functional anatomy of larynx Flashcards
function of larynx
phonation
swallowing
breathing
the larynx serves to
- guard air passages during swallowing
- maintain a patient airway
- vocalization
relations of the larynx
- anterior: superficial
- lateral: related to carotid sheath, infrahyoid muscles, sternomastoid, and the thyroid gland
- posterior: related to laryngopharynx, prevertebral fascia and muscles, and to bodies of cervical vertebrae 3-6
C6 is the start of?
cricoid cartilage (lower end of pharynx and upper of esophagus)
3 single cartilages of larynx
- epiglottis
- thyroid
- cricoid
3 paired cartilages of larynx
- arytenoid
- corniculate
- cuniform
what are the ligaments that connect the cartilages of the larynx?
thyrohyoid, cricothyroid, aryepiglottic, vocal, and vestibular
muscle attachments of oblique line
- thyrohyoid muscle
- sternothyroid muscle
- inferior constrictor muscle
posterior border of thyroid cartilage muscle attachments
- stylopharyngeus
- palatopharyngeus
- salpingopharyngeus
cricoid cartilage
- signet ring shape
- posterior plate= lamina
- anterior=arch
- lamina articulates with arytenoid cartilages
- level of C6
- end of pharynx and larynx –> start of esophagus and trachea
epiglottic cartilage
leaf shaped cartilage covered by mucous membrane to form epiglottis
where is the epiglottis?
posterior to root of tongue and body of hyoid bone and anterior to the inlet of larynx
-inferior end is anchored to posterior of thyroid cartilage
where are taste buds on the epiglottis?
posterior surface
arytenoid cartilages
- articulate with superior border of cricoid
- each has superiorly-positioned apex and base that comprises inferior part
- base–> vocal process anteriorward and lateral –> muscles
all intrinsic muscles except for — are attached to arytenoid cartilage
all intrinsic muscles except for cricothyroid
the —— and —– cartilages are nodules in the aryepiglottic folds
corniculate and (inconstant) cuneiform
thyrohyoid membrane
- connects the thyroid cartilage with the hyoid bone
- median part is thickened to form a ligament
- membrane is pierced on each side by the internal laryngeal nerve and superior laryngeal vessels
cricothyroid ligment
- connects the arch of the cricoid cartilage with the thyroid cartilage
- acute resp obstruction–> cricothyrotomy by penetrating cricothyroid membrane
conus elasticus
elastic fibers that extend from cricoid cartilage to the vocal ligaments
vocal ligament
- extends the thyroid cartilage to arytenoid cartilage
- “vocal cord” = upper border of conus elasticus
- composed of elastic fibers covered tightly by a vocal fold of mucous membrane
- formed by vocalist muscle (part of the thyro-arytenoid muscle)
glottis
vocal folds and processes with interval (rima glottidis) between them
rima glottidis
narrowest part of laryngeal cavity
vestibular ligament
superior to the vocal ligament and covered loosely by the vestibular fold (false vocal cord)
what is the epiglottis attached to?
attached by ligaments to the hyoid bone, to the posterior aspect of the tongue, to the sides of the pharynx, and to the thyroid cartilage
the larynx as a whole can be elevated and depressed by ?
extrinsic muscles
what muscles depress the larynx during swallowing?
infrahyoid muscles
what muscles are inserted in the posterior border of thyroid cartilage and elevate the larynx during swallowing?
- stylopharyngeus
- palatopharyngeus
- salpingopharyngeus
what are the intrinsic muscles of the larynx?
- sphincters of inlet
- muscles that close and open the rima glottidis
- muscles that regulate the vocal ligaments
sphincters of the inlet
- transverse arytenoid
- oblique arytenoid
- aryepiglottic
muscles that close and open the rima glottidis
- lateral cricoarytenoid (adductor)
- posterior cricoarytenoid (abductor)
muscles that regulate the vocal ligaments
- thyroartenoid
- vocalis
- cricothyroid
**whats the only abductor in the airway?
posterior cricoarytenoid (keeps the airway open)
all muscles of larynx are supplied by the —– except the —-
recurrent laryngeal except cricothyroid which is supplied by external laryngeal
what muscles adduct the vocal cords?
-lateral cricoarytenoid
-oblique and transverse arytenoid muscles
(close the glottis–phonation)
after closure of the glottis, the vocal folds can be tightened and lengthened by —- to change the pitch and tone of voice
cricothyroid muscles
how does the inlet close and why?
- protects the respiratory passages against food and foreign bodies
- contraction of aryepiglottic and transverse arytenoid muscles and posterior motion of the epiglottis that is produced by the elevation of the larynx
laryngeal inlet
- passage from laryngopharynx into cavity of the larynx
- bounded anteriorly by superior border of epiglottis, aryepiglottic folds, and inferiorly and posteriorly by an interarytenoid fold
- related laterally to the piriform recesses of laryngopharynx
3 portions of the laryngeal cavity
- vestibule
- ventricles
- rima glottides
- infraglottic cavity
vestibule of cavity
extends from inlet to vestibular folds
ventricles of cavity
extends laterally in interval bw vestibular and vocal folds
anterior 3/5 of glottis
intermembranous portion between the vocal cords
posterior 2/5 of glottis
intercartilaginous portion
bw vocal process of arytenoid cartilages
infraglottic cavity
extends from rima glottidis to trachea
3 layers to close larynx
- closure of inlet–during deglutition to protect resp passages against invasion of food
- closure of vestibular folds–traps air in trachea and makes possible an increase of intrathoracic pressure or intra-abdominal pressure
- closure of vocal folds–during phonation
whats the most common cause of laryngeal spasm?
presence of a foreign body
extrinsic muscles’ job during phonation
pull up (high tones) and pull down (low tones) the larynx
intrinsic muscles’ job during phonation
- adduction of the chords (lateral cricoarytenoid, transverse arytenoid, vocalist)
- variation of length and tenseness of chords (cricothyroid and thyroarytenoid change tone of voice)
- abduction of chords: posterior cricoarytenoid
sensory and motor innervation of larynx
vagus – superior laryngeal and recurrent laryngeal
superior laryngeal nerves
- external branch–descends along lateral wall of pharynx to supply the inferior constrictor of the pharynx and cricothyroid muscle
- internal branch–penetrates the thyrohyoid membrane. Mainly sensory to laryngeal mucosa superior to level of vocal folds
recurrent laryngeal nerves
sensory: laryngeal mucosa below level of vocal folds
motor: to all intrinsic muscles of larynx except for cricothyroid
origin of each recurrent laryngeal nerve
- left–from thorax (left=longer)
- right–root of neck
both ascend in neck in groove between esophagus and trachea and enter the larynx deep to the margin of the inferior constrictor
superior laryngeal artery
- origin: near the upper margin of thyroid cart from superior thyroid branch of external carotid
- goes with internal branch of superior laryngeal nerve thru thyrohyoid membrane to reach the larynx
inferior laryngeal artery
- origin: inferior thyroid branch of thyrocervical trunk of subclavian artery low in neck
- goes with recurrent laryngeal between esophagus and trachea
- enters larynx by passing deep to margin of inferior constrictor muscle of pharyx
veins draining larynx
- superior laryngeal vein–> superior thyroid vein–> internal jugular
- inferior laryngeal vein–> inferior thyroid veins–> left brachiocephalic vein
superior group of lymphatics
- prelaryngeal nodes
- upper portion of deep cervical chain
inferior group of lymph
- below vocal cord
- pre and paratracheal nodes
- lower deep cervical nodes
- supraclavicular nodes
where does thoracic duct end?
receives from below diaphragm and ends between internal jug vein and subclavian vein
protective mechanisms against choking
- breathing stops during swallowing
- reflex glottic closure
- larynx pulled upwards against epiglottis
- epiglottis becomes more horizontal
- upper laryngeal opening is oriented sideways
- coughing and gag reflexes when food or liquid goes out of way
unilateral paralysis of superior laryngeal nerve
- paralysis of cricothyroid, ipsilateral anaesthesia of larynx above vocal cord
- causes: * thyroid surgery, tumors, diphtheria
- symps: weak voice, anaesthesia of larynx one one side, aspiration
bilateral paralysis of superior laryngeal nerve
- uncommon
- both cricothyroid are paralyzed with anaesthesia of upper larynx
- causes: surgery or trauma, diphtheria, cervical lymphadenopathy, neoplastic disease
- symps: VC paralysis, anaesthesia of larynx, cough, choking fits, weak voice
unilateral recurrent laryngeal paralysis
- ipsilateral paralysis of all intrinsic muscles of larynx except cricothyroid
- vocal cords–medial position and doesn’t move laterally
- symps: aysmptomatoc, change in voice
- tx: none
**bilateral recurrent laryngeal paralysis
- position of vocal cords: all intrinsic muscles of larynx are paralyzed, VC lie in median position due to unopposed action of cricothyroid muscles
- symps: dyspnoea, stridor (can’t breathe)
- cause: usually after thyroidectomy
- tx: traciostomy, cordotomy, arytenoidectomy
incomplete paralysis refers to
RLN paralysis
complete paralysis refers to
external and recurrent laryngeal nerve paralysis
