Larynx Flashcards
3 functions of the larynx
– Transport of air
– Protective sphincter
– Phonation
where is the larynx
Lies between the levels of ~C3- C6 vertebrae
Mobile
Slightly higher in newborns and
infants
EPIGLOTTIS
Attached to the thyroid cartilage by the thyroepiglottic ligament
Attached to the hyoid bone by the hyoepiglottic ligament
what makes up the thyroid cartilage
Left and right laminae Superior and inferior horns • Superior horns attached to the hyoid • Inferior horns articulate with the cricoid cartilage Superior thyroid notch Thyroid angle laryngeal prominence (Adam’s apple) The oblique line, for muscle attachment
CRICOID CARTILAGE
Shape of a signet ring with the lamina posteriorly
Articulates with the arytenoids and the thyroid
Note the “sloping shoulder” on the lamina for arytenoid articulation
ARYTENOID CARTILAGE
Articulates with the sloping shoulders of the cricoid lamina and, superiorly, the corniculate cartilage
Vocal process
Anteriorly, for attachment of the vocal
ligament
Muscular process:
posteriorly for the attachment of posterior and lateral crico-arytenoid muscles
THYRO-HYOID MEMBRANE
Extends between the upper edges of the thyroid laminae and superior horns and the body and greater horns of the hyoid
It is thickened anteriorly and posteriorly as the median and lateral thyro-hyoid ligaments
Pierced by superior laryngeal vessels and superior laryngeal nerve (internal branch)
FIBRO-ELASTIC MEMBRANE
- Elastic connective tissue underneath the laryngeal mucous membrane stretches between laryngeal cartilages and form fibro-elastic membranes
- Fibro-elastic membranes are separated from each other by laryngeal ventricle
• Superiorly quadrangular membrane• Inferiorly conus elasticus
QUADRANGULAR MEMBRANE
Layer of submucosa
Extends between lateral aspects of the epiglottis, arytenoid and corniculate cartilages.
Edges: aryepiglottic fold, vestibular ligament (fold
what makes up the vestibular fold
the ligament and the mucous membrane
CONUS ELASTICUS
Also called cricovocal membrane
Blends anteriorly with the median cricothyroid ligament
- The median cricothyroid ligament is the site of emergency access to the airway (tracheotomy)
VOCAL CORD
- Vocal cord controls laryngeal diameter for:
− Speech
− Coughing/sneezing
− Raising the intra-abdominal pressure - Lined with stratified squamous epithelium
Muscles within and adjacent to the vocal folds narrow or widen the opening between them (rima glottis or glottidis), or alter their tension
Vestibular cord (false vocal cord)
LARYNGEAL CAVITY
- The vestibule: between the laryngeal inlet and the vestibular folds
- The laryngeal ventricle: Recess between the vestibular and vocal folds
− Leads to the saccule, which provides lubricating mucus for the vocal folds. - The infraglottic cavity: between the vocal folds and the trachea
Laryngeal inlet
bound by the aryepiglottic folds
Rima glottis
is the opening between the vocal cords and muscular processes of the arytenoid
role of the muscles in the larynx
Its position is controlled by muscles, which, in turn
– alter laryngeal diameters to allow the passage of air only
– control airflow for speech
– raise intra-abdominal pressure
Extrinsic muscles laryngeal muscles
- Suprahyoid and infrahyoid muscles
- Arrange the position of the larynx as a whole
- Facilitate closing of the laryngeal inlet
intrinsic muscles laryngeal muscles
- Extend between laryngeal cartilages
- Adjust the length or tension of the vocal ligaments
- Open and close the rimaglottis
- Control the inner dimensions of the vestibule
- Facilitate closing of the laryngeal inlet
- Elevators of pharynx
- Salpingopharyngeus
- Palatopharyngeus
- Stylopharyngeus
Elevators of larynx
- Stylohyoid
- Mylohyoid
- Geniohyoid
- Thyrohyoid
- Digastric
Depressors of larynx:
- Sternothyroid • Thyrohyoid
* Sternohyoid
INTRINSIC LARYNGEAL MUSCLES roles
- Open/close the laryngeal inlet (aryepiglottic folds)
- Open/close the rima glottis (and rima vestibuli) - arytenoid gliding and rotation
- Lengthen the vocal folds - “rocking” at cricothyroid joints
- Close the laryngeal inlet
Elevation of the larynx and pharynx by extrinsic muscles from skull to larynx and pharynx
- Salpingopharyngeus - Palatopharyngeus
- Stylopharyngeus
- Stylohyoid
Ary-epiglottic muscle acts like a “purse-string”
Superior fibers of thyro- arytenoid muscle (a.k.a. thyro-epiglottic muscle)
open the laryngeal inlet
- Descent of larynx (and pharynx) by elastic recoil
- (Hyoepiglottic ligament)
Open vocal folds or rima glottis
Posterior crico-arytenoid muscle
- the only muscle that opens the rima glottis
Close vocal folds or rima glottis
- Inferior fibres of thyro-arytenoid
- Lateral crico-arytenoid
- Transverse arytenoid
Lengthen the vocal foldsalter the tension
- The thyroid cartilage may be rocked forwards and backwards at the cricothyroid joint.
- Crico-thyroid muscles lengthen, hence increase the tension of the vocal folds
Alter the tension of vocal folds
Vocalis muscle (part of Thyro-arytenoid muscle) change the tension of the vocal ligaments - Increasing tension raises the pitch of the voice, while decreasing tension lowers it
LARYNGOSCOPY
- Vocal folds are adducted
- Air forced through vocal folds causes vibration
- Cord length and tension are altered by cricothyroid, thyro- arytenoid and vocalis muscles
- Vocal and vestibular folds are adducted
- he airway is closed by lateral crico-arytenoid and transverse arytenoid such as the Valsalva manoeuvre
SWALLOWING
During swallowing:
− Laryngeal elevation
− Closure of the laryngeal inlet by epiglottis
As the larynx descends after swallowing the epiglottis springs back by hyoepiglottic ligament
ARTERIAL SUPPLY
Superior laryngeal a. from Superior thyroid artery
Inferior laryngeal a. from Inferior thyroid artery
VENOUS DRAINAGE
Superior laryngeal v. to superior thyroid v. to jugular internal v.
Inferior laryngeal v. to inferior thyroid v. to brachiocephalic v.
what’s at risk during a tracheostomy
The inferior thyroid veins
LYMPHATIC DRAINAGE
Above vocal cord to superior deep cervical lymph nodes
Below vocal cord to Prelaryngeal, pretracheal, inferior deep cervical and supraclavicular lymph nodes
No lymphatic connection between vocal cords
NEURAL SUPPLY
The superior laryngeal nerve, a branch of vagus
– Internal branch (internal laryngeal nerve):
• Sensation of the larynx down to just above the vocal folds
• Accompanied by the superior laryngeal artery
– External branch (external laryngeal nerve):
• Supplies Cricothyroid muscle
- Vagus recurrent laryngeal nerve inferior laryngeal nerve is accompanied by the inferior laryngeal artery
- The recurrent laryngeal nerve supplies – all the intrinsic muscles of the
larynx except cricothyroid
– sensation to the vocal cords and larynx below
