Anatomy of the larynx Flashcards
What is the difference between the larynx and laryngopharynx
Larynx for air
Laryngopharynx for food
What are the functions of the larynx?
- Airways protection - prevents food/ fluid entering main function!
- Ventilation - movement of air in/out of lungs
- Role in cough reflex
- Role in phonation
Describe the anatomy of the larynx
- Suspended from and lies below the hyoid bone
- Begins at the laryngeal inlet
- Ends at lower border of cricoid cartilage C6
- Continues as the trachea
Identify the features of the larynx
Identify the cartilage of the larynx
What is significant about the cricoid cartilage?
It is the only complete ring of cartilage in the respiratory tract
Identify the cartilage and membranes of the larynx
Explain what a cricothyroidotomy is
- A way of providing emergency access to the airways beneath the vocal vords
- Used on the rare occasion a patients cannot be intubated or ventilated
- Incision made in the cricothyroid membrane
Identify the features that make up the laryngeal inlet
Identify the borders that form the true and false vocal crods
What is the largnygral ventricle and saccule and what is the function of these?
Ventricle = A small recess between the vestibular and vocal cords
Leads laterally and upwards to the saccule that contains mucous glands to keep the true vocal golds moist
What is the Rima glottidis?
The space between the true vocal cords
What type of epithelium lines the larynx? What is the exception
Pseudostratified ciliated columnar epithelium
EXCEPT the true vocal cords which are stratified squamous
How can you view the vocal cords?
- Endotracheal tube into subglottic region for intubation
- Flexible nasoendoscopy, tube inserted by the nasal cavity
What are the 2 broad actions of the intrinsic laryngeal muscles?
- Alter size and shape of the laryngeal inlet
- Alter the tension/ position of the vocal cords
Explain what happens to the vocal cords during swallowing
- Intrisic laryngeal muscles cause:
- Vocal cords adduct
- Laryngeal inlet closes
- Protects respiratory tract
Explain what happens to the vocal cords during inspiration and expiration?
- Intrinsic laryngeal muscles cause:
- Vocal cords to open (adbuct)
- Laryngeal inlet opens
- Air can move through
What happens to the vocal cords during the cough reflex?
- Inspire and fill the lungs with air
- Initally vocal cords close
- Expiratory muscles contract
- Build up of intra throracic pressure
- Vocal cords then abduct to expel the cough
What is the only muscle that can abduct the vocal cords and is therefore the most important muscle in the body!
Posterior Cricoarytenoid
What determines the size/ apeture of the rima glottidis/ glottis?
The postion of the arytenoids on the cricoid determines the postion of the true vocal cords
What is the nerve supply to the intrinsic muscles of the larynx?
All muscles supplied by the recurrent laryngeal nerve (branch of Vagus X)
EXCEPT cricothyroid muscle which is supplied by external branch of superior laryngeal nerve
Explain what happens to the vocal cords during phonation
- Vocal cords closely adduct
- Expired air forced through the closely adducted vocal cords
- vocal cords vibrate and produce sound waves
Explain how the pitch of sound is affected by the vocal cords
High pitched sounds → vocal cords are taut
Low pitched sounds → vocal cords are less taut
Which muscle increases the tension of the vocal cords? Explain how
Cricothyroid muscle
Tilts the thyroid cartilage forward on cricoid cartilage
What happens in the larynx during swallowing
- Hyoid bone elevates and moves anteriorally by the action of suprahyoid muscles
- Larynx moves up and forward
- Tongue pushes epiglottis posteriorly and aryepiglottic muscles contract
- Narrows the laryngeal inlet
- Vocal cords adduct
Which nerve supplies sensory information from the supraglottis and glottis?
Internal superior laryngeal
Which nerve supplies sensory information from the infraglottis (below the vocal cords)?
Recurrent laryngeal nerve
What kind of things can cause vocal cord palsy?
- Damage to recurrent laryngel nerve in thryroid surgery due to close relationship with inferior thyroid artery
- Aortic arch aneurysm (damages left RLN)
- Cancer of the apex of the lung
- Disease or surgery of the larynx, oesopagus or thyroid
What are the effects of unilateral recurrent larygneal nerve palsies?
- Hoarse Voice
- Ineffective cough reflex
Why are bilateral vocal cord palsies so dangerous?
- Vocal cords are paralysed and in a paramedian position
- Naroow glottis
- Significant airway obstruction
- Needs emergency surgery to the airway
What are some of the conditions that affect the vocal cords?
- Laryngitis (inflammation)
- Laryngeal nodules
- Laryngeal cancer
- Croup
- Epiglottitis
- Laryngeal oedema e.g. allergic reaction
How would a patient with a compromised upper airway due to swelling of the larynx, present?
- Stridor
- Raised resp rate
- Distress
- Hypoxia
- +/- cyanosis
