Download larynx

Muscle
Group
Muscle
Sphincteric
Innervation
Action
Recurrent
Laryngeal (CN X
+ fibers from XI)
Close off larynx
during
swallowing
Relaxes vocal
fold
Thyroarytenoideus
Aryepiglotticus
Thyroepiglotticus
Interarytenoideus
(oblique fibers)
Adjustors of
larynx and
vocal cords
Attachments/
comments
O: one arytenoid
cartilage
I: opposite arytenoid
cart.
Ensure that the
arytenoid
cartilages are
brought together
at the same time
as the epiglottis
is pulled
inferiorly toward
these cartilages
Widens inlet of
larynx
O: arytenoid cart.
I: aryepiglottic fold
* continuation from
oblique interarytenoideus
Closes inlet of
larynx
O: one arytenoid cart.
I: opposite arytenoid
cart.
* two bundles that
cross each other
O: internal surface of
thyroid cart.
I: laterally on
epiglottic cart.
Open and close
the rima glottidis
(space b/t vocal
folds)
Lateral
cricoarytenoideus
Recurrent
laryngeal
(CN X + fibers
from CN XI))
Pull muscular
processes
anteriorly,
rotating
arytenoids so
that their vocal
processes swing
medially 
vocal fold
adduction 
(closure of rima
glottidis)
O: arch of cricoid
cart.
I: muscular process
of arytenoid cart.
Posterior
cricoarytenoideus
Rotate arytenoid
carts.  lateral
deviation 
abduction of
vocal folds 
(widening of
rima glottidis)
Adducts vocal
folds, and closes
inlet of larynx
Interarytenoideus
(transverse fibers)
Vocalis
Cricothyroideus
External
laryngeal n. (CN
X + fibers from
XI)
Pulls arytenoid
cartilage
anteriorly 
relaxation of
vocal folds
Pull thyroid cart.
anteriorly on the
cricoid cart 
increased
distance b/t
thyroid and
arytenoid carts.
tensing of
vocal folds
(elongation/tight
ening of vocal
ligaments
O: posterior surface
of lamina of cricoid
cart.
I: muscular process
of arytenoid cart.
O: one arytenoid
cartilage
I: opposite arytenoid
cart.
* only unpaired muscle of
the larynx
O: Angle b/t lamina
of thyroid cart.
I: Vocal process of
arytenoid
O: anterolateral
cricoid cart.
I: Inf. horn of thyroid
cart.
Skeleton

Hyaline cartilages
1. Thyroid
- l/r laminae
- superior cornu (horn)
- inferior cornu (horn)  articulates w/ cricoid @ cricothyroid joint (synovial
hinge)
2. Cricoid:
- complete ring (anterior arch + posterior lamina)
3. Arytenoids
- paired
- muscular process – projects laterally, attaches to lateral and posterior
cricoarytenoid muscles
- vocal process – projects forward, attaches to vocal ligament and vocalis muscle
4. & 5. Corniculate & Cuneiform


- not important
- on top of arytenoid cartilages
Elastic cartilage
1. Epiglottic – attached to posterior surface of thyroid cart. by thyroepiglottic
ligament
Membranes
1. Thyrohyoid
- contains foramen for superior laryngeal n. (branch of CN X) & superior
laryngeal artery
- connects larynx to hyoid
2. Cricotracheal ligament
- connects larynx to trachea
3. Cricothyroid ligament
- connects cricoid cart. to thyroid cart.
4. Intrinsic membranes: fibroelastic
(a) Quadrangular/aryepiglottic membrane
- connects epiglottic and arytenoid cartilages
- upper free border covered by mucous membrane = aryepiglottic fold (@
entrance to larynx)
- lower free margin covered by mucous membrane = vestibular ligament (false
vocal cord)
(b) Triangular/cricothyroid membrane
- lateral to cricothyroid ligament, runs interiorly from cricoid cart.
- connects cricoid, thyroid, and arytenoid cartilages (@ vocal processes)
- upper free border: vocal ligament (true vocal cord)
- forms lateral edge of rima glottidis
- lower free border: cricoid cartilage
- right + left  form conus elasticus (looks like triangle from a posterior
view)
Interior Larynx:





entrance = aditus
cavity: superior to inferior
aditus  vestibule  vestibular folds  ventricle  vocal folds infraglottic cavity
 lower cricoid border
rima vestibuli: opening b/t vestibular folds
rima glottidis: opening b/t vocal folds
glottis: rima glottidis + vocal folds
Innervation:
CN X – motor, sensory and parasympathetic
Branches:
1. Superior Laryngeal Nerve – divides w/in carotid sheath into two terminal
branches:
(a) External laryngeal nerve:
- motor to cricothyroideus
- pierces inferior constrictor muscle of pharynx
(b) Internal laryngeal nerve:
- sensory and preganglionic parasympathetic supply to mucosal lining
of larynx to level of vocal cords
- pieces thyrohyoid membrane w/ superior laryngeal artery
2. Recurrent Laryngeal Nerve:
- motor to all intrinsic laryngeal muscles (except cricothyroideus)
- sensory and preganglionic parasympathetic supply to mucosal lining of larynx
below vocal cords
- ascends in groove b/t trachea and esophagus giving branches to pharynx,
esophagus, and trachea
- terminal part: inferior laryngeal nerve
- damage  reduces voice to whisper
Functions:
1. Sphincter: swallowing, coughing, abdominal straining
2. Phonation:
Vibration of vocal folds: anterior vibrations  high pitch
Primary muscles: cricothyroid and vocalis
Random stuff:
Vocal fold = vocal ligament, conus elasticus, muscle fibers, + mucous membrane
A cute little way to remember innervation of larynx and pharynx:
both end w/ x, x = X, X = vagus
Muscles which move larynx as a whole:
Infrahyoid muscles (omohyoid, sternohyoid, sternothyroid) – depressors
Suprahyoid muscles (stylohyoid, digastric, mylohyoid, geniohyoid,) +
stylopharyngeus  elevate hyoid bone and larynx
Cricothyrotomy: incision made through skin and cricothyroid ligament for relief of
respiratory obstruction
Tracheotomy – insertion of metal tube into the trachea
Laryngectomy: removal of larynx
- esophageal speech possible (regurgitating ingested air)
Puberty: walls of larynx strengthen, laryngeal cavity enlarges, vocal folds lengthen and
thicken (particularly in males), laryngeal prominence becomes conspicuous in males
Swallowing (you might want to read this section along w/ the notes on the pharynx):
Two stages:
A. Voluntary:
CN V –
1. sense food in oral cavity
2. grind food w/ muscles of mastication
3. elevate floor of oral cavity w/ mylohyoid
CN VII – push food b/t teeth by buccinator muscle
CN XII – tongue shaped for swallowing, pushes food past
palatoglossus arches
B. Involuntary
Nasopharynx closed off:
CN V – soft palate tenses from tensor palatini muscle
CN X –
Soft palate elevates from levator palatini muscle
Contraction of palatopharyngeus and upper fibers of
superior constrictor muscles
CN X: Larynx and pharynx elevated: stylopharyngeus,
salpingopharyngeus, palatopharyngeus, and
thyrohyoid muscles
Peristaltic-like contraction of constrictors moves food to
laryngopharynx
Aditus of larynx constricted by contraction of oblique
arytenoid muscles and thyroarytenoid muscles
Epiglottis covers aditus
Food passes to either side through epiglottic valleculae
Lasts about 2 sec.