1. Anatomy of the Respiratory System Flashcards
What does the upper respiratory tract comprise of?
The URT extends from the nostrils to to the lower border of the cricoid cartilage of the larynx and comprises of the Nose & paranasal sinuses, Pharynx and Larynx.
What divides the nasal cavity into right & left cavities ?
median nasal septum
What is found on the lateral wall of each nasal cavity and what are they called?
3 bony projections known as the conchae or turbinates
What are the paranasal sinuses? Name them.
Air containing cavities that lightens weight of the head and named for the skull bones within which they are situated: frontal, maxillary, spheroidal and ethmoidal.
What are paranasal sinuses lined by and what do they open into?
They are lined by respiratory epithelium (pseudo
stratified ciliated columnar epithelium) and open into the spaces below the turbinates in the nasal cavity
Which structures provide large SA in the nasal cavity and why is this important?
Tubinates and paranasal sinuses, allow inhaled air to be warmed and humidified.
What does the nasal cavity do to air flow, what causes this and why is this important?
Turbinates cause turbulence and slows air flow increasing time available for warming and humidification.
What structure is responsible for warming and humidification of the air through the nasal cavity?
The vascular mucosa epithelium lining the nasal cavity.
How is air humidified through the nasal cavity?
By transudation of fluid through the epithelium and to a lesser extent by mucus secretion.
What is the glottis?
The vocal cords + the aperture(opening) between the cords, are together termed the `glottis’
How does the nostrils trap particles?
Each nostril is lined with coarse hairs which trap large particles in inhaled air. The mucus secreted by the goblet cells traps almost all particles >5 micrometers. The cilia waft the mucus to oropharynx where it is swallowed.
What mechanism ensures food does not enter the larynx?
During swallowing, the laryngeal inlet becomes narrowed, the epiglottis folds downwards (like a lid) over the laryngeal inlet and the vocal cords come together (are adducted) to act as a sphincter closing off the entrance to the trachea
Why does the body need a mechanism to ensure food does not enter the larynx?
Air & food have a common passage through parts of the pharynx. Hence, mechanisms to prevent aspiration
(inhalation) of food particles during swallowing are important
What are the consequences of Failure of these mechanisms ?
aspiration of food particles /liquid leading to
potentially life-threatening airway obstruction and/or infection (aspiration pneumonia).
Which muscles control movements of the vocal cords and which nerve is responsible?
Caused by the action of the intrinsic laryngeal muscles. The recurrent laryngeal nerve supplies all intrinsic muscle (except the cricothyroid muscle)`How might intrathoracic disease cause a hoarse voice?
How might intrathoracic disease cause a hoarse voice?
Left recurrent laryngeal nerve passes inside the thoracic cavity. Hence intra thoracic disease (e.g. aortic aneurysm, lung cancer) compressing or infiltrating the nerve can result in a hoarse voice, due to paralysis of the left vocal cord
What is and causes aspiration?
If the larynx and vocal folds are dysfunctional, the trachea may not be properly closed off during swallowing, hence there is a risk of inhalation (aspiration) of food/liquid.
How does the cough reflex occur and why is it important?
Vocal cords close to build intrathoracic pressure and suddenly open so air is expelled at high velocity. protective to expel inhaled particles s, and also
serves as a clearance mechanism for disposing of
excessive secretions from the airways.
What can Voice change be the first sign of?
serious intra-thoracic disease, due to involvement of the left recurrent laryngeal nerve in the thorax
What does the Bony Thorax consist of?
sternum, ribs, thoracic vertebrae, costovertebral joints and rib movements
What does the sternum consist of?
consists of the manubrium, body and the xiphisternum (which remains cartilaginous into adult life).
What is the junction of the manubrium & sternal body is known as?
sternal angle and is felt as a transverse ridge on palpation of the sternum.
Where does the 2nd costal cartilage articulate with the sternum?
at the level of the sternal angle. (angle of Louis)
This enables the 2nd rib to be identified, and the rest of ribs can be counted downwards from here
Which parts of the thoracic cavity for the “respiratory pump” and which part forms the surface for gas exchange?
The Bony thorax, intercostal muscles and the diaphragm function together as a “respiratory pump” to ventilate the lungs, while the organization of airways and blood vessels provides the interface for gas exchange.
Describe the structure of ribs
A` typical’ rib (ribs 3-9) has a head, a neck, a
tubercle, and a shaft
What are the functions of the nasal cavity?
- induce turbulent flow (nasal conchae)
- warm and moisten inspired air
- recover water from expired air
- speech production(phonation)
- olfaction
Why do we want to warm and moisten inspired air
- cold air irritates the nasal cavity
- moisten to dissolve gases for better diffusion - gases don’t diffuse across dry membranes very well
Which plane is the floor of the nasal cavity?
horizontal floor
why does the later walls of the nasal cavity have a large surface area?
to increase area for warming and water retention
describe the location of the trachea and oesophagus
trachea anteriorly
oesophagus posteriorly
What is the larynx and what is its function
The larynx, commonly called the voice box, is an organ in the top of the neck involved in breathing, producing sound and protecting the trachea against food aspiration. The larynx houses the vocal folds, and manipulates pitch and volume, which is essential for phonation
What is the epiglottis?
The epiglottis is a leaf-shaped flap in the throat that prevents food from entering the windpipe and the lungs. It stands open during breathing, allowing air into the larynx.
What is the pharynx?
The pharynx is the part of the throat behind the mouth and nasal cavity, and above the esophagus and larynx – the tubes going down to the stomach and the lungs.
Describe the articular facets of ribs
The head: has 2 articular facets that articulate with the
body of the corresponding vertebra and the vertebra
above, forming the costovertebral joints
The tubercle: has one articular facet for articulation with the transverse process of the corresponding thoracic vertebra (forming the costotransverse joints and present in all vertebrae except T11 and T12)
Describe the shaft of the ribs
the flat, curved shaft has a groove (the costal
groove) on its inner aspect, near the lower border in which the intercostal vessels & nerve run.
What are the muscles of the intercostal space and what are they innervated by?
external, internal and innermost intercostal muscles, innervated by the intercostal nerves
At which joint does the movement of ribs occur at during respiration?
Costovertebral joints
What are the orientation of the fibres of the external intercostal muscles, how much does it contribute to chest expansion in quiet breathing and what type of chest movement does it cause?
Run anterio-inferiorly. Contributes 30%.
Elevates ribs in bucket handle movement: increases AP and transverse diameters of the chest.
What are the orientation of internal intercostal muscles and what is their function?
Run posterioinferiorly. Pulls the ribs down from position of expansion only in forced expiration.
What are the orientation of innermost intercostal muscles and what is their function?
Run posterioinferiorly. Pulls the ribs down from position of expansion only in forced expiration. (Same as internal incostal muscles)
Where are the neurovascular structures of the intercostal muscles found?
Between the inner 2 layers
What are the main arterial supplies to the intercostal muscles and where do they originate from?
Posterior intercostal arteries (aorta) and anterior intercostal arteries (internal thoracic artery, from subclavian)
Where does the posterior thoracic artery run and what are its branches?
Run just below the rib. Gives collateral branch that runs just above the rib below. Gives a lateral branch.
Where does the anterior thoracic artery run and what are its branches?
Have 2 branches that run just below rib and just above the rib below. Also gives anterior perforating branch.
What are the main venous supplies to the intercostal muscles and where do they drain into?
Anterior intercostal veins (internal thoracic vein), posterior intercostal veins (Azygous venous system)
