Session 10 - Larynx Flashcards
What is the larynx? Where is it?
‘Voice box’
Tube created by ligaments, membranes, cartilage and muscle.
Lies below the hyoid bond.
Is the inlet for air into the lower respiratory tract?
What is the upper/ lower respiratory tract?
Upper is all parts of the tract above the larynx.
Lower is parts below larynx (trachea, bronchi, bronchioles etc)
What are the functions of the larnyx?
- Protects the airway (closes on swallowing)
- Phonation - speech and sound.
- Allows forced cough reflex to clear trachea.
Where would you cut for emergency airway access, what is it called?
Cricothyroidotomy
- Entrance via cricothyroid membrane (below vocal cords).
- below thyroid cartilage, above cricoid.
(when patient cannot be intubated or ventilated, in emergency)
What is the vestibular ligament?
Free lower border of the quadrangular membrane. (false vocal cord)
What is the vocal ligament?
Upper free border of cricothyroid ligament - thickened edge forming vocal ligament.
What is the position of the larynx in relation to the laryngopharynx?
Larynx lies anterior to laryngopharynx.
What are the saccules of the larynx?
Small recess (ventricle) between the vestibular and vocal folds which leads laterally and upwards into saccule, contains mucus glands to keep vocal cords moist.
What sections is the laryx split into?
- Supraglottis: Laryngeal vestibule (opening) (epiglottis> false vocal cords)
- Glottis: True vocal cords
- Infraglottis
What type of epithelium lines the larynx?
Pseudostratified ciliated columnar epithelium.
What type of epithelium covers the vocal cords? Why?
Stratified squamous epithelium.
Lots of movement/ abrasion so ensures protection.
How is intubation performed?
- Patients neck extended.
- Laryngoscope used (to epiglottis) - tongue pulled forward.
- endotrachial tube inserted, and balloon inflated to create a seal.
What is important about the balloon on the endotrachial tube?
- Airtight, so ventilation is effective.
- Prevents oesophageal contents entering trachea where they can cause injury.
What is nasendoscopy?
- Endoscope through the nose (floor of nasal cavity)
- Visualises the larynx/ structures.
What do the muscles of the larynx do (function)?
- Change size and shape of inlet
- Move position to alter tension of vocal folds (cords)
Close larynx - swallowing
open larynx - breathing
Control movements in phonation and cough reflex.
Which muscles is responsible for opening the vocal folds?
Posterior Cricoarytenoid
What are the arytenoid cartilages?
Pair of cartilages in posterior larynx (on cricoid cartilage).
Intrinsic muscles determine opening of aperture of glottis (thus sound)
Which nerve supplies the intrinsic muscles of the larynx?
Inferior laryngeal nerve (branch of recurrent laryngeal nerve (from vagus)).
Apart from Cricothyroid which is external branch of superior laryngeal nerve. (external laryngeal nerve)
What is the role of the cricothyroid muscle? Which nerve innervates it?
Tilts the thyroid cartilage forward, increasing vocal cord tension.
This increases pitch.
External Laryngeal nerve (external branch of superior laryngeal nerve)
Which muscles act to close the glottis during swallowing?
Contraction of aryepiglottic muscles (narrow inlet, pull down epiglottis)
Suprahyoid and Pharyngeal muscles elevate larynx.
Closure of vocal cords (glottis)
What is the function of the superior laryngeal nerve, which structures does it innervate?
Is a branch of vagus nerve.
Gives rise to INTERNAL and EXTERNAL branch.
Internal = sensory.
External = motor to cricothyroid.
What is the importance of the relationship between the thyroid artery and external larygneal nerve?
Run very closely together.
Can be damaged in thyroid surgery (e.g. removal)
Leaves vocal cord/s in abducted position (can’t adduct) so gives an aspiration risk.
What is the route of the recurrent laryngeal nerve? Which structures does it innervate?
Arises distally looping under right subclavian artery (left) and under aorta (on right).
Ascends in tracheo-oesophageal groove.
Innervates ALL intrinsic muscles of Larynx!
Sensory BELOW vocal cords.
What can cause a unilateral vocal cord palsie?
Damage to Recurrent laryngeal nerve.
- Aortic arch aneurism (left)
- Cancer in apex of lung (right)
- Disease/ surgery involving larynx/ oesophagus or thyroid.
Innervates intrinsic muscles which move vocal cords, which is why there is a palsy.
What signs of a unilateral vocal cord palsy would there be?
- Paralysed side = vocal cord neither abducted or adducted.
- Hoarseness of voice
- Ineffective cough (can’t close glottis tightly)
(often normal side can compensate by moving more over slightly)
What happens in a bilateral vocal cord palsie?
Both paralysed, so glottis cannot open properly due to paralysed intrinsic muscles.
- NARROW glottis!
This is significant airway obstruction. Needs emergency surgical airway for survival.
What may be some signs of a bilateral vocal cord palsie?
- Stridor (high pitched wheezing noise) - turbulent airflow.
- Possible cyanosis
etc
