Larynx Flashcards
What are the functions of the larynx?
Airway protection - prevents food / fluid ect.. entering airways
Ventilation - movement of air into / out of the lungs
Cough reflex - rapidly expel everything inadvertently entering airway
Production of sound
What is the larynx?
A ‘Tube’ created by a series of ligaments / membranes, cartilage and muscles.
It lies behind the hyoid bone.
It begins at laryngeal inlet and continues as the trachea at C6 / lower border of cricoid cartilage.
What is the route of inspired air?
Oral cavity or nasopharynx
Oropharynx
Larynx
Trachea
What is the route of food?
Oral cavity
Oropharynx
Laryngopharynx
Oesophagus
What things make up the larynx?
Three single cartilages:
Thyroid, cricoid, epiglottis
Three paired cartilages:
Arytenoid, Carnicuate, Cuneiform
Numerous membranes and ligaments connecting cartilages (and to hyoid) to help give shape to larynx:
- Thyrohyoid membrane
- Criothyroid membrane
- Cricotracheal membrane
- Quadrangulat membrane
What is a cricothyroidotomy?
Cut cricothyroid membrane for emergency access to the airway,
This is used rarely when a patient cannot be intubated or ventilated.
What does the quadrangular membrane do?
Forms the aryepiglottic fold which form the margins of oval inlet of the larynx.
Free lower margin forms edge of false vocal cord (vestibular ligament).
What is the vestibular ligament?
The free lower edge of the quadrangular membrane. It makes the vestibular folds which are the false vocal cords.
What is your vocal ligament?
True vocal cords
What makes up supraglottis, glottis and infragrottis?
Supraglottis (laryngeal vestibule) - Epiglottis to false vocal cords
Glottis (narrowest part) - vocal cords
Infraglottis (or subglottis) - vocal cords to bottom cricoid cartilage / start of tracheal.
What type of epithelium lines the larynx?
Pseudostratified ciliated columnar epithelium
EXCEPT: vocal cords - squamous epithelium.
How can you view the larynx?
Endotracheal tube
Nasoendoscopy
What are the main actions of the laryngeal muscles?
Alter size and shape of inlet
Alter size / position of vocal cord
This means that they:
- Close laryngeal inlet and vocal cords during swallowing
- Open vocal cords and allow for movement of air during inspiration and expiration
- Use movement of vocal cords in phonation and in cough reflex.
What does posterior cricoarytenoid do?
Keeps vocal cord open.
It is the ONLY muscle to do this! (all others close vocal cords)
What innovates the intrinsic laryngeal muscles?
All supplied by the recurrent laryngeal nerve of the vagus.
EXCEPT cricothyroid which is supplied by an external branch of the superior laryngeal nerve.