Structure of the Airway Flashcards
What is the definition of respiration?
Providing oxygen to the body and removing carbon dioxide through inhalation and exhalation
Ways you can increase the size of the thorax for inhalation?
Contraction of the diaphragm and raising the ribs
Creating a negative intra-thoracic pressure that sucks air through the conductive passages into the lungs
What are the components of the conductive passages?
Nasal cavity
nasopharynx
larynx
Bronchi
In what condition must air be in when it reaches the lungs?
Warmed, filtered and humidifed- achieved by vascular mucosa, cilia and mucus
How is exhalation achieved?
By decreasing the size of the thorax usually in a passive process (as no muscles are contracting so therefore no energy being expended)
What is the structure that marks entry to the nasal?cavity?
Nares
What holds the nasal cavities open?
Bone and cartilage
Where are the nasal cavities found?
Above the oral cavity, between the 2 orbits, posterior to the nose, and anterior to the nasopharynx
What lines the nasal cavities?
A highly vascularised mucosal membrane lined by respiratory epithelium
What composes the respiratory epithelium?
pseudostratified, ciliated, columnar, interspersed with goblet cells that secrete mucous
What is the nasal septum?
Mid-line cavity that separates right and left nasal cavities
What makes up the nasal septum?
Anteriorly it is made up of septal cartilage
Posteriorly it is made up of bone
What can happen if the septum is deviated from the midline?
Sinus drainage may be compromised and can predispose to sinusitis
What are the boundaries of the nasal cavities?
Nasal septum- medially
Soft and hard palates- floor
Nasal concae- laterally
Bone: frontonasal, ethmoid, sphenoid bone- roof
Where is the olfactory epithelium restricted to?
The roof and adjacent lateral wall of the nasal cavities
What are the 3 nasal conchae and what is its function?
Superior, middle and inferior
Provide turbulence and increase surface area for air flow and heat exchange, this helps humidify and moisten air as it enters the body
What is found under each concha and what is its function?
A meatus which works in communication between the sinuses and the nasal cavities
What structures makes up a nasal cavity?
Septum
Lateral walls with conchae
Meati
Airway
What do sinuses do?
Increase air space for breathing, moistening and humidifying air
What are sinuses?
Empty spaces in head, reduces the weight of the skull significantly
Where are orbits found?
Immediately lateral to nasal cavity
Where is the opening of the maxillary sinus found?
High in its medial wall
What is the clearance of mucous in the maxillary sinus dependent on?
ciliary action
What can happen if infection occurs in maxillary sinus?
Sinusitis- inflammation
Purpose of nasolacrimal duct in nasal cavity?
Drains tears from conjuctiva of eye
What is epistaxis?
Nosebleed
Why is the Keisselbach area common for epistaxis?
It is rich in anastomosing arteries
Consequences of lateral wall of nasal cavity being highly vascularised?
Helps warm air but is easily ruptured as the blood vessels are close to the surface
What does the vascular mucosa do?
anastomose between branches of external carotids and internal carotids
Where is the olfactory bulb and the nerves for smell located?
In the roof and upper parts of lateral wall of the nasal cavity
What is the pharynx?
A tube of fibrous and muscular tissue. It lies behind the nasopharynx, the oropharynx and the laryngopharynx
Properties of nasopharynx?
Transports air
Divided from oropharynx by soft palate
Found at the back of the nose
Properties of oropharynx?
Transports air, and food and fluid but must be separated so air is passed into larynx and food and fluid is continued to the laryngopharynx
Found at the back of the mouth
Purpose of epiglottis?
Can seal off trachea to stop food and fluid from entering the respiratory system
What is the larynx?
Membranous tube suspended between cartilages, its position is controlled by muscles
Why might laryngeal diameters be altered?
to allow the passage of air only
control airflow for speech
raising intra-abdominal pressure
What are the different types of laryngeal cartilages naming from the top to the bottom of the larynx?
Epiglottic
Thyroid
Arytenoid
Cricoid
What is the cricothyroid membrane used for?
Site of emergency access to airway
Purpose of quadrangular membrane?
Helps seal off airway to prevent food and fluid from entering the respiratory system
Where is the aryepiglottic fold located?
Upper edge of quadrangular membrane
Where is the vestibular fold located?
Lower edge of quadrangular membrane
Where is the vocal cord located?
Upper edge of cricovocal/cricothyroid membrane
What do aryepiglottic folds do?
Forms the larygneal inlet which is the protective sphincter
How is the laryngeal inlet closed and in what circumstances would it be closed?
Elevation of the larynx which is lifted up and forward during swallowing
What is the purpose of the surrounding muscles of the laryngeal inlet?
Aid closure and and widening of laryngeal inlet
Where is the saccule found?
Within the opening of the laryngeal ventricle
What is the saccule?
Structure containing mucosal glands which help lubricate the vocal cords
What is the purpose of the vocal cords?
Control laryngeal diameter for: speech coughing sneezing increasing intra-abdominal pressure micturition (peeing) defacation lifting heavy objects`
What is the rima glottidis?
Opening of laryngeal diameter
What are the main actions of laryngeal muscles?
close/open the inlet
close/open the rima glottidis
shorten/lengthen vocal cords
What is the muscle than opens the rima glottidis?
posterior crico-arytenoid
What does the superior laryngeal nerve do?
Supplies 1 muscle and sensation above vocal cords
What does the recurrent laryngeal nerve do?
Supplies all other muscles and sensation of the vocal cords and below
What surgeries put laryngeal nerves at risk?
Thyroid surgeries
Describe the location of the trachea?
In front of the oesophagus
Medial to carotid arteries and internal jugular veins
Inferior to larynx
Upper portion surrounded by thyroid gland
What can the trachea be divided into?
Left and right bronchi
Where does the larynx sit?
Above the trachea
