Clinical Anatomy of the Larynx Flashcards
What are some roles of the nasal cavity?
Warms and dehumidifies inspired air
Removes and traps pathogens from inspired air
Sense of smell
Drains paranasal sinuses and lacrimal ducts
Where do the olfactory nerves run?
The olfactory nerves run inferiorly from the olfactory bulb, though the perforated cribiform plate of the ethmoid bone to enter the nasal cavity.
What are the 4 paranasal sinuses?
Frontal, ethmoid, sphenoid, maxillary
What are paranasal sinuses?
The paranasal sinuses are hollow spaces within the frontal, sphenoid, ethmoid and maxillary bones. They are lined by mucous membrane and all drain into the nose.
What does the upper airway consist of?
nasal cavity nostril oral cavity pharynx larynx
What does the lower airway consist of?
trachea
R&L main bronchus
R&L lungs
diaphragm
What innervates the oral cavity?
Trigeminal nerve
What is the bony skeleton of the oral cavity made up of?
Maxilla and mandible and palatine bone (hard palate)
What is the hard palate made up of?
Maxilla anteriorly and palatine bone posteriorly
What is the cause for tonsillitis?
Majority of cases (2/3) it is caused by a virus
1/3 of cases it is caused by bacteria
Where are the palatine tonsils located?
Between the palato-glossal arch (outer) and palato-pharyngeal arch (inner)
How can you tell the difference between viral and bacterial tonsillitis?
Puss like exudates present on the tonsils in bacterial tonsillitis, not in viral
What is quinsy?
If bacterial tonsillitis is undertreated, can develop puss like exudate within the palatine tonsils instead of just on top of them, won’t respond to antibitoics, only resolution is surgical intervention and can be very dangerous as cannot swallow so end up dehydrated if don’t get enough water
What is special about the nasal cavity?
It is a dual olfactory and respiratory organ
What are the parts of the nasal cavity?
Anterior septal cartilage
Posterior vomer
Superior ethmoid (perforated roof)
Laterally - 3 conchae
What are nasal conchae?
Protuberances which stick out into the bone except from the inferior conchae which is a bone on its own.
What is the function of nasal conchae?
Designed to make sir that you breathe in turbulent enough to slow down its progress and store it in the paranasal sinuses for longer so that it can dehumidify and have an increased contact with cilia and mucus.
Where is the olfactory nerve?
Runs inferiorly from the olfactory bulb through the perforated cribiform plate of the ethmoid bone to enter the nasal cavity/
What are paranasal sinuses?
Hollow spaces lined by mucous membrane and all drain into the nose
What are some functions of the paranasal sinuses?
Maximise area of inspired air for greater pathogen capture
Lower weight of skull
Where does the frontal sinus drain?
Frontonasal duct to the semilunar hiatus on the lateral wall
Where does the ethmoid sinus drain?
3 of them:
anterior ethmoid sinus - semilunar hiatus
middle ethmoid sinus - ethmoid bulla
posterior ethmoid sinus - superior meatus
Where does the sphenoid sinus drain?
Into the roof of the nasal cavity
Where does the maxillary sinus drain?
Directly into the semilunar hiatus
What drains into the semilunar hiatus?
Maxillary, frontal and anterior ethmoid sinus
What drains into the ethmoid bulla?
Middle ethmoid sinus
What drains into the superior meatus?
Posterior ethmoid sinus
What is the pharynx?
Muscular tube connecting the oral and nasal cavities to the trachea and oesophagus
What are the 2 sets of pharyngeal muscles?
Circular and longitudinal muscles
What is the role of the circular pharyngeal muscles?
Food propulsion/peristalsis, contract sequentially - first superior constrictor, then middle constrictor, then inferior constrictor - to descend food
What is the role of the longitudinal pharyngeal muscles?
Change the shape of the pharynx and hold the larynx up to elevate it when swallowing closing off the pharyngeal inlet so that food and drink doesn’t travel in the wrong direction
What are the pharyngeal muscles innervated by?
The vagus apart from the stylopharyngeus which is innervated by the glossopharyngeal nerve CN IX.
Where is the larynx positioned?
Anterior neck at C3-C6 vertebrae
Begins where the airway and alimentary tracts separate
What is the function of the larynx?
Phonation and protection of the lower airway
What is the blood supply to the larynx?
Superior and inferior laryngeal arteries from ECA and thyrocervical trunk accordingly
What are the cartilages of the larynx?
3 unpaired - epiglottis, thyroid and cricoic
3 paired (6) - including arytenoids
Total 9
What does the thyroid look like?
Posteriorly looks like an open book
Is the adam’s apple anteriorly
Has superior and inferior horns
What does the epiglottis look like?
Leaf with stalk attached to thyroid anteriorly
What is the function of the epiglottis?
To flatten down during swallowing to close the laryngeal inlet
What is special about the cricoid?
Goes around the larynx completely - 360 degree angle
What is the function of the arytenoids?
Produce phonation by holding the vocal cords together to the thyroid and adjusting their distance from each other
What are the ligaments of the larynx? What do they do?
Cricothyroid need to be aware of as used for emergency airways
Hold muscles together
Others are thyrohyoid, cricotracheal
How do the arytenoids help produce sound/phonation?
Arytenoid cartilages move the vocal cords which then change the shape of the rima glottidis
What is the rima glottides?
Space of air which travels down to the lungs, controlled by movement of vocal folds which change its shape to produce sound
What are the vocal folds attached to?
Epiglottis and ligaments
What is the role of the intrinsic muscles of the pharynx?
Attach to the arytenoids to move the vocal cords to allow phonation
APART FROM CRICO|THYROID
What is the role of cricothyroid muscle?
Allows pitch by tilting the larynx, does not change the arytenoids in any way
What is the rima glottides like in different conditions?
Normal phonation - RG small and vocal cords tight
Normal respiration - RG wide
Exercising, deep inhalation - RG very wide
Whispering - RG very small
What are the function of the extrinsic larynx muscles?
Suprahyoid (above hyoid) and infrahyoid (below)
Sit outside larynx, protect airways and bring larynx up, attached to hyoid bone
What is the origin and pathway of the recurrent laryngeal nerve?
Originates from the vagus nerve, becomes recurrent laryngeal before larynx, which splits into R recurrent laryngeal which hooks under the subclavian artery and then goes back to the larynx and the L recurrent laryngeal which goes under the arch of aorta and then back to the larynx
What does the recurrent laryngeal supply?
All the intrinsic muscles apart from cricothyroid
sensory to area above vocal cords
What is the origin and pathway of the superior laryngeal?
From the vagus, gives off superior laryngeal below the larynx which splits into external (to cricothyroid) and internal (sensory to larynx)
What does the superior laryngeal nerve supply?
internal laryngeal - sensory to larynx above vocal cords
external laryngeal - motor to cricothyroid muscle (PITCH)
What happens if you get a lesion to the recurrent laryngeal?
vocal cord paralysis = hoarseness, aphonia, stridor (inspiratory barking noises)
What happens if you get a lesion to the superior laryngeal nerve?
Cricothyroid paralysis preventing higher pitched phonation = weak voice, low pitch, easily tires, reduced range
When is the recurrent laryngeal most likely damaged?
Surgery to the thyroid gland/neck trauma
What are the branches of the arch of aorta?
L to R:
brachiocephalic trunk - subclavian artery then R common carotid artery
L common carotid artery
L subclavian artery
Where does the R common carotid artery bifurcate and into what?
C4 - ICA and ECA
Where does the inferior laryngeal artery come from?
Thyrocervical trunk - R subclavian artery - brachiocephalic trunk
Where does the superior laryngeal artery come from?
Superior thyroid artery which is from ECA which is from superior laryngeal artery which is from R common carotid which is from brachiocephalic trunk
What is the surface anatomy of the larynx?
Adam’s apple is thyroid cartilage
next down is cricoid cartilage and bit in between these is cricothyroid ligament
What is endotracheal intubation?
Insertion of plastic tube via mouth past the vocal cords into the trachea producing a definitive controlled airway and allowing manipulation of ventilation and oxygenation
When may you have to do an endotracheal intubation?
Anaesthetised patients
critically unwell patients
impending airway obstruction
Why may an endotracheal intubation be difficult?
Can't get through vocal cords: limited neck mobility obese short mandible length facial trauma
How do you do an endotracheal intubation?
Palpate laryngeal prominence of thyroid cartilage
Work inferiorly to palpate cricoid cartilage to ascertain cricothyroid ligament
Make vertical incision from mid thyroid cartilage to superior aspect of cricoid cartilage
Puncture through cricothyroid membrane with horizontal scalpel
Insert airway. Easy!
