Anatomy Of Larynx Flashcards
What does the larynx lie below?
The hyoid bone
What does the larynx begin as?
Laryngeal inlet
What does the larynx continue as?
The trachea (at C6/ lower boarder of cricoid cartilage)
What is the route of inspired air?
Oral cavity/ nasopharynx -> oropharynx -> larynx -> trachea
What route does food take to get to stomach?
Oral cavity-> oropharynx -> laryngopharynx -> oesophagus
What is the main function of the larynx?
Provide a protective sphincter for the lower respiratory tract
What 3 SINGLE cartilages make up the larynx?
Thyroid
Cricoid
Epiglottis
What 3 PAIRED cartilages contribute to the larynx?
Arytenoid cartilages
Corniculate
Cuneiform
Numerous membranes and ligaments help give shape to the larynx e.g :
Thyrohyoid membrane
Cricothyroid ligament
Cricotracheal membrane
Quadrangular membrane
What is the only complete ring of cartilage in respiratory tract?
Cricoid cartilage
What shape is the cricoid cartilage described as?
Signet ring
What does the epiglottis attach to?
The inner surface of thyroid cartilage via series of ligaments
What type of joint is between the cricoid and thyroid cartilage?
Synovial
What is the Adam’s apple?
Laryngeal prominence of thyroid cartilage
When is a cricothyroidectomy needed?
When a patient cannot be intubated or ventilated e.g swelling to vocal cords
Emergency access to provide patent airway - the cricothyroid membrane is below the vocal cords
What is the quadrangular membrane?
Membrane that joins edges of epiglottis to arytenoid cartilage and inner surface of thyroid cartilage.
Forms an oval shape opening into larynx - margins of this oval =aryepiglottic folds
What lies at side of laryngeal inlet?
Pisiform fossa
What is the vestibular ligament?
The free lower boarder of the quadrangular membrane
What is the vestibular ligament also called?
False vocal cord
What is the vocal ligament?
Thickening of the upper boarder of the cricothyroid ligament
What is another name for the vocal ligament?
True vocal cord
What type of epithelium lines the larynx?
Pseudostratified ciliated columnar epithelium
EXCEPTION = true vocal cords = stratified squamous epithelium
The larynx is divided into 3 regions…
Supraglottis (or laryngeal vestibule)
Glottis
Infraglottis
The supraglottis lies above the…
Vocal cords
= from the epiglottis to false vocal cords
What is the glottis?
True vocal cords and gap between them
What is the infraglottis?
Below the vocal cords, ending at inferior border of cricoid
Why does the true vocal cord have stratified squamous epithelium?
This epithelium found in areas under abrasive forces - lots of air vibrating through true vocal cords
What lies between vestibular and vocal folds?
The saccule - contains mucus glands that keep folds moist
What is the rima glottidis?
Gap between true cords
There are many laryngeal muscles, what are their main actions?
Close larynx during swallowing to protect respiratory tract
Open larynx to allow movement of air
Control movements of vocal cords in phonation and cough reflex
What is the role of posterior cricoarytenoid?
Abduct (open) vocal cords
The only muscle capable of widening the rima glottidis
What determines the position of the true vocal cords and therefore size of the aperture?
Position of arytenoids on cricoid cartilage
What supply all the intrinsic laryngeal muscles? (Except cricothyroid muscle)
Recurrent laryngeal nerve of vagus CN X
What supplies the cricothyroid muscle?
External branch of the superior laryngeal nerve - branch of vagus nerve
During inspiration and expiration, what do the vocal cords do?
Abduct
What do the vocal cords do during phonation?
Adduct - expired air forced through closely adducted cords to vibrate a column of air
What happens to cords during a cough?
Vocal cords powerfully adduct, intrathoracic pressure builds, then cords suddenly abduct
What is pitch of sound determined by?
Vocal cord tension
Are vocal cords taut or relaxed for high pitched sounds?
Taut
Low pitched - cords relaxed
What does bilateral contraction of cricothyroid muscles do?
Increased length and tension in vocal cords
- does this by tilting thyroid cartilage forward on cricoid
What artery the external laryngeal nerve closely related to?
Superior thyroid
Injury to the external branch of superior laryngeal nerve can lead to…
Hoarseness of voice - especially high pitch sounds
What are the extrinsic muscles of the larynx?
Suprahyoid: geniohyoid, mylohyoid, digastric, stylohyoid
Infrahyoid: thyrohyoid, sternothyroid, omohyoid, sternohyoid
What is the role of the supra and infrahyoid muscles?
Suprahyoids - elevate larynx
Infrahyoids - depress larynx
What happens to the larynx during swallowing?
Contraction of ariepiglottic muscles to narrow laryngeal inlet and pull down epiglottis
Elevation of larynx (pharyngeal muscles and suprahyoid muscles)
Closure of vocal cords
The superior laryngeal nerve gives rise to internal and external branches. What do the do?
Internal - purely sensory (above vocal cords)
External - motor to cricothyroid
The vagus nerve loops under what … to form recurrent laryngeal nerve?
On the left - arch of the aorta
On right - subclavian artery
Ascends in tracheo-oesophageal grove
What does the recurrent laryngeal nerve innervate?
All intrinsic muscles of larynx expect cricothyroid
Sensory below vocal cords (infraglottic region)
The recurrent laryngeal nerve is closely associated with what artery?
Inferior thyroid artery
What situations can put the recurrent laryngeal nerve at risk?
Thyroid surgery - RLN is close to inferior thyroid artery
Aortic arch aneurysm (left RLN)
Cancer involving apex of lung (right RLN)
Disease or surgery involving larynx, oesophagus or thyroid
Unilateral RLN lesions can cause…
Unilateral vocal cord palsies
What symptoms can a unilateral vocal cord palsy cause?
Hoarseness of voice
Ineffective cough
A paralysed vocal cord assumes what position?
Paramedian - between fully abducted and full adducted
What happens in bilateral RLN lesion?
Both vocal cords paralysed and in paramedian position
Narrow glottis
- significant airway obstruction- emergency surgical airway
