vagus)
only intrinsic muscle of larynx not innervated by recurrent laryngeal nerve
thyroarytenoid
from internal aspect of thyroid cartilage
inserts on lateral border of arytenoid cartilage
sphincter of vestibule
innervated by recurrent laryngeal nerve
vocalis
between arytenoid cartilage and internal aspect of thyroid cartilage
medial portion attaches to vocal ligament
adjusts tension of vocal fold
innervated by recurrent laryngeal nerve
posterior cricoarytenoid
from posterior surface of cricoid cartilage
passes upward and laterally
inserts on muscular process of arytenoid cartilage
innervated by recurrent laryngeal nerve
action opposes that of lateral cricoarytenoid
pulls muscular process of arytenoid toward midline
causes vocal process of arytenoid to move laterally => vocal ligaments move apart => abduction of vocal fold
innervated by recurrent laryngeal nerve
lateral cricoarytenoid
from superior surfface of cricoid cartilage
passes up and backward
inserts on muscular process of arytenoid cartilage
innervated by recurrent laryngeal nerve
action opposes that of posterior cricoarytenoid
pulls muscular process of arytenoid cartilage laterally => vocal processes move medially => adduction of vocal fold
transverse arytenoid
extends between the two arytenoid cartilages
fibers oriented in transverse fashion
moves arytenoid cartilages closer together => closing posterior portion of glottis
innervated by recurrent laryngeal nerve
oblique arytenoid
muscle fibers extend from one arytenoid to the other, but fibers oriented in oblique fashion
some continue upward in aryepiglottic fold = aryepiglottic muscle
act as sphincters => reduce size of laryngeal inlet
innervated by recurrent laryngeal nerve
aryepiglottic muscle
upward extension of fibers from oblique arytenoid
acts as sphincter => reduces size of inlet
innervated by recurrent laryngeal nerve
course of recurrent laryngeal nerve in thorax
enters thorax and loops around aortic arch
if patient presents with hoarse voice, must consider pathology of thorax
blood supply to larynx
from superior and inferior laryngeal arteries
branches of superior and inferior thyroid arteries
superior laryngeal artery
branch of superior thyroid artery from ECA
travels through hole in thyrohyoid membrane with internal laryngeal nerve
blood supply to larynx
inferior laryngeal artery
branch of inferior thyroid artery = branch of thyrocervical trunk
ascends along trachea with recurrent laryngeal nerve
enters larynx at inferior border of inferior pharyngeal constrictor muscle
