1 - Anatomy of the Respiratory System 1 Flashcards
What does the upper respiratory tract consist of and where does it develop from?
- Nostrils to lower border of the cricoid cartilage of the larynx.
- Nose, paranasal sinuses, pharynx and larynx.
- Comes from primitive gut tube so endoderm and explains why might get fistulas
What is the structure of the nasal cavity and what are it’s functions?
- Median nasal septum separates two sides and 3 bony projections called conchae on lateral walls
- Cold air irritates airway and dry air difficult for gas exchange. Adds water in and takes it out.
- Turbulent flow slows and gives time for warming and humidifying
- Hairs in nose trap large particles and waft to oropharynx to be swallowed
To summarise
Median nasal septum
Nasal Conchae (To slow down, turbulent air)
Hair to trap particles
What are the paranasal sinuses?
- Lined by pseudostratified and they open into the turbinates in the nasal cavity. Usually full of air.
- Keeps head light along with thin compressed bones
Turbinates are small structures inside the nose that cleanse and humidify air that passes through the nostrils into the lungs.
What is the structure and function of the pharynx?
And what happens if these mechanisms fail?
Pharynx coordinates swallowing and breathing, if mechanisms fail aspiration pneumonia can occur
Aspiration pneumonia occurs when food or liquid is breathed into the airways or lungs, instead of being swallowed.
What is the structure and function of the larynx?
- Links pharynx to the trachea and contains vocal cords that guard the entrance to the trachea
What is the role of the vocal cords (a.k.a vocal folds or ligaments)?
- Form a glottis with the aperture between the cords
- When swallowing laryngeal inlet narrows, epiglottis folds down over inlet, vocal cords come together and act as a sphincter to close trachea
- Movement of cords due to intrinsic laryngeal muscles supplied by recurrent laryngeal nerve. This nerve on the left goes down to thoracic cavity so hoarse voice can signal intra-thoracic disease
What can the vocal cords be linked to clinically?
- Aspiration: if folds dysfunctional there is a choking hazard
- Cough reflex: Closing cords allows intra-thoracic pressure to build up to allow inhaled particles and excessive airway secretions to be removed
- Airway obstruction: opening between vocal cords can get blocked and cause choking
- Intra Thoracic Disease: voice change due to paralysis of left recurrent laryngeal nerve
Aspiration is when something enters the airway or lungs by accident
What does the conducting airways consist of?
How would you go about removing a lung tumour?
Look at pulmonary segment map and only remove this segment to minimise bleeding
What does the bony thorax consist of?
Sternum, ribs, thoracic vertebrae, costovertebral joints and rib movements
Explain the anatomy of a rib.
- Typical rib 3-9 has head, neck, tubercle, shaft
- Head has 2 articular facets with vertebrae
- Tubercle has one facet for transverse process
- Flat curved shaft has costal groove near lower border for vessels
- Costovertebral joints are what move during breathing
What are the main muscles responsible for breathing?
- External intercostal: anteroinferior. bucket handle. 30% of chest expansion during quiet breathing
- Internal intercostal: right angle to external. Pull ribs down and used during forced expiration
- Innermost intercostal: act with internal but less developed
- Diaphragm: 70% chest expansion in quiet breathing
EIID LOL
What are the different movements of the thoracic cavity during respiration?
What is the anatomy and role of the diaphragm?
- Innervated by R and L phrenic nerves (C3,C4,C5)
- Right dome: 5th rib
- Left dome: 5th ICS
- Inferiorly: attaches to lower margin of thoracic cavity
- Superiorly: attaches to central tendon fused with inferior pericardium
Where are the openings in the diaphragm and what passes through them?
- Vena Cava: T8 level
- Oesophagus: T10 level
- Aortic Hiatus: T12
COUNT THE LETTERS
Where would you insert a chest drain and why?
Above a rib not below as the main neurovasculature just below ribs so risk of bleeding and paralysis
What is the possible diagnosis of this chest x-ray?
Phrenic nerve palsy leading to elevated hemi-diaphragm on affected side
What are some of the accessory breathing muscles?
- SCM: elevates sternum
- PM: pulls ribs out
- RA: compress abdomen
- QL: pull ribs down
Why do we need to think about penetrating upper chest injuries on a deeper level?
Due to dome of the diaphragm the thoracic cavity is smalle than the bony thorax suggests so liver, spleen, stomach and kidneys lie up near the ribs so could be injured
What is the arterial supply to the lungs?
- Dual
- Bronchial: supply bronchial tree, not alveoli, and the visceral pleura
- Pulmonary: alveoli and lungs for gas exchange
Some anastomoses between the two which can help maintain blood supply in PE
What is the venous drainage of the lungs?
- Pulmonary: return oxygenated blood to left heart. Don’t follow bronchi, tend to run in intersegmental septa. Two pulmonary veins in hilum, one draining each lobe
- Bronchial veins –> Azygous Vein –> SVC
What is the lymphatic drainage of the lungs?
- Hilar nodes (a.k.a bronchopulmonary nodes)
- Hilar drain to tracheobronchial nodes
- Enlargement of tracheobronchial nodes can widen angle of carina
What is the nerve supply to the lungs?
- Right and left vagus nerves and the sympathetic trunk
- Parasympathetic efferent fibres from vagus are motor to bronchial smooth muscle and secretomotor to mucous glands. Afferent for cough reflex and pain
- Sympathetic efferent bronchodilator and vasoconstrictor
What is the blood and nerve supply to the intercostal muscles?
- Ventral rami of thoracic spinal nerves
- Intercostal arteries
